@article {2475, title = {High Temperature End of the So-Called "Koga Line": Anomalies in Temperature Derivatives of Heat Capacities}, journal = {Journal of Physical Chemistry B}, volume = {113}, number = {17}, year = {2009}, note = {ISI Document Delivery No.: 438BCTimes Cited: 0Cited Reference Count: 24Koga, Yoshikata Westh, Peter Moriya, Yosuke Kawasaki, Koji Atake, Tooru}, month = {Apr}, pages = {5885-5890}, type = {Article}, abstract = {The so-called "Koga line" is a collection of the loci of anomalies in various third derivatives of the Gibbs function, G, in the temperature-mole fraction field for aqueous solutions of nonelectrolytes. This splits the H2O-rich region into two, in each of which the molecular organization and interactions-we call it mixing scheme-is qualitatively different. In this work, we attempt to locate the high temperature end of the Koga line. This is a particularly interesting range of the boundary, since its extrapolation to zero Solute concentration provides information on possible temperature induced changes in the properties of pure water. To this end, we determine semi-isobaric heat capacities of aqueous 2-butoxyethanol by adiabatic calorimetry up to a maximum of 95 degrees C. The corrections due to vaporization were not applied due to the lack of required vapor pressure and thermal expansivity data. Furthermore, we measured directly the isobaric heat capacities per molar volume for aqueous I-propanol as well as 2-butoxyethanol by differential scanning calorimetry up to 120 degrees C at 3 atm. We then took one more temperature derivative of the respective heat capacity data. The resulting third derivative quantities from the former data showed step-type anomalies, while those from the latter negative peak-type anomalies. The loci of these anomalous points seem to point to about 70 degrees C at infinite dilution.}, keywords = {25-DEGREES-C, AQUEOUS 2-BUTOXYETHANOL, density, FLUCTUATION, METHANOL, MIXING SCHEME, PARTIAL MOLAR VOLUMES, pressure, TRANSITION, WATER-RICH REGION}, isbn = {1520-6106}, url = {://000265529900029}, author = {Koga,Yoshikata and Westh, P. and Moriya, Y. and Kawasaki, K. and Atake, T.} } @article {2553, title = {Pseudospectral method of solution of the Fitzhugh-Nagumo equation}, journal = {Mathematics and Computers in Simulation}, volume = {79}, number = {7}, year = {2009}, note = {ISI Document Delivery No.: 429KBTimes Cited: 3Cited Reference Count: 41Olmos, Daniel Shizgal, Bernie D.}, month = {Mar}, pages = {2258-2278}, type = {Article}, abstract = {We present a study of the convergence of different numerical schemes in the solution of the Fitzhugh-Nagumo equations in the form of two coupled reaction diffusion equations for activator and inhibitor variables. The diffusion coefficient for the inhibitor is taken to be zero. The Fitzhugh-Nagumo equations, have spatial and temporal dynamics in two different scales and the solutions exhibit shock-like waves. The numerical schemes employed are a Chebyshev multidomain method, a finite difference method and the method developed by Barkley [D. Barkley, A model for fast computer simulation of excitable media, Physica D, 49 (1991) 61-70]. We consider two different models for the local dynamics. We present results for plane wave propagation in one dimension and spiral waves for two dimensions. We use an operator splitting method with the Chebyshev multidomain approach in order to reduce the computational time. Zero flux boundary conditions are imposed on the solutions. (C) 2009 IMACS. Published by Elsevier B.V. All rights reserved.}, keywords = {3-DIMENSIONAL EXCITABLE MEDIA, Chebyshev multidomain, Convergence, DYNAMICS, Fitzhugh-Nagumo equations, MECHANISM, MODEL, REACTION-DIFFUSION-SYSTEMS, SELECTION, Spiral waves, SPIRAL-WAVE, TRANSITION}, isbn = {0378-4754}, url = {://000264918200021}, author = {Olmos, D. and Shizgal, B. D.} } @article {1365, title = {Low-N lines of the A(6)Sigma(+)-X-6 Sigma(+) (1,0) band of CrH}, journal = {Physical Chemistry Chemical Physics}, volume = {8}, number = {7}, year = {2006}, note = {ISI Document Delivery No.: 019BRTimes Cited: 3Cited Reference Count: 20}, month = {Feb}, pages = {822-826}, type = {Article}, abstract = {{The (1,0) band of the A(6)Sigma(+) - X-6 Sigma(+) electronic transition of CrH has been observed by laser-induced fluorescence following the reaction of laser-ablated Cr atoms with methanol under supersonic free-jet cooled conditions. Rotational assignments of the levels with N <= 3 have been made by combination differences and dispersed fluorescence experiments on selected lines. These assignments complement those made from previously-recorded Fourier transform emission spectra, in which higher-N lines were assigned. The low-N rotational levels are extensively perturbed, presumably by levels of the a(4)Sigma(+)}, keywords = {LASER MAGNETIC-RESONANCE, SPECTRUM, STATE, SYSTEM, TRANSFORM EMISSION-SPECTROSCOPY, TRANSITION}, isbn = {1463-9076}, url = {://000235811100004}, author = {Chowdhury, P. K. and Merer, A. J. and Rixon, S. J. and Bernath, P. F. and Ram, R. S.} } @article {1374, title = {Monte Carlo simulations of the adsorption of CO2 on the MgO(100) surface}, journal = {Journal of Chemical Physics}, volume = {124}, number = {11}, year = {2006}, note = {ISI Document Delivery No.: 023XRTimes Cited: 10Cited Reference Count: 30}, month = {Mar}, pages = {9}, type = {Article}, abstract = {The adsorption of CO2 gas on the MgO (100) crystal surface is investigated using grand canonical Monte Carlo simulations. This allows us to obtain adsorption isotherms that can be compared with experiment, as well as to explore the possible formation of monolayers of different densities. Our model calculations agree reasonably well with the available experimental results. We find a {\textquoteright}{\textquoteright} low-density {\textquoteright}{\textquoteright} adsorbed monolayer where each CO2 molecule is bound to two Mg2+ ions on the MgO substrate. We also observe the formation of monolayers of higher density, where some of the CO2 molecules have rotated and tilted to expose additional binding sites. Low-temperature simulations of both the low- and high-density monolayers reveal that these states are very close in energy, with binding energies of approximately 7 kcal/mol at T=5 K. The high-density monolayer given by our model has a density that is significantly less than the reported experimental value. We discuss this discrepancy and offer suggestions for resolving it. (c) 2006 American Institute of Physics.}, keywords = {CARBON-DIOXIDE, DYNAMICS, LEED, MODEL, MONOLAYERS, SINGLE-CRYSTAL SURFACE, TRANSITION}, isbn = {0021-9606}, url = {://000236160000043}, author = {Daub, C. D. and Patey, G. N. and Jack, D. B. and Sallabi, A. K.} } @article {1316, title = {The 4051-angstrom band of C-3 ((A)over-tilde(1)Pi(u)-(X)over-tilde(1)Sigma(+)(g), 000-000): Perturbed low-J lines and lifetime measurements}, journal = {Journal of Chemical Physics}, volume = {122}, number = {24}, year = {2005}, note = {ISI Document Delivery No.: 943DNTimes Cited: 5Cited Reference Count: 31}, month = {Jun}, pages = {8}, type = {Article}, abstract = {Rotational analyses have been carried out at high resolution for the 000-000 and 000-100 bands of the A (1)Pi(u)-X (1)Sigma(g)(+) transition of supersonic jet-cooled C-3. Two different spectra have been recorded for each band, using time gatings of 20-150 and 800-2300 ns. At the shorter time delay the spectra show only the lines observed by many previous workers. At the longer time delay many extra lines appear, some of which have been observed previously by [McCall Chem. Phys. Lett. 374, 583 (2003)] in cavity ring-down spectra of jet-cooled C-3. Detailed analysis of these extra lines shows that at least two long-lived states perturb the A (1)Pi(u), 000 state. One of these appears to be a (3)Sigma(u)(-) vibronic state, which may possibly be a high vibrational level of the b (3)Pi(g) state, and the other appears to be a P=1 state with a low rotational constant B. Our spectra also confirm the reassignment by McCall of the R(0) line of the 000-000 band, which is consistent with the spectra recorded towards a number of stars that indicate the presence of C-3 in the interstellar medium. Fluorescence lifetimes have been measured for a number of upper-state rotational levels. The rotational levels of the A (1)Pi(u) state have lifetimes in the range of 230-190 ns, decreasing slightly with J; the levels of the perturbing states have much longer lifetimes, with some of them showing biexponential decays. An improved value has been obtained for the nu(1) vibrational frequency of the ground state, nu(1)=1224.4933 +/- 0.0029 cm(-1). (c) 2005 American Institute of Physics.}, keywords = {C3, CHAIN, EMISSION-SPECTRA, INTERSTELLAR C-3, MOLECULE, SPECTROSCOPY, STATES, TRANSITION, TRANSLUCENT SIGHT LINES}, isbn = {0021-9606}, url = {://000230332400023}, author = {Zhang, G. Q. and Chen, K. S. and Merer, A. J. and Hsu, Y. C. and Chen, W. J. and Shaji, S. and Liao, Y. A.} } @article {1224, title = {Solvent phase behavior and the interaction of uniform and patterned solutes}, journal = {Journal of Chemical Physics}, volume = {123}, number = {19}, year = {2005}, note = {ISI Document Delivery No.: 985CHTimes Cited: 2Cited Reference Count: 42}, month = {Nov}, pages = {10}, type = {Article}, abstract = {Isotropic and anisotropic hypernetted-chain (HNC) integral equation theories are used to obtain the interaction of solutes both near and far from the solvent liquid-vapor coexistence. Spherically symmetrical and chemically patterned (patched) solutes are considered, and the influences of particle and patch sizes are investigated. Solvophilic and solvophobic solutes (or patches) are examined. Near coexistence, in the solvophobic case drying like behavior occurs for solutes (patches) of sufficient size. This gives rise to relatively long ranged attractive forces that are strongly orientation dependent for the patched solute particles. We also report grand canonical Monte Carlo results for a pair of spherically symmetric solutes. This demonstrates that the anisotropic HNC theory gives qualitatively correct solvent structure in the vicinity of the solutes. Comparison with previous simulations also shows that the solute-solute potentials of mean force given by the anisotropic theory are more accurate (particularly at small separations) than those obtained using the isotropic method. (c) 2005 American Institute of Physics.}, keywords = {BINARY-FLUID MIXTURE, BRIDGE DIAGRAM SERIES, HYDROPHOBIC SURFACES, INTEGRAL-EQUATION, LENNARD-JONES FLUIDS, MACROPARTICLES, MEAN FORCE, RANGE, SPHERICALLY INHOMOGENEOUS FLUIDS, TRANSITION}, isbn = {0021-9606}, url = {://000233353200029}, author = {Overduin, S. D. and Patey, G. N.} } @article {984, title = {Coulomb collisional processes in space plasmas; relaxation of suprathermal particle distributions}, journal = {Planetary and Space Science}, volume = {52}, number = {10}, year = {2004}, note = {ISI Document Delivery No.: 858UKTimes Cited: 4Cited Reference Count: 38}, month = {Aug}, pages = {923-933}, type = {Article}, abstract = {Nonequilibrium distributions of space plasmas are often characterized by extended high-energy tails. This paper provides a detailed analysis of the relaxation of such isotropic nonequilibrium plasmas. We consider an energetic charged species dilutely dispersed in a fully ionized plasma, which acts as a heat bath at equilibrium. The minor constituent is referred to as a "test particle" and collisions between test particles are not included. We study the approach to equilibrium with a finite difference method of solution of the Fokker-Planck equation appropriate for collisions between charged particles. The solution of the Fokker-Planck equation is also presented formally as an expansion in the eigenfunctions of the Fokker-Planck operator. The main objective of the paper is the calculation of the energy-dependent relaxation times of the distribution function. A strong energy dependence for these relaxation times is anticipated since, for Coulomb collisions, the Rutherford cross-section varies with relative speed g as g(-4). Analogous results for neutral species are presented for comparison in the following paper. (C) 2004 Elsevier Ltd. All rights reserved.}, keywords = {ELECTRON VELOCITY DISTRIBUTION, equations, GAS, H+, KINETIC-MODEL, NUMERICAL-METHODS, POLAR WIND, relaxation, SOLAR-WIND, TEMPERATURE, TRANSITION}, isbn = {0032-0633}, url = {://000224217300004}, author = {Shizgal, B. D.} } @article {656, title = {Excess partial molar entropy of alkane-mono-ols in aqueous solutions at 25 degrees C}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {81}, number = {2}, year = {2003}, note = {ISI Document Delivery No.: 652JVTimes Cited: 9Cited Reference Count: 21}, month = {Feb}, pages = {150-155}, type = {Article}, abstract = {In the preceding paper, we reported the values of model-free chemical potentials for aqueous methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 1-hexanol at 25degreesC over the entire compositional region. Using alcohol excess partial molar enthalpies, H-AL(E), determined earlier in this laboratory (Can. J. Chem. 74, 713 (1996)), we have calculated excess partial molar entropies for the alcohols, S-AL(E), where AL stands for an alcohol. We then calculated, numerically, the entropic interaction, S-AL-AL(E) = N(partial derivativeS(AL)(E)/partial derivativen(AL))(p,T,nW), where n(AL) is the amount of AL, n(W) is the amount of H2O, and N is the total amount of solution. S-AL-AL(E) signifies the effect of addition of AL upon the entropic situation of existing AL in solution. Using these quantities, the mixing schemes in aqueous alcohols have been studied. The earlier conclusions, which used H-AL(E) and H-AL-AL(E) alone, are confirmed. Furthermore, the order of the relative hydrophobic nature of alcohols is established from the behaviour of S-AL-AL(E) and of H-AL-AL(E) as methanol < ethanol < 2-propanol < 1-propanol.}, keywords = {2-BUTOXYETHANOL, ALCOHOL, aqueous alcohols, BUTANOL, ENTHALPIES, entropic interaction, excess partial molar entropies, hydrophobicity ranking, MIXING SCHEME, MIXING SCHEMES, MIXTURES, NONELECTROLYTES, TRANSITION, VOLUMES, WATER-RICH REGION}, isbn = {0008-4042}, url = {://000181376800004}, author = {Koga,Yoshikata and Westh, P. and Nishikawa, K.} } @article {479, title = {Fourier transform emission spectroscopy of a new (2)Phi-1(2) Delta system of VO}, journal = {Journal of Molecular Spectroscopy}, volume = {211}, number = {2}, year = {2002}, note = {ISI Document Delivery No.: 547WFTimes Cited: 11Cited Reference Count: 39}, month = {Feb}, pages = {279-283}, type = {Article}, abstract = {High-resolution emission spectra of VO have been recorded in the region 3400-19400 cm(-1) using a Fourier transform spectrometer. The molecules were observed from the reaction of VOCl3 with active nitrogen. Two new bands, with origins near 5539.46 and 5551.69 cm(-1), are assigned as the 0-0 bands of the (2)Phi(5/2)-(2)Delta(3/2) and (2)Phi(7/2)-(2)Delta(5/2) spin-orbit components (respectively) of a (2)Phi-1(2)Delta electronic transition of VO. A rotational analysis of both subbands has been carried out and spectroscopic constants have been extracted. The 1(2)Delta state is known from the previous analysis of the near infrared doublet transitions of VO and the new (2)Phi excited state has rotational constants very similar to those of another (2)Phi state observed previously [Merer et al., J. Mol. Spectrosc. 125, 465 (1987)]. (C) 2002 Elsevier Science (USA).}, keywords = {BAND, OXIDES, PERTURBATIONS, ROTATIONAL STRUCTURE, SPECTRA, STATES, TRANSITION}, isbn = {0022-2852}, url = {://000175355100014}, author = {Ram, R. S. and Bernath, P. F. and Davis, S. P. and Merer, A. J.} } @article {531, title = {Numerical study of a direct current plasma sheath based on kinetic theory}, journal = {Physics of Plasmas}, volume = {9}, number = {2}, year = {2002}, note = {ISI Document Delivery No.: 514CHTimes Cited: 8Cited Reference Count: 43}, month = {Feb}, pages = {691-700}, type = {Article}, abstract = {A fully kinetic theory model was developed to study plasma properties of the sheath of a direct current glow discharge. This model includes a direct numerical solution of the Boltzmann equations for electron and ion distribution functions with a self-consistent electric field obtained from the Poisson equation. The calculated profiles of density, drift velocity, temperature, and electric potential were used to show the structure of the plasma sheath. The results of the direct numerical solution were compared with a particle-in-cell Monte Carlo simulation. It was also demonstrated that for a small Debye length to the ion mean-free path ratio, results obtained using the continuum sheath model, which includes two parameters, can be matched to the kinetic theory simulations. (C) 2002 American Institute of Physics.}, keywords = {BOHM CRITERION, CATHODE FALL, COLLISIONAL, ELECTRON MOTION, HELIUM, IONS, MODEL, MONTE-CARLO SIMULATION, RF GLOW-DISCHARGES, SHEATH, TRANSITION}, isbn = {1070-664X}, url = {://000173418700039}, author = {Vasenkov, A. V. and Shizgal, B. D.} } @article {530, title = {Self-consistent kinetic theory of a plasma sheath}, journal = {Physical Review E}, volume = {65}, number = {4}, year = {2002}, note = {ISI Document Delivery No.: 544FBTimes Cited: 8Cited Reference Count: 35Part 2B}, month = {Apr}, pages = {9}, type = {Article}, abstract = {A fully kinetic theory model of the sheath of a dc glow discharge is presented. This model includes a direct numerical solution of Boltzmann equations for the spatial and velocity dependence of the electron and Ar+ distribution functions with a self-consistent electric field calculated from the Poisson equation. The solution is obtained using a collocation method that employs Legendre quadrature points for both angular and spatial variables, and nonclassical speed quadrature points for velocity. The results of the steady state direct numerical solution are compared with a particle-in-cell Monte Carlo simulation. As anticipated, it is found that the space- and energy-dependent ion distribution function varies strongly with a decrease in the ratio of the Debye length to the ion mean free path.}, keywords = {COEFFICIENTS, COLLISIONLESS PLASMA, IONS, MODEL, MONTE-CARLO SIMULATION, MOTION, NEUTRALS, PRESHEATH, TRANSITION}, isbn = {1063-651X}, url = {://000175146600014}, author = {Vasenkov, A. V. and Shizgal, B. D.} } @article {5050, title = {Fourier transform microwave spectroscopy of the (2)Sigma(+) ground states of YbX (X=F, Cl, Br): Characterization of hyperfine effects and determination of the molecular geometries}, journal = {Journal of Chemical Physics}, volume = {115}, number = {15}, year = {2001}, note = {ISI Document Delivery No.: 478ZYTimes Cited: 17Cited Reference Count: 34}, month = {Oct}, pages = {6979-6989}, type = {Article}, abstract = {The pure rotational spectra of low lying v=0 and 1 vibrational levels of the (2)Sigma (+) ground states of several isotopomers of YbF, YbCl, and YbBr were recorded using a pulsed jet cavity Fourier transform microwave spectrometer. Through least squares fits, parameters describing rotational, fine, and hyperfine effects (such as Fermi-contact, dipole-dipole coupling, and nuclear spin-rotation coupling) are presented. Trends in this halide series show an increasing amount of unpaired spin-density on the halide nucleus with increasing halide atomic number, which is consistent with results obtained in previous studies of the calcium analogs. Effective equilibrium bond lengths for (YbF)-Yb-174 and (YbCl)-Yb-174-Cl-35 have been determined to be 2.016 514(1) Angstrom and 2.488 285(1) Angstrom, respectively. The spectra of the two major bromine isotopomers, (YbBr)-Yb-174-Br-79 and (YbBr)-Yb-174-Br-81, were studied only in the v=0 level, and the derived values of r(0) are 2.647 364 5(2) Angstrom and 2.647 347 6(2) Angstrom, respectively. The uncertainties in the equilibrium bond lengths of YbF and YbCl are discussed in terms of the measurement accuracies of the spectra and of the Born-Oppenheimer approximation. (C) 2001 American Institute of Physics.}, keywords = {BEAM, CONSTANTS, laser spectroscopy, MONOBROMIDE, MONOFLUORIDE, PURE ROTATIONAL SPECTRUM, RF DOUBLE-RESONANCE, SPIN-ROTATION, TRANSITION, X(2)SIGMA(+) STATE}, isbn = {0021-9606}, url = {://000171380500024}, author = {Dickinson, C. S. and Coxon, J. A. and Walker, N. R. and Gerry, M. C. L.} } @article {4935, title = {The electronic spectrum of silicon methylidyne (SiCH), a molecule with a silicon-carbon triple bond in the excited state}, journal = {Journal of Chemical Physics}, volume = {112}, number = {8}, year = {2000}, note = {ISI Document Delivery No.: 284RDTimes Cited: 22Cited Reference Count: 56}, month = {Feb}, pages = {3662-3670}, type = {Article}, abstract = {The (A) over tilde (2)Sigma(+)-X (2)Pi(i) transition of jet-cooled silicon methylidyne, SiCH, has been recorded by laser-induced fluorescence in the 850-600 nm region. The radical was produced in an electric discharge using tetramethylsilane as the precursor. Fifteen cold bands of SiCH and 16 bands of SiCD have been assigned vibrationally, giving the upper state frequencies as v(2)({\textquoteright})=715/558 cm(-1) and v(3)({\textquoteright})=1168/1127 cm(-1) for SiCH/SiCD. Rotational analysis of the 0(0)(0) and 3(0)(3) bands for each isotopomer has given the following molecular structures: r(0)({\textquoteright})(Si-C)=1.692 52(8), r(0)({\textquoteright})(C-H)=1.0677(4), r(0)({\textquoteright})(Si-C)=1.6118(1), and r(0)({\textquoteright})(C-H)=1.0625(5) Angstrom. The silicon-carbon bond length in the X (2)Pi ground state of SiCH (electron configuration ...sigma(2)pi(3)) is typical for a Si=C double bond; in the (A) over tilde (2)Sigma(+) excited state (...sigma(1)pi(4)) it corresponds to a triple bond. This work provides the first experimental measurement of the length of the carbon-silicon triple bond. (C) 2000 American Institute of Physics. [S0021-9606(00)00508-0].}, keywords = {DISCHARGE JET SPECTROSCOPY, FREQUENCIES, GAS-PHASE, GEOMETRY, laser spectroscopy, MONOFLUOROSILYLENE, ROTATIONAL ANALYSIS, SIMPLEST UNSATURATED SILYLENE, SYSTEM, TRANSITION, vibrational}, isbn = {0021-9606}, url = {://000085345300022}, author = {Smith, T. C. and Li, H. Y. and Clouthier, D. J. and Kingston, C. T. and Merer, A. J.} } @article {4958, title = {Interactions in D-fructose-1-propanol-H2O: the effect of D-fructose on the molecular organization of liquid H2O}, journal = {Fluid Phase Equilibria}, volume = {171}, number = {1-2}, year = {2000}, note = {ISI Document Delivery No.: 349EQTimes Cited: 5Cited Reference Count: 27}, month = {May}, pages = {151-164}, type = {Article}, abstract = {Densities of binary aqueous solutions of D-fructose (abbreviated as FR hereinafter) were determined in a much wider mole fraction range than available in literature. In contrast to hydrophobic solutes, the partial molar volume of FR, V-FR, does not show an initial decrease on increasing the mole fraction of FR, x(FR). In order to learn more about the effect of FR on the molecular organization of liquid H2O, the excess chemical potentials and partial molar enthalpy of 1-propanol (1P) were determined in ternary 1P-FR-H2O system. Namely, the detailed thermodynamic behaviour of 1P in the ternary system was used as a probe to elucidate the effect of FR on liquid H2O. In comparison with earlier results of the temperature dependence of tert-butanol (TBA)-TBA interaction functions, addition of FR seems to have a similar effect of temperature increase on the molecular organization of H2O. We suggest that addition of FR tends to decrease the global average of hydrogen bond probability of H2O. (C) 2000 Elsevier Science B.V. All rights reserved.}, keywords = {25-DEGREES-C, AQUEOUS-SOLUTIONS, BUTYL ALCOHOL-SOLUTIONS, chemical potential, CHEMICAL-POTENTIALS, D-fructose-1-propanol-H2O, effect of beta-D-fructose on H2O, INTERMOLECULAR INTERACTIONS, MIXING SCHEME, PARTIAL MOLAR ENTHALPIES, partial molar enthalpy, TRANSITION, VOLUME, VOLUMES, WATER-RICH REGION}, isbn = {0378-3812}, url = {://000089031000011}, author = {To, E. C. H. and Westh, P. and Trandum, C. and Hvidt, A. and Koga,Yoshikata} } @article {4679, title = {Compressibilities of aqueous tert-butanol in the water-rich region at 25 degrees C: Partial molar fluctuations and mixing schemes}, journal = {Physical Chemistry Chemical Physics}, volume = {1}, number = {1}, year = {1999}, note = {ISI Document Delivery No.: 179VLTimes Cited: 18Cited Reference Count: 25}, month = {Jan}, pages = {121-126}, type = {Article}, abstract = {We measured the speeds of sound, u, and the densities, d, and, hence, determined the adiabatic compressibilities, kappa(S), of aqueous tert-butanol (TBA) at small increments in mole fraction of TBA, x(TBA). Existing data for heat capacity, C-p, and thermal expansivity, alpha(p), were used to convert kappa(S) to the isothermal compressibilities, kappa(T). Using these kappa(T) data, the normalized volume fluctuations, (V)Delta, and their composition derivative, the partial molar volume fluctuations of TBA, (V)Delta(TBA), (Y. Koga and P. Westh, Bull. Chem. Soc. Jpn., 1996, 69, 1505) were calculated. By using C-p data available in the literature we also calculated the normalized entropy fluctuations, (S)Delta, and the partial molar entropy fluctuations of TBA, (S)Delta(TBA). Furthermore, the density data at 15, 25 and 35 degrees C in the literature were used to evaluate the thermal expansivities, alpha(p), from which the normalized cross (entropy-volume) fluctuations, (SV)Delta, and the partial molar cross-fluctuations of TBA, (SV)Delta(TBA), were calculated. The composition dependence of these fluctuation functions were interpreted in the Light of the mixing schemes in aqueous solutions of TBA and other non-electrolytes and the transition between them (Y. Koga, J. Phys. Chem., 1996, 100, 5172).}, keywords = {2-BUTOXYETHANOL, ALCOHOL, ENTHALPIES, ISOCHORIC HEAT-CAPACITIES, ISOTHERMAL COMPRESSIBILITIES, MIXTURES, NONELECTROLYTES, SOUND, TRANSITION, VOLUMES}, isbn = {1463-9076}, url = {://000079350200017}, author = {Tamura, K. and Osaki, A. and Koga,Yoshikata} } @article {4458, title = {Electronic spectra of YOH and YOD in the visible region: Strong vibronic coupling between the (B)over-tilde(1)II and (C)over-tilde(1)Sigma(+) states}, journal = {Journal of Molecular Spectroscopy}, volume = {196}, number = {1}, year = {1999}, note = {ISI Document Delivery No.: 208RCTimes Cited: 7Cited Reference Count: 41}, month = {Jul}, pages = {45-69}, type = {Article}, abstract = {Laser excitation spectra of yttrium monohydroxide, YOH, have been recorded in the 500-625 nm wavelength region. Rotational analysis of bands of YOH and YOD has shown that the ground state is (X) over tilde(1)Sigma(+), with the structure r(0)(Y-O) = 1.948(6) Angstrom, r(0)(O-H) = 0.920(6) Angstrom; the bending frequency (nu(2), pi) is 313.73 cm(-1) (237.43 cm(-1) in YOD) and the Y-O stretching frequency (nu(3), sigma(+)) is 673.83 cm(-1) (655.34 cm(-1)). Two excited electronic states have been identified; they are assigned as (B) over tilde(1)Pi (16 449 cm(-1)) and (C) over bar(1)Sigma(+) (18 509 cm(-1)). Unusually strong vibronic coupling through the bending vibration occurs between these two states, which causes their vibrational structures to be highly irregular; assignments have only been possible following extensive wavelength-resolved fluorescence experiments. The vibronic coupling raises the bending frequency of the (C) over tilde(1)Sigma(+) state to 457 cm(-1) and reduces that of the lower Born-Oppenheimer component of the (B) over tilde(1)Pi state (which has A{\textquoteright} symmetry in the C, point group) to the extent that the molecule becomes nonlinear, with a potential barrier at the linear configuration of about 120 cm(-1). The presence of the potential barrier is clearly demonstrated by the level structure of YOD, where the Sigma(+) vibronic component of the 010 vibrational level (linear molecule notation) lies 1.4 cm(-1) below the 000 level. The upper Born-Oppenheimer component, which has A " symmetry, is unaffected; its bending frequency is similar to that of the ground state. Perturbations occur in both the (B) over tilde(1)Pi and (C) over tilde(1)Sigma(+) states; some of these represent local interactions between the two of them, but others are caused by higher vibrational levels of lower-lying "dark" electronic states. Over 40 ground state vibrational levels have been identified for both YOH and YOD from the wavelength-resolved fluorescence spectra. (C) 1999 Academic Press.}, keywords = {15-K, laser spectroscopy, METHYLIDYNE, ORBITAL ANGULAR-MOMENTUM, RESONANCE, SYSTEM, TRANSITION, TRIATOMIC-MOLECULES, VANADIUM, WATER}, isbn = {0022-2852}, url = {://000081004300006}, author = {Adam, A. G. and Athanassenas, K. and Gillett, D. A. and Kingston, C. T. and Merer, A. J. and Peers, J. R. D. and Rixon, S. J.} } @article {4686, title = {Excess chemical potentials, excess partial molar enthalpies, entropies, volumes, and isobaric thermal expansivities of aqueous glycerol at 25 degrees C}, journal = {Journal of Solution Chemistry}, volume = {28}, number = {10}, year = {1999}, note = {ISI Document Delivery No.: 247VPTimes Cited: 36Cited Reference Count: 27}, month = {Oct}, pages = {1137-1157}, type = {Article}, abstract = {The vapor pressures p the excess partial molar enthalpies of glycerol He,, the densities d and the thermal expansivities oc, of aqueous glycerol were measured at 25 degrees C. From the vapor pressure data, the excess chemical potential of H2O mu(W)(E) was calculated, assuming that the partial pressure of glycerol Poly is negligibly small. The excess chemical potential of glycerol mu(Gly)(E) was estimated by applying the Gibbs-Duhem relation and these data were used to calculate the excess partial molar entropies S-Gly(E). From the density data, the excess partial molar volumes of glycerol V-Gly(E) and from the thermal expansivity data, the normalized cross fluctuations (SV)Delta, introduced by us earlier, were evaluated. While the detailed manner in which glycerol modifies the molecular arrangement of H2O in its immediate vicinity is yet to be elucidated, the hydrogen bond probability in the bulk H2O away from solute molecules is reduced gradually as the glycerol composition increases to the point where putative presence of icelike patches is no longer possible. Thereupon, a qualitatively different mixing scheme seems to set in.}, keywords = {2-BUTOXYETHANOL, aqueous glycerol, excess partial molar enthalpies and, fluctuations, MIXING SCHEME, MIXTURES, NONELECTROLYTES, normalized cross fluctuations, PERCOLATION, PRESSURES, TERT-BUTANOL, THERMAL EXPANSIVITIES, TRANSITION, vapor pressures, VOLUMES, WATER-RICH REGION}, isbn = {0095-9782}, url = {://000083241900003}, author = {To, E. C. H. and Davies, J. V. and Tucker, M. and Westh, P. and Trandum, C. and Suh, K. S. H. and Koga,Yoshikata} } @article {4422, title = {Intermolecular interactions in tert-butyl alcohol dimethyl sulfoxide H2O: Chemical potentials, partial molar entropies and volumes}, journal = {Journal of Physical Chemistry B}, volume = {102}, number = {26}, year = {1998}, note = {ISI Document Delivery No.: ZY137Times Cited: 13Cited Reference Count: 28}, month = {Jun}, pages = {5182-5195}, type = {Article}, abstract = {The excess chemical potentials, the excess partial molar entropies, and the partial molar volumes in tert-butyl alcohol (TBA)-dimethyl sulfoxide (DMSO)-H2O mixtures were determined. These data, together with previously published excess partial molar enthalpies (Fluid Phase Equilib. 1997, 136, 207) were used to evaluate intermolecular interactions. The TBA-TBA and TBA-DMSO, and DMSO-DMSO interactions were found to be crucially dependent on the composition. The net interaction in terms of chemical potential is very intricate. For example, net interactions of DMSO with a hydrophobic moiety (represented here by TEA) change from attractive to repulsive as the composition changes. This suggests that general discussions of the affinity of DMSO for nonpolar groups (or surfaces) are meaningful only by specifying the composition region. The interactions in terms of enthalpy and entropy are an order of magnitude larger and strongly compensating. Anomalous changes in the enthalpic/entropic interactions and hence qualitative changes in the mixing scheme of the solution, previously described in respective binary TBA-H2O and DMSO-H2O systems, are also apparent in this ternary system. II was found that as the mole fraction, x(D), of DMSO (third component) increases, the transition in mixing scheme occurred at a progressively lower value of x(B). The behavior of partial molar volume indicated that as x(B) increases, the initial increase in the partial molar volume of H2O on increasing x(D), reminiscent to "iceberg formation", diminished. This suggests that existing TEA molecules already made their contribution to the "iceberg formation". The DMSO-DMSO interaction in terms of volume also showed that the transition occurred at a smaller value of x(D) than that for x(B) = 0. The boundary between the two mixing schemes in the present ternary mixture was a straight line in the x(D)-x(B) field, suggesting that the effect of TEA and DMSO on H2O, causing the transition in the mixing scheme, is additive.}, keywords = {AQUEOUS-SOLUTIONS, ENTHALPIES, HYDROPHOBIC INTERACTION, MIXING SCHEME, MIXTURES, NONELECTROLYTES, NONPOLAR SOLUTE PARTICLES, PERCOLATION, TRANSITION, WATER-RICH REGION}, isbn = {1089-5647}, url = {://000074590000026}, author = {Trandum, C. and Westh, P. and Haynes, C. A. and Koga,Yoshikata} } @article {4440, title = {Light scattering study on sol-gel transformation of SiO2 colloid at extremely high concentrations}, journal = {Clays and Clay Minerals}, volume = {46}, number = {2}, year = {1998}, note = {ISI Document Delivery No.: ZU862Times Cited: 5Cited Reference Count: 29}, month = {Apr}, pages = {161-166}, type = {Article}, abstract = {Ludox SiO(2 )sols with a reasonably uniform size of 12 nm and in the high concentration of 10 to 40 wt\% were transformed to gels by lowering the pH. The process from sol to gel, followed by light scattering, did not show a sign of fractal growth within the length scale of observation (>40 nm). Rather, a density fluctuation due to a dynamic (non-equilibrium) disorder was apparent. Together with the results of viscosity measurements, it was concluded that the process consists of 3 stages: 1) A dynamic (non-equilibrium) density fluctuation grows rapidly. 2) Such density fluctuation acquires some order. 3) The entire bulk loses fluidity and becomes a macroscopic gel.}, keywords = {AGGREGATION, DENSITY FLUCTUATION, GLASS, GROWTH, light scattering study, PARTICLES, SILICA, SiO2 colloids, sol-gel transformation, TRANSITION, X-RAY-SCATTERING}, isbn = {0009-8604}, url = {://000074243100006}, author = {Xu, Y. N. and Koga,Yoshikata} } @article {4427, title = {The pure rotational spectrum of yttrium monobromide}, journal = {Journal of Chemical Physics}, volume = {109}, number = {13}, year = {1998}, note = {ISI Document Delivery No.: 123YFTimes Cited: 14Cited Reference Count: 51}, month = {Oct}, pages = {5439-5445}, type = {Article}, abstract = {The pure rotational spectrum of the X (1)Sigma(+) ground electronic state of yttrium monobromide has been measured. This is the first high-resolution spectrum recorded for this molecule. Transitions in the ground and first excited vibrational states have been measured for both the (YBr)-Br-79 and (YBr)-Br-81 isotopomers. Equilibrium rotational parameters have been determined and an equilibrium bond distance has been calculated. Vibrational parameters have been estimated. Hyperfine structure due to the bromine nuclei has been observed and nuclear quadrupole and nuclear spin-rotation constants have been determined. These parameters have been used to investigate the ionic character of the Y-Br bond and comparisons have been made to several alkali and alkaline earth metal bromide species. (C) 1998 American Institute of Physics. [S0021-9606(98)02337-X].}, keywords = {BAND SYSTEM, LASER-INDUCED FLUORESCENCE, MOLECULAR-BEAM, PUMP PROBE, RF DOUBLE-RESONANCE, SPECTROSCOPY, STARK, STATE, TRANSITION, YCL, YF}, isbn = {0021-9606}, url = {://000076152700032}, author = {Walker, K. A. and Gerry, M. C. L.} } @article {4130, title = {The quadrature discretization method (QDM) in the calculation of the rotational-vibrational transitions in rare gas dimers}, journal = {Theochem-Journal of Molecular Structure}, volume = {391}, number = {1-2}, year = {1997}, note = {ISI Document Delivery No.: WU757Times Cited: 3Cited Reference Count: 38}, month = {Feb}, pages = {131-139}, type = {Article}, abstract = {A discretization method referred to as the Quadrature Discretization Method (QDM) is employed for the determination of the rotational-vibrational states of the inert gas dimers. The QDM is based on the discretization of the wave function on a grid of points that coincide with the points of a quadrature. The quadrature is based on a set of non-classical polynomials orthogonal with respect to a weight function determined by the potential function in the Schroedinger equation. In this paper, the weight functions used in the solution of the Schroedinger equation are related to the ground state wavefunctions of the Morse potential that approximates the potential of interest. Calculations are carried out for vibrational energy levels for HF modelled with a Morse potential. Excellent agreement is obtained with the known spectrum of the Morse potential. The rate of convergence of the eigenvalues and the eigenfunctions of the Schroedinger equation is very rapid with this approach. The vibrational and rotational transitions for the rare gas dimers are calculated and compared with the results reported recently by Ogilvie and Wang (J. Mol. Struc., 291 (1993) 313). (C) 1997 Elsevier Science B.V.}, keywords = {AR-XE, COEFFICIENTS, DISCRETE-VARIABLE REPRESENTATION, NE-KR, ORDINATE METHOD, POTENTIALS, quadrature discretion method, QUANTUM-MECHANICS, rare gas dimer, rotation-vibration, SCHRODINGER-EQUATION, Schroedinger equation, SPECTRA, STATES, TRANSITION}, isbn = {0166-1280}, url = {://A1997WU75700014}, author = {Shizgal, B. D.} } @article {3763, title = {Driving forces for DNA adsorption to silica in perchlorate solutions}, journal = {Journal of Colloid and Interface Science}, volume = {181}, number = {2}, year = {1996}, note = {ISI Document Delivery No.: UZ536Times Cited: 112Cited Reference Count: 43}, month = {Aug}, pages = {635-644}, type = {Article}, abstract = {The adsorption of both plasmid and chromosomal duplex DNA to silica is investigated with the aim of determining the dominant forces involved in the binding reaction. Changes in the initial slopes and plateau values of adsorption isotherms for DNA on microcrystalline silica particles are used to establish the sensitivity of the binding reaction to ionic strength, temperature and pH, and DNA size and conformation. Binding is driven by an increase in entropy, with little or no enthalpic contribution. Adsorption isotherm results indicate that three effects, namely: (i) shielded intermolecular electrostatic forces, (ii) dehydration of the DNA and silica surfaces, and (iii) intermolecular hydrogen bond formation in the DNA-silica contact layer, make the dominant contributions to the overall driving force for adsorption. (C) 1996 Academic Press, Inc.}, keywords = {adsorption isotherms, ARRAYS, CHIPS, CONFORMATION, DNA, DNA adsorption, DNA binding, DNA PURIFICATION, DNA-silica interactions, ELECTROPHORESIS, GLOBULAR-PROTEINS, PLASMID DNA, PURIFICATION, SURFACES, TRANSITION}, isbn = {0021-9797}, url = {://A1996UZ53600031}, author = {Melzak, K. A. and Sherwood, C. S. and Turner, R. F. B. and Haynes, C. A.} } @article {3830, title = {Excess partial molar enthalpies of alkane-mono-ols in aqueous solutions}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {74}, number = {5}, year = {1996}, note = {ISI Document Delivery No.: UP791Times Cited: 50Cited Reference Count: 29}, month = {May}, pages = {713-721}, type = {Article}, abstract = {Excess partial molar enthalpies, H-A(E), of methanol, ethanol, and 1- and 2-propanols in aqueous solutions were measured directly, accurately, and in small increments in mole fraction at 25 degrees C. From these data, the solute-solute enthalpic interactions, H-AA(E) = N(partial derivative H-A(E)/partial derivative n(A)), were evaluated for each alcohol. These data indicate that three distinctively different mixing schemes, I, II, and III exist, as was the case for aqueous 2-butoxyethanol previously studied in our laboratory. The transition from mixing scheme I to II appears to take place gradually within a small composition range. As the hydrophobic moiety becomes smaller from 2-butoxyethanol to methanol, the locus of the transition moves to a higher value in mole fraction of the alcohol. At the same time, the range of transition becomes wider and the solute-solute enthalpic interaction weaker.}, keywords = {1-PROPANOL, 2-BUTOXYETHANOL, 2-PROPANOL, 25-DEGREES-C, BUTYL ALCOHOL-SOLUTIONS, CONCENTRATION FLUCTUATIONS, enthalpic interaction, ENTROPIES, ETHANOL, excess partial molar enthalpies in aqueous solutions, FREE-ENERGIES, METHANOL, MIXING SCHEME, TERT-BUTANOL MIXTURES, TRANSITION, transition of, WATER-RICH REGION}, isbn = {0008-4042}, url = {://A1996UP79100011}, author = {Tanaka, S. H. and Yoshihara, H. I. and Ho, A. W. C. and Lau, F. W. and Westh, P. and Koga,Yoshikata} } @article {3600, title = {The near infrared electronic spectrum of tungsten methylidyne, WCH}, journal = {Journal of Chemical Physics}, volume = {105}, number = {15}, year = {1996}, note = {ISI Document Delivery No.: VM554Times Cited: 19Cited Reference Count: 29}, month = {Oct}, pages = {6168-6182}, type = {Article}, abstract = {The laser excitation spectrum of tungsten methylidyne, WCH, has been recorded in the 12 000-15 400 cm(-1) region. A total of 14 vibronic bands of WCH and 16 bands of WCD have been observed in this region. Rotational analysis shows that the ground state is (X) over tilde 3/2((2) Delta), with the substitution structure r(0)(W=C)=1.7366(5) Angstrom and r(0)(C-H)=1.076(5) Angstrom. The excited vibronic levels have been assigned, on the basis of their WCH/WCD isotope shifts and their wavelength resolved fluorescence patterns, to three electronic states, (A) over tilde 3/2((2) Delta), (B) over tilde 1/2((2) Pi), and (C) over tilde 5/2(2 Phi), at 12 090, 13 392, and 14 110 cm(-1), respectively. The wavelength resolved fluorescence spectra have also established the low-lying vibrational levels of the ground state. The ground state bending fundamental lies at 660 cm(-1), while the W-C stretching frequency is 1006 cm(-1); the corresponding frequencies in WCD are 501 cm(-1) and 953 cm(-1), respectively. No evidence for the C-H stretching frequency has been found. Emission has also been observed to a low-lying electronic state, 813 cm(-1) above the (X) over tilde 3/2 state. The pattern of rotationally resolved emission to this state clearly indicates that it is a (4) Sigma(1/2) state. Its bending frequency is 612 cm(-1), and its W-C stretching frequency is 971 cm(-1), indicating a slightly longer bond length than in the (X) over tilde 3/2 state. High resolution cw laser spectra of the (0,0) bands of the two lowest excited electronic states [(A) over tilde 3/2((2) Delta) and (B) over tilde 1/2((2) Pi)] reveal a small splitting of the four principal tungsten isotopes (W-182, W-183, W-184, and W-186) which serves to confirm the presence of tungsten in the carrier. Hyperfine splitting associated with the W-183 nucleus (I = 1/2) has been observed for the (0,0) band of the (A) over tilde 3/2- (X) over tilde 3/2 system, allowing the electron configuration of the ground state to be elucidated. (C) 1996 American Institute of Physics.}, keywords = {COMPLEXES, FREE-RADICALS, GAS-PHASE, HYPERFINE-STRUCTURE, LASER-INDUCED FLUORESCENCE, SPECTROSCOPY, STATES, SYSTEM, TRANSITION, ZNCH3}, isbn = {0021-9606}, url = {://A1996VM55400009}, author = {Barnes, M. and Gillett, D. A. and Merer, A. J. and Metha, G. F.} } @article {3281, title = {DENSITY-FUNCTIONAL CALCULATIONS OF FERMI CONTACT HYPERFINE COUPLING PARAMETERS}, journal = {Chemical Physics Letters}, volume = {234}, number = {4-6}, year = {1995}, note = {ISI Document Delivery No.: QK799Times Cited: 29Cited Reference Count: 31}, month = {Mar}, pages = {405-412}, type = {Article}, abstract = {Fermi contact parameters are calculated with a range of one-particle basis sets and functionals. The parameters are determined at all nuclei in the following eleven radicals: C2H3, C2H2F, CH, NH+, NH, OH+, OH, FH, FF-, CN, NO2. Results show that using Becke{\textquoteright}s new three-parameter exchange functional leads to improved agreement with experiment.}, keywords = {ACCURATE, APPROXIMATION, CORRELATED MOLECULAR CALCULATIONS, DOUBLE-RESONANCE, EXCHANGE-ENERGY, GAUSSIAN-BASIS SETS, MAGNETIC-RESONANCE SPECTRUM, optical, SPECTROSCOPY, TRANSITION}, isbn = {0009-2614}, url = {://A1995QK79900022}, author = {Cohen, M. J. and Chong, D. P.} } @article {3412, title = {EXCESS PARTIAL MOLAR ENTHALPIES, ENTROPIES, GIBBS ENERGIES, AND VOLUMES IN AQUEOUS DIMETHYLSULFOXIDE}, journal = {Journal of Solution Chemistry}, volume = {24}, number = {1}, year = {1995}, note = {ISI Document Delivery No.: QF279Times Cited: 60Cited Reference Count: 20}, month = {Jan}, pages = {89-102}, type = {Article}, abstract = {The excess partial molar enthalpies, the vapor pressures, and the densities of dimethylsulfoxide (DMSO) - H2O mixtures were measured and the excess partial molar Gibbs energies and the partial molar volumes were calculated for DMSO and for H2O. The values of the excess partial molar Gibbs energies for both DMSO and H2O are negative over the entire composition range. The results for the water-rich region indicated that the presence of DMSO enhances the hydrogen bond network of H2O. Unlike monohydric alcohols, however, the solute-solute interaction is repulsive in terms of the Gibbs energy. This was a result of the fact that the repulsion among solutes in terms of enthalpy surpassed the attraction in terms of entropy. The data in the DMSO-rich region suggest that DMSO molecules form clusters which protect H2O molecules from exposure to the nonpolar alkyl groups of DMSO.}, keywords = {2-BUTOXYETHANOL, 25-DEGREES-C, AQUEOUS DIMETHYLSULFOXIDE, DIMETHYL-SULFOXIDE, ENTROPIES, excess partial molar enthalpies, GIBBS ENERGIES AND VOLUMES, HEAT-CAPACITIES, LIQUID-MIXTURES, MIXING SCHEME, RANGE, SOLUTE-SOLUTE INTERACTION, TRANSITION, WATER-RICH REGION}, isbn = {0095-9782}, url = {://A1995QF27900007}, author = {Lai, J. T. W. and Lau, F. W. and Robb, D. and Westh, P. and Nielsen, G. and Trandum, C. and Hvidt, A. and Koga,Yoshikata} } @article {3400, title = {FLUCTUATIONS IN AQUEOUS-SOLUTIONS OF SOME HYDROPHOBIC SOLUTES}, journal = {Chemical Physics Letters}, volume = {240}, number = {4}, year = {1995}, note = {ISI Document Delivery No.: RG423Times Cited: 13Cited Reference Count: 33}, month = {Jun}, pages = {340-344}, type = {Article}, abstract = {The entropy fluctuation in liquids and solutions is most conveniently normalized to the coarse-grained volume. Hence, [(Delta S/V)(2)] = RC(p)/V-m(2) and [(Delta S/V)(Delta N/N)] = RT alpha(p)/V-m. It was shown to be useful if the response functions, C-p, kappa(T) and alpha(p), and the fluctuations derived from them, were discussed separately in contrasting the peculiar nature of liquid H2O against a typical van der Waals liquid, benzene. The composition dependence of these fluctuations was examined in aqueous solutions of typical hydrophobic solutes, 2-butoxyethanol, 2-butanone and tert-butanol. It was concluded that the above solutes reduce the hydrogen bond probability in H2O up to the crossover point of mixing scheme, x(i)(c).}, keywords = {2-BUTOXYETHANOL, 25-DEGREES-C, FREE-ENERGIES, HEAT-CAPACITIES, MIXING SCHEME, PARTIAL MOLAR ENTHALPIES, TERT-BUTANOL MIXTURES, TRANSITION, VOLUMES, WATER-RICH REGION}, isbn = {0009-2614}, url = {://A1995RG42300015}, author = {Koga,Yoshikata} } @article {3402, title = {IONIC-CONDUCTIVITY IN THE WATER-RICH REGION OF AQUEOUS 2-BUTOXYETHANOL}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {73}, number = {8}, year = {1995}, note = {ISI Document Delivery No.: RZ492Times Cited: 4Cited Reference Count: 22}, month = {Aug}, pages = {1294-1297}, type = {Article}, abstract = {Ionic conductivities of HCl, KOH, and KCl were measured in aqueous solutions of 2-butoxyethanol (BE) at 25 degrees C. The quantity, Lambda(j){\textquoteright} = sigma/x(j), which is almost proportional to the molar conductivity, was extrapolated to the infinite dilution x(j) {\textendash}> 0. sigma is the conductivity and x(j) is the mole fraction of j(= HCl, KOH, or KCl). The plots of (0) Lambda(j){\textquoteright}, the value of Lambda(j){\textquoteright} extrapolated to infinite dilution, against x(BE) showed a change in slope at x(BE) = 0.0175. The previous work from this laboratory indicated that the mixing scheme changes qualitatively at the same locus, x(BE) = 0.0175. By mixing scheme we simply mean the way in which BE and H2O molecules mix with each other. Assuming additivity in (0)h(j){\textquoteright} in terms of constituent ions, those values for H+OH- were calculated. Plots of (0) Lambda(H+OH-){\textquoteright} thus calculated as a function of x(BE) in the water-rich region, 0 < x(BE) < 0.0175, suggest that the hydrogen bond probability decreases in the bulk of solution, as x(BE) increases.}, keywords = {AQUEOUS 2-BUTOXYETHANOL, BOND NETWORK, HYDROGEN, IONIC CONDUCTIVITIES, MIXING SCHEME, MIXING SCHEMES, MIXTURES, PARTIAL MOLAR ENTHALPIES, SCATTERING, TRANSITION, VOLUMES}, isbn = {0008-4042}, url = {://A1995RZ49200008}, author = {Koga,Yoshikata and Loo, V. J. and Puhacz, K. T.} } @article {3236, title = {ISOTOPE AND HYPERFINE-STRUCTURE IN THE ORANGE SYSTEM OF FEO - EVIDENCE FOR 2 5-DELTA(I) EXCITED-STATES}, journal = {Journal of Molecular Spectroscopy}, volume = {170}, number = {2}, year = {1995}, note = {ISI Document Delivery No.: QT231Times Cited: 29Cited Reference Count: 27}, month = {Apr}, pages = {449-465}, type = {Article}, abstract = {The orange system of FeO has been reinvestigated using low-temperature molecular beam laser-induced fluorescence spectra, obtained by supersonic jet cooling. Two new weak bands have been found, and analyses of some of the previously known bands extended. Measurements of the Fe-54-Fe-56 isotope shifts have been made for most of the bands, and the hyperfine structure of the low-J lines has been recorded for two of the strongest bands of (FeO)-Fe-57. The isotope shifts are consistent with the presence of two (5) Delta(i)-(5) Delta(i) transitions lying within 1000 cm(-1); the origins of the Omega = 4 spin components lie at 5583 and 6110 Angstrom, respectively. The hyperfine patterns and the spin-orbit structure indicate that the upper state electron configurations are (3d delta)(3) (3d pi)(2) (3d sigma)(1), (D5 Delta(i), 5583 Angstrom) and O(2p pi)(3) (4s sigma)(1) (3d delta)(3)(3d pi)(3), (D{\textquoteright}(5) Delta(i), 6110 Angstrom). The bond length in the D{\textquoteright} state (r(0) = 1.654 Angstrom) has been obtained from a deperturbation of the 6110 Angstrom band; it is only 0.035 Angstrom longer than in the ground state, which indicates that electron promotion between the two pi orbitals, nominally O(2p pi) and Fe(3d pi), has only a small effect on the strength of the bonding. The new isotope data still do not clarify the vibrational assignments of the higher levels, which are disorganized by extensive electronic perturbations. (C) 1995 Academic Press, Inc.}, keywords = {COO, ELECTRONIC STATES, FOURIER-TRANSFORM SPECTROSCOPY, GROUND-STATE, MOLECULES, PARAMETERS, TRANSITION}, isbn = {0022-2852}, url = {://A1995QT23100013}, author = {Barnes, M. and Fraser, M. M. and Hajigeorgiou, P. G. and Merer, A. J.} } @article {3330, title = {THE NOVEL PHOTOCHEMICAL BEHAVIOR OF TRIPTYCENE-1,4-QUINONE}, journal = {Tetrahedron Letters}, volume = {36}, number = {12}, year = {1995}, note = {ISI Document Delivery No.: QP020Times Cited: 8Cited Reference Count: 10}, month = {Mar}, pages = {2025-2028}, type = {Article}, abstract = {Triptycene-1,4-quinone (1) reacts photochemically in solution to give different products depending on the solvent employed and on the presence or absence of oxygen. The structures of the photoproducts have been elucidated by spectroscopic methods, independent synthesis and single crystal X-ray diffractometry, and possible mechanistic pathways leading to their formation are presented and discussed. Unexpectedly, quinone 1 was found to be photochemically inert in the crystalline state. The X-ray crystal structure of 1 reveals the probable reason for this behavior.}, keywords = {10-DIHYDRO-9, 10-ORTHO-BENZENOANTHRACENE-1, 4-DIONES, 9, ABSTRACTION, DERIVATIVES, INTRAMOLECULAR CHARGE-TRANSFER, TRANSITION}, isbn = {0040-4039}, url = {://A1995QP02000014}, author = {Fu, T. Y. and Gamlin, J. N. and Olovsson, G. and Scheffer, J. R. and Trotter, J. and Young, D. T.} } @article {3330, title = {THE NOVEL PHOTOCHEMICAL BEHAVIOR OF TRIPTYCENE-1,4-QUINONE}, journal = {Tetrahedron Letters}, volume = {36}, number = {12}, year = {1995}, note = {ISI Document Delivery No.: QP020Times Cited: 8Cited Reference Count: 10}, month = {Mar}, pages = {2025-2028}, type = {Article}, abstract = {Triptycene-1,4-quinone (1) reacts photochemically in solution to give different products depending on the solvent employed and on the presence or absence of oxygen. The structures of the photoproducts have been elucidated by spectroscopic methods, independent synthesis and single crystal X-ray diffractometry, and possible mechanistic pathways leading to their formation are presented and discussed. Unexpectedly, quinone 1 was found to be photochemically inert in the crystalline state. The X-ray crystal structure of 1 reveals the probable reason for this behavior.}, keywords = {10-DIHYDRO-9, 10-ORTHO-BENZENOANTHRACENE-1, 4-DIONES, 9, ABSTRACTION, DERIVATIVES, INTRAMOLECULAR CHARGE-TRANSFER, TRANSITION}, isbn = {0040-4039}, url = {://A1995QP02000014}, author = {Fu, T. Y. and Gamlin, J. N. and Olovsson, G. and Scheffer, J. R. and Trotter, J. and Young, D. T.} } @article {3403, title = {Speeds of sound and isothermal compressibilities in the water-rich region of aqueous 2-butoxyethanol and 2-butanone at 25 degrees C}, journal = {Journal of Solution Chemistry}, volume = {24}, number = {11}, year = {1995}, note = {ISI Document Delivery No.: TV702Times Cited: 8Cited Reference Count: 25}, month = {Nov}, pages = {1125-1133}, type = {Article}, abstract = {Speeds of sound were measured at 25 degrees C in the water-rich region of aqueous 2-butoxyethanol (BE) and 2-butanone (BUT). Density, heat capacity, and thermal expansivity data available in literature were used to calculate isothermal compressibilities, kappa(T). The composition derivative, N(partial derivative kappa(T)/partial derivative n(B)), a third derivative of Gibbs free energy, showed a peak anomaly at x(BE) = 0.0175 for BE-H2O, and bend at x(BUT) = 0.033 for BUT-H2O. n(B) (n(BE) or n(BUT)) is the amount of the solute and x(BE) and x(BUT) are the respective mole fractions. The location of these anomalies were the same as those of other third derivatives found earlier for the same aqueous solutions. These anomalies were shown earlier to mark the transition point across which the mixing scheme changes in a qualitative fashion.}, keywords = {2-BUTANONE, 2-BUTOXYETHANOL, anomaly in the third derivative, aqueous solutions, ENTHALPIES, HEAT-CAPACITIES, isothermal compressibility, MIXING SCHEME, MIXTURES, of mixing scheme, PARTIAL MOLAR VOLUMES, RANGE, speed of sound, SYSTEMS, TRANSITION}, isbn = {0095-9782}, url = {://A1995TV70200004}, author = {Koga,Yoshikata and Tamura, K. and Murakami, S.} } @article {3077, title = {ANOMALOUS X-RAY-SCATTERING FROM AQUEOUS 2-BUTOXYETHANOL AT X(BE)=0.06 NEAR FREEZING}, journal = {Chemical Physics Letters}, volume = {228}, number = {1-3}, year = {1994}, note = {ISI Document Delivery No.: PJ977Times Cited: 5Cited Reference Count: 31}, month = {Sep}, pages = {53-56}, type = {Article}, abstract = {{Small angle X-ray scattering was measured from aqueous 2-butoxyethanol of mole fraction x(BE) = 0.06 at 273, 278 and 298 K. Anomalously strong scattering was observed at 273 and 278 K. The scattering intensity I is proportional to s(-3) in the range s<0.06 Angstrom(-1), where s is the momentum transfer of scattering}, keywords = {CONCENTRATION FLUCTUATIONS, CORRELATION LENGTH, KIRKWOOD-BUFF PARAMETERS, LIGHT-SCATTERING, mixing, MIXTURES, PARTIAL MOLAR ENTHALPIES, SCHEME, TERT-BUTYL ALCOHOL, TRANSITION, WATER-RICH REGION}, isbn = {0009-2614}, url = {://A1994PJ97700008}, author = {Koga,Yoshikata and Nishikawa, K. and Yoshino, K. and Tanaka, I. and Xu, Y. N. and Amemiya, Y.} } @article {3007, title = {EXCESS PARTIAL MOLAR VOLUMES AND THERMAL EXPANSIVITIES IN THE WATER-RICH REGION OF AQUEOUS 2-BUTANONE}, journal = {Journal of Solution Chemistry}, volume = {23}, number = {2}, year = {1994}, note = {ISI Document Delivery No.: NB508Times Cited: 8Cited Reference Count: 22Symposium in Honor of Donald Patterson on His 65th Birthday, at the 76th Congress of the Canadian-Society-for-ChemistryMAY 31-JUN 03, 1993SHERBROOKE, CANADACANADIAN SOC CHEM}, month = {Feb}, pages = {339-349}, type = {Proceedings Paper}, abstract = {Excess partial molar volumes of 2-butanone V(m)E(B) and thermal expansivities alpha(p) were measured in the water-rich region of aqueous 2-butanone. The composition derivatives of both quantities showed anomalies at about X(B) = 0.033 (x(B) is the mole fraction of B). (partial derivative V(m)E(B)/partial derivative n(B))p,T,nW showed a step anomaly, while (partial derivative alpha(p)/partial derivatives n(B))p,T,nw exhibited a peak anomaly. The compositions at which these anomalies occurred match those of the step anomalies observed earlier in (partial derivative H(m)E(B)/partial derivative n(B))p,T,nW and (partial derivative S(m)E(B)/partial derivative n(B))p,T,nW in aqueous 2-butanone. These results are discussed in comparison with those obtained previously for aqueous 2-butoxyethanol.}, keywords = {2-BUTANONE, 2-BUTOXYETHANOL, 25-DEGREES-C, ANOMALIES IN 3RD DERIVATIVES, AQUEOUS, DERIVATIVES, ENTHALPIES, EXCESS PARTIAL MOLAR VOLUMES, fluctuations, FREE-ENERGIES, HEAT-CAPACITIES, MIXING SCHEME, OF GIBBS FREE ENERGY, TERT-BUTANOL MIXTURES, THERMAL EXPANSIVITIES, TRANSITION, TRANSITION OF MIXING SCHEME}, isbn = {0095-9782}, url = {://A1994NB50800016}, author = {Davies, J. V. and Fooks, R. and Koga,Yoshikata} } @article {3078, title = {MIXING SCHEMES AND LIQUID-SOLID PHASE-DIAGRAM IN THE WATER-RICH REGION OF AQUEOUS 2-BUTOXYETHANOL}, journal = {Bulletin of the Chemical Society of Japan}, volume = {67}, number = {9}, year = {1994}, note = {ISI Document Delivery No.: PM797Times Cited: 11Cited Reference Count: 28}, month = {Sep}, pages = {2393-2397}, type = {Article}, abstract = {Liquid-solid phase diagram was determined in the water-rich region of aqueous 2-butoxyethanol. A solid addition compound was suggested with the composition x(BE)add = 0.0260, which melts incongruently at 269.5 K. The mixing scheme boundary separating two regions in the single liquid phase domain (Chem. Phys. Lett., 217, 245 (1994) was found to cross the incongruent melting point of the above solid addition compound.}, keywords = {BEHAVIOR, COEFFICIENTS, LIGHT-SCATTERING, MIXTURES, PARTIAL MOLAR ENTHALPIES, TEMPERATURES, TRANSITION, VOLUMES}, isbn = {0009-2673}, url = {://A1994PM79700008}, author = {Koga,Yoshikata and Tanaka, T. and Atake, T. and Westh, P. and Hvidt, A.} } @article {2987, title = {ROTATIONAL STRUCTURE AND PERTURBATIONS IN THE BETA-4-PI-CHI-4-SIGMA- (1, 0) BAND OF VO}, journal = {Journal of Molecular Spectroscopy}, volume = {163}, number = {2}, year = {1994}, note = {ISI Document Delivery No.: MW279Times Cited: 21Cited Reference Count: 25}, month = {Feb}, pages = {443-458}, type = {Article}, keywords = {CRO, FOURIER-TRANSFORM SPECTROSCOPY, laser spectroscopy, MOLECULES, PARAMETERS, STATES, SYSTEM, TRANSITION}, isbn = {0022-2852}, url = {://A1994MW27900012}, author = {Cheung, A. S. C. and Hajigeorgiou, P. G. and Huang, G. and Huang, S. Z. and Merer, A. J.} } @article {2993, title = {STRUCTURE OF 2-COMPONENT CLUSTERS}, journal = {Journal of Chemical Physics}, volume = {101}, number = {3}, year = {1994}, note = {ISI Document Delivery No.: NY002Times Cited: 43Cited Reference Count: 17}, month = {Aug}, pages = {2432-2445}, type = {Article}, abstract = {{Phase separation in binary liquid Lennard-Jones clusters is investigated employing computer simulation methods. Clusters ranging in size from 50 to 240 particles are considered with special emphasis on systems with equal numbers of A and B particles. Cluster morphology is systematically explored by varying the ratios}, keywords = {MOLECULAR-DYNAMICS, SIMULATIONS, TRANSITION}, isbn = {0021-9606}, url = {://A1994NY00200071}, author = {Clarke, A. S. and Kapral, R. and Patey, G. N.} } @article {2791, title = {OLIGOMETALLIC COBALT 3,5-DIMETHYLPYRAZOLATE COMPLEXES - SYNTHESIS, STRUCTURAL AND MAGNETIC STUDIES}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {71}, number = {9}, year = {1993}, note = {ISI Document Delivery No.: MC957Times Cited: 28Cited Reference Count: 25}, month = {Sep}, pages = {1425-1436}, type = {Article}, abstract = {{Three oligometallic 5-dimethylpyrazolate (dmpz) bridged Co(II) compounds have been synthesized and characterized spectroscopically: dimeric [Co(dmpz)2(Hdmpz)]2. the related oligometallic compound, Co(dmpz)2 . 0.344(Hdmpz), and the trimetallic [Co(dmpz)2Cl(Hdmpz)]2Co. The first and last of these compounds have been studied magnetically and by single crystal X-ray diffraction. Crystals of [Co(dmpz)2(Hdmpz)]2 are orthorhombic, = 17.022(1)}, keywords = {CRYSTAL-STRUCTURE, LOW-SPIN, METAL PYRAZOLATE POLYMERS, MOLECULAR-STRUCTURE, THIOCYANATE COORDINATION-COMPOUNDS, TRANSITION}, isbn = {0008-4042}, url = {://A1993MC95700021}, author = {Ehlert, M. K. and Rettig, S. J. and Storr, A. and Thompson, R. C. and Trotter, J.} } @article {2791, title = {OLIGOMETALLIC COBALT 3,5-DIMETHYLPYRAZOLATE COMPLEXES - SYNTHESIS, STRUCTURAL AND MAGNETIC STUDIES}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {71}, number = {9}, year = {1993}, note = {ISI Document Delivery No.: MC957Times Cited: 28Cited Reference Count: 25}, month = {Sep}, pages = {1425-1436}, type = {Article}, abstract = {{Three oligometallic 5-dimethylpyrazolate (dmpz) bridged Co(II) compounds have been synthesized and characterized spectroscopically: dimeric [Co(dmpz)2(Hdmpz)]2. the related oligometallic compound, Co(dmpz)2 . 0.344(Hdmpz), and the trimetallic [Co(dmpz)2Cl(Hdmpz)]2Co. The first and last of these compounds have been studied magnetically and by single crystal X-ray diffraction. Crystals of [Co(dmpz)2(Hdmpz)]2 are orthorhombic, = 17.022(1)}, keywords = {CRYSTAL-STRUCTURE, LOW-SPIN, METAL PYRAZOLATE POLYMERS, MOLECULAR-STRUCTURE, THIOCYANATE COORDINATION-COMPOUNDS, TRANSITION}, isbn = {0008-4042}, url = {://A1993MC95700021}, author = {Ehlert, M. K. and Rettig, S. J. and Storr, A. and Thompson, R. C. and Trotter, J.} } @article {2791, title = {OLIGOMETALLIC COBALT 3,5-DIMETHYLPYRAZOLATE COMPLEXES - SYNTHESIS, STRUCTURAL AND MAGNETIC STUDIES}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {71}, number = {9}, year = {1993}, note = {ISI Document Delivery No.: MC957Times Cited: 28Cited Reference Count: 25}, month = {Sep}, pages = {1425-1436}, type = {Article}, abstract = {{Three oligometallic 5-dimethylpyrazolate (dmpz) bridged Co(II) compounds have been synthesized and characterized spectroscopically: dimeric [Co(dmpz)2(Hdmpz)]2. the related oligometallic compound, Co(dmpz)2 . 0.344(Hdmpz), and the trimetallic [Co(dmpz)2Cl(Hdmpz)]2Co. The first and last of these compounds have been studied magnetically and by single crystal X-ray diffraction. Crystals of [Co(dmpz)2(Hdmpz)]2 are orthorhombic, = 17.022(1)}, keywords = {CRYSTAL-STRUCTURE, LOW-SPIN, METAL PYRAZOLATE POLYMERS, MOLECULAR-STRUCTURE, THIOCYANATE COORDINATION-COMPOUNDS, TRANSITION}, isbn = {0008-4042}, url = {://A1993MC95700021}, author = {Ehlert, M. K. and Rettig, S. J. and Storr, A. and Thompson, R. C. and Trotter, J.} } @article {2930, title = {ORIENTATIONAL ORDER IN SIMPLE DIPOLAR FLUIDS - DENSITY-FUNCTIONAL THEORY AND ABSOLUTE-STABILITY CONDITIONS}, journal = {Physical Review E}, volume = {47}, number = {1}, year = {1993}, note = {ISI Document Delivery No.: KY134Times Cited: 59Cited Reference Count: 29}, month = {Jan}, pages = {506-512}, type = {Article}, abstract = {The formation of ferroelectric liquid crystals by simple dipolar models is investigated using density-functional theory and absolute-stability analysis. It is emphasized that for such systems well defined results can only be found by specifying exactly how the long-range dipolar interactions are treated. Explicit formal expressions are derived for mean-reaction-field boundary conditions and these are combined with integral-equation approximations in order to obtain numerical results for fluids of dipolar hard and soft spheres. The calculations predict isotropic-to-ferroelectric-nematic transitions in qualitative agreement with computer simulations. The quantitative agreement, however, is rather poor.}, keywords = {COMPUTER-SIMULATION, ELECTROSTATIC SYSTEMS, equation, HARD-SPHERES, INVARIANT EXPANSION, MEAN SPHERICAL MODEL, ORNSTEIN-ZERNIKE, PERIODIC BOUNDARY-CONDITIONS, POLAR SYSTEMS, TRANSITION}, isbn = {1063-651X}, url = {://A1993KY13400062}, author = {Wei, D. Q. and Patey, G. N. and Perera, A.} } @article {7384, title = {EXCESS PARTIAL MOLAR FREE-ENERGIES, ENTHALPIES, AND ENTROPIES IN 2-BUTANONE-H2O MIXTURES - SOLUTE SOLUTE INTERACTIONS}, journal = {Journal of Physical Chemistry}, volume = {96}, number = {24}, year = {1992}, note = {ISI Document Delivery No.: KA298Times Cited: 12Cited Reference Count: 19}, month = {Nov}, pages = {10025-10029}, type = {Article}, abstract = {The excess partial molar enthalpies, H(m)E(i), in 2-butanone (BUT)-H2O mixtures were measured at 4.20, 20.00, and 25.00-degrees-C (i = BUT or H2O). The vapor pressures were also measured by a static method at 20.00 and 25.00-degrees-C. From the latter data, the partial pressures and hence the excess partial molar Gibbs free energies, G(m)E(i), were calculated by the method. The excess partial molar entropies, S(m)E(i), were then calculated at 20.00 and 25.00-degrees-C. From the composition derivatives of these partial molar quantities, the nature of the solute-solute interactions was discussed in relation to the global information about the mixture: existence of phase separation, the way in which the phase boundary slants, and existence of azeotropy and addition compound.}, keywords = {2-BUTOXYETHANOL, 25-DEGREES-C, BUTYL ALCOHOL, MIXING SCHEME, SCATTERING, TERT-BUTANOL MIXTURES, TRANSITION, WATER}, isbn = {0022-3654}, url = {://A1992KA29800080}, author = {Wong, T. Y. H. and Wongmoon, K. C. and Beach, L. J. and Chuang, Y. F. and Koga,Yoshikata} } @article {7266, title = {INTRACAVITY LASER SPECTROSCOPY OF VO - HYPERFINE PARAMETERS AND ELECTRON CONFIGURATION OF THE B4-PI STATE}, journal = {Journal of Molecular Spectroscopy}, volume = {153}, number = {1-2}, year = {1992}, note = {ISI Document Delivery No.: HT478Times Cited: 17Cited Reference Count: 22}, month = {May-Jun}, pages = {32-40}, type = {Article}, keywords = {FLUORESCENCE, MOLECULES, SYSTEM, TRANSITION}, isbn = {0022-2852}, url = {://A1992HT47800004}, author = {Huang, G. I. and Merer, A. J. and Clouthier, D. J.} } @article {7130, title = {THE CRYSTALLIZATION OF ALKALI-HALIDES FROM AQUEOUS-SOLUTION - AN APPLICATION OF DENSITY-FUNCTIONAL THEORY}, journal = {Journal of Chemical Physics}, volume = {95}, number = {1}, year = {1991}, note = {ISI Document Delivery No.: FT847Times Cited: 3Cited Reference Count: 23}, month = {Jul}, pages = {485-493}, type = {Article}, abstract = {Density-functional theory is applied to the problem of salt crystallization from solution and explicit results are given for model aqueous alkali-halide systems. Both direct- and Fourier-space methods of calculation are considered and it is found that only the direct (i.e., r space) method converges sufficiently rapidly to provide reliable results for ionic crystals at 25-degrees-C. It is shown that the density-functional method is capable of predicting crystallization, but that the solid-state parameters and, for some salts, the crystal structures obtained are in poor agreement with experiment or computer simulations. The calculated crystal/solution coexistence concentrations are found to be extremely sensitive to the short-range part of the interionic pair potentials. This is consistent with earlier observations that the activity coefficients of model aqueous alkali-halide solutions are very strongly dependent upon the short-range ion-ion interactions. Therefore, we do not believe that this sensitivity to details of the short-range interionic potentials is an artifact of theoretical approximations, but rather a real effect significantly influencing crystallization.}, keywords = {APPROXIMATION, INVARIANT EXPANSION, MEAN SPHERICAL MODEL, ORNSTEIN-ZERNIKE EQUATION, SIMULATION, SPHERES, TRANSITION, WATER}, isbn = {0021-9606}, url = {://A1991FT84700048}, author = {Ursenbach, C. P. and Patey, G. N.} } @article {7112, title = {EXCESS PARTIAL MOLAR ENTHALPIES IN THE WATER-RICH REGION OF THE ISOBUTYRIC ACID - WATER-SYSTEM}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {69}, number = {7}, year = {1991}, note = {ISI Document Delivery No.: FY816Times Cited: 8Cited Reference Count: 24}, month = {Jul}, pages = {1065-1069}, type = {Article}, abstract = {The excess partial molar enthalpies of isobutyric acid (IBA), H(m)E(IBA), and those of H2O, H(m)E(H2O), were measured in aqueous solutions of IBA. The temperature dependence of H(m)E(IBA) at the infinite dilution suggested that the structure enhancement of the solvent H2O by IBA is weaker than those by tert-butanol (TBA) or 2-butoxyethanol (BE). The concentration dependence of H(m)E(IBA), and that of the enthalpic IBA-IBA interaction, N{partial H(m)E(IBA)/partial n(B)}, shows that there are two distinct mixing schemes bounded at about x(B) = 0.03, before reaching the two phase separation. Namely, the IBA-IBA interaction is repulsive below this boundary, while above this boundary it becomes attractive leading eventually to phase separation at a higher concentration. The transition between the two schemes is associated with a peak(negative) anomally in the fourth derivative of the free energy, N2 {partial H-2(m)E(IBA)/partial n(B)2}.}, keywords = {2-BUTOXYETHANOL, CRITICAL SOLUTION TEMPERATURE, excess partial molar enthalpies, EXPONENT, INTERFACIAL-TENSION, ISOBUTYRIC ACID WATER, LIQUID WATER, MIXING SCHEME, TERT-BUTANOL MIXTURES, TRANSITION, TRANSITION IN, ULTRALOW, VICINITY, VISCOSITY}, isbn = {0008-4042}, url = {://A1991FY81600005}, author = {Siu, W. W. Y. and Wong, T. Y. H. and Chao, L. C. F. and Koga,Yoshikata} }