@article {2664, title = {Gas-Phase H/D Exchange and Collision Cross Sections of Hemoglobin Monomers, Dimers, and Tetramers}, journal = {Journal of the American Society for Mass Spectrometry}, volume = {20}, number = {3}, year = {2009}, note = {ISI Document Delivery No.: 417NGTimes Cited: 1Cited Reference Count: 71Wright, P. John Douglas, D. J.}, month = {Mar}, pages = {484-495}, type = {Article}, abstract = {The conformations of gas-phase ions of hemoglobin, and its dimer and monomer subunits have been studied with H/D exchange and cross section measurements. During the H/D exchange measurements, tetramers undergo slow dissociation to dimers, and dimers to monomers, but this did not prevent drawing conclusions about the relative exchange levels of monomers, dimers, and tetramers. Assembly of the monomers into tetramers, hexamers, and octamers causes the monomers to exchange a greater fraction of their hydrogens. Dimer ions, however, exchange a lower fraction of their hydrogens than monomers or tetramers. Solvation of tetramers affects the exchange kinetics. Solvation molecules do not appear to exchange, and solvation lowers the overall exchange level of the tetramers. Cross section measurements show that monomer ions in low charge states, and tetramer ions have compact structures, comparable in size to the native conformations in solution. Dimers have remarkably compact structures, considerably smaller than the native conformation in solution and smaller than might be expected from the monomer or tetramer cross sections. This is consistent with the relatively low level of exchange of the dimers. (J Am Soc Mass Spectrom 2009, 20, 484-495) (C) 2009 Published by Elsevier Inc. on behalf of American Society for Mass Spectrometry}, keywords = {ACID-INDUCED DENATURATION, CYTOCHROME-C IONS, DIFFERENT SOLUTION CONFORMATIONS, ELECTROSPRAY MASS-SPECTROMETRY, EXCHANGE, GLOBIN CHAINS, HYDROGEN/DEUTERIUM, ION-TRAP, MYOGLOBIN IONS, noncovalent protein complexes, OF-FLIGHT SYSTEM, QUADRUPOLE}, isbn = {1044-0305}, url = {://000264082200018}, author = {Wright, P. J. and Douglas, D. J.} } @article {2402, title = {LINEAR QUADRUPOLES IN MASS SPECTROMETRY}, journal = {Mass Spectrometry Reviews}, volume = {28}, number = {6}, year = {2009}, note = {ISI Document Delivery No.: 515CWTimes Cited: 5Cited Reference Count: 145Douglas, D. J.}, month = {Nov-Dec}, pages = {937-960}, type = {Review}, abstract = {The use of linear quadrupoles in mass spectrometry as mass filters and ion guides is reviewed. Following a tutorial review of the principles of mass filter operation, methods of mass analysis are reviewed. Discussed are extensions of quadrupole mass filters to higher masses, scanning with frequency sweeps of the quadrupole waveform, operation in higher stability regions, and operation with rectangular or other periodic waveforms. Two relatively new methods of mass analysis the use of "islands of stability" and "mass selective axial ejection" are then reviewed. The optimal electrode geometry for a quadrupole mass filter constructed with round rods is discussed. The use of collisional cooling in quadrupole ion guides is discussed along with ion guides that have axial fields. Finally, mass analysis with quadrupoles that have large distortions to the geometry and fields is discussed. An Appendix gives a brief tutorial review of definitions of electrical potentials and fields, as well as the units used in this article. (C) 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:937-960, 2009}, keywords = {2ND STABILITY REGION, axial fields, AXIAL-FIELD, CHARGED-PARTICLE, COLLISION-INDUCED DISSOCIATION, distorted fields, FRINGING FIELDS, ion guide, ION OPTICAL-PROPERTIES, linear, mass filter, mass scans, multipoles, OCTOPOLE FIELDS, QUADRUPOLE, quadrupole excitation, RADIO-FREQUENCY, RESOLUTION, SEPARATION MODE, STABILITY, TRAJECTORIES, VOLTAGE COMPONENT}, isbn = {0277-7037}, url = {://000271445200005}, author = {Douglas, D. J.} } @article {1097, title = {Linear ion traps in mass spectrometry}, journal = {Mass Spectrometry Reviews}, volume = {24}, number = {1}, year = {2005}, note = {ISI Document Delivery No.: 888OJTimes Cited: 73Cited Reference Count: 145}, month = {Jan-Feb}, pages = {1-29}, type = {Review}, abstract = {Linear ion traps are finding new applications in many areas of mass spectrometry. In a linear ion trap, ions are confined radially by a two-dimensional (2D) radio frequency (RF) field, and axially by stopping potentials applied to end electrodes. This review focuses on linear ion trap instrumentation. Potentials and ion motion in linear multipole fields and methods of ion trapping, cooling, excitation, and isolation are described. This is followed by a description of various mass discrimination effects that have been reported with linear ion traps. Linear ion traps combined in various ways with three-dimensional (3D) traps, time-of-flight (TOF) mass analyzers, and Fourier transform ion cyclotron resonance mass spectrometers are then given. Linear ion traps can be used as stand alone mass analyzers, and their use for mass analysis by Fourier transforming image currents, by mass selective radial ejection, and by mass selective axial ejection are reviewed. (C) 2004 Wiley Periodicals, Inc.}, keywords = {analysis, CYCLOTRON-RESONANCE, ELECTROSPRAY-IONIZATION, EXCITATION, EXTERNAL ACCUMULATION, FRINGING FIELDS, INVERSE FOURIER-TRANSFORM, ion traps, linear multipoles, mass, MOLECULE REACTION, OCTOPOLE FIELDS, OF-FLIGHT, QUADRUPOLE, RADIOFREQUENCY, RESONANCE, space charge, STORAGE ASSISTED DISSOCIATION, SYSTEM}, isbn = {0277-7037}, url = {://000226383800001}, author = {Douglas, D. J. and Frank, A. J. and Mao, D. M.} } @article {826, title = {Microwave spectra, nuclear field shift effects, geometries and hyperfine constants of bismuth mononitride, BiN, and bismuth monophosphide, BiP}, journal = {Journal of Molecular Structure}, volume = {695}, year = {2004}, note = {ISI Document Delivery No.: 827SVTimes Cited: 11Cited Reference Count: 66Sp. Iss. SI}, month = {Jun}, pages = {13-22}, type = {Article}, abstract = {The diatomic molecules BiN and BiP have been prepared using a laser ablation technique and studied by Fourier transform microwave spectroscopy in the frequency range 7-22 GHz. For BiN, only the J = 1-0 transition fell within this range. Transitions for the ground and first excited vibrational states have been observed for both (BiN)-N-14 and (BiN)-N-15. For BiP, which has only one isotopomer, the transitions J{\textquoteright}-J" = 1-0. 2-1 and 3-2 have been observed, but only for the ground vibrational state. Hyperfine structure has been observed for both nuclei in both molecules the Bi-209 nuclear quadrupole coupling constants show that the electronic structures are similar for the two molecules. Improved bond lengths have been obtained for both molecules. Density functional methods have been used to estimate the electron density at the bismuth nucleus in each molecule and hence allow an estimate of the uncertainty due to field shift effects in the experimentally derived bond lengths. (C) 2003 Elsevier B.V. All rights reserved.}, keywords = {BII, BiN, BiP, BORN-OPPENHEIMER APPROXIMATION, Born-Oppenheimer breakdown, DIATOMIC-MOLECULES, DUNHAM COEFFICIENTS, FOURIER-TRANSFORM SPECTROSCOPY, GROUND-STATE, HIGH-RESOLUTION, HYPERFINE, IODIDE, ISOTOPE DEPENDENCE, microwave spectra, MOMENTS, nuclear field shift effects, QUADRUPOLE, ROTATIONAL SPECTRUM, STRUCTURE}, isbn = {0022-2860}, url = {://000221922000003}, author = {Cooke, S. A. and Michaud, J. M. and Gerry, M. C. L.} } @article {4222, title = {A new linear ion trap time-of-flight system with tandem mass spectrometry capabilities}, journal = {Rapid Communications in Mass Spectrometry}, volume = {12}, number = {20}, year = {1998}, note = {ISI Document Delivery No.: 130DBTimes Cited: 92Cited Reference Count: 64}, pages = {1463-1474}, type = {Article}, abstract = {A new hybrid linear ion trap time-of-flight mass spectrometer has been constructed and the first results for tandem-in-time MS/MS in a 2-dimensional Paul trap are presented. The instrument consists of an electrospray ionization source and two radio frequency (RF) only quadrupoles operating at a pressure of 7 mTorr N-2 which are coupled orthogonally to a linear TOFMS. Ions are trapped in an RF-only quadrupole through the application of timed stopping potentials on the entrance and exit apertures. Through the coupling of an auxiliary waveform generator on one pair of the ion trap rods a small dipolar excitation voltage is superimposed on the quadrupolar electric field. This voltage is used for precursor isolation via broadband excitation and collision induced dissociation through mass selective resonant excitation. Instrumental performance and choice of operating parameters are demonstrated by recording fragment spectra for +3 ions of renin substrate and fl ions of reserpine. TOFMS mass resolution (m/Delta m)(FWHM) is as high as 740 at m/z = 609. Fragmentation efficiency is greater than 50\% and excitation mass resolution is 60-75. (C) 1998 John Wiley \& Sons, Ltd.}, keywords = {DECOMPOSITION, EJECTION, ELECTROSPRAY-IONIZATION, FREQUENCY STANDARD APPLICATIONS, MOLECULE REACTION, PARAMETERS, PERFORMANCE, PROTEINS, QUADRUPOLE, RESONANCE, SPECTROSCOPY}, isbn = {0951-4198}, url = {://000076503200007}, author = {Campbell, J. M. and Collings, B. A. and Douglas, D. J.} } @article {4227, title = {Stability of a highly charged noncovalent complex in the gas phase: Holomyoglobin}, journal = {Rapid Communications in Mass Spectrometry}, volume = {12}, number = {15}, year = {1998}, note = {ISI Document Delivery No.: 105GATimes Cited: 33Cited Reference Count: 56}, pages = {1003-1010}, type = {Article}, abstract = {Gas phase holomyoglobin (hMb) ions in charge states +7 to +21 were formed by electrospray ionization in combination with a continuous-flow mixing apparatus. Collision cross section measurements show that the highly charged ions are somewhat unfolded in comparison to low charge states but still retain a considerable degree of folding. A new collision model is presented which calculates the relative energies transferred to complexes in tandem mass spectrometry. Tandem mass spectrometry and ion trapping experiments both show that the energies required to dissociate heme from the highly charged heme-protein complexes in the gas phase are similar to those of low charge states, previously shown in literature ion cyclotron resonance experiments to be 0.7-1.0 eV, These energies are comparable to those of the heme binding energy in solution. The results suggest that even for the highly charged hMb ions which have unfolded somewhat, the heme-protein interactions remain relatively unperturbed. (C) 1998 John Wiley \& Sons, Ltd.}, keywords = {CONFORMATION, CYTOCHROME-C, ELECTROSPRAY-IONIZATION, ion-molecule, IONIZATION MASS-SPECTROMETRY, METMYOGLOBIN, MYOGLOBIN, PROTEIN IONS, PROTON-TRANSFER REACTIVITY, QUADRUPOLE, reaction}, isbn = {0951-4198}, url = {://000075063300003}, author = {Chen, Y. L. and Campbell, J. M. and Collings, B. A. and Konermann, L. and Douglas, D. J.} } @article {3571, title = {PULSED-BEAM MICROWAVE FOURIER-TRANSFORM MEASUREMENTS ON ISOTOPICALLY SUBSTITUTED VAN-DER-WAALS DIMER NE-OCS}, journal = {Journal of Molecular Spectroscopy}, volume = {169}, number = {2}, year = {1995}, note = {ISI Document Delivery No.: QD984Times Cited: 12Cited Reference Count: 23}, month = {Feb}, pages = {542-554}, type = {Article}, abstract = {Pure rotational spectra of seven isotopomers of Ne-OCS (Ne-OCS, Ne-22-OCS, Ne-21-OCS, Ne-(OCS)-O-18, Ne-(OCS)-C-13, Ne-(OCS)-S-34, and Ne-(OCS)-S-33) have been investigated using a pulsed jet cavity microwave Fourier transform spectrometer. Rotational and centrifugal distortion constants have been determined for all species, as well as the nuclear quadrupole coupling constants of S-33 and Ne-21 in Ne-(OCS)-S-33 and Ne-21-OCS, respectively. Harmonic force field analyses have been performed which account for the Variations in the distortion constants between the isotopomers. Effective and ground state average structures have been obtained and are discussed in light of the nuclear quadrupole coupling constants and of dipole moment measurements. The determined coupling constants have provided a means of comparing the effects of perturbation of the electronic structures of both constituents upon complexation. An electrostatic model has been applied to calculate the Ne-21 coupling constants and a possible source of their disagreement with experiment is discussed. (C) 1995 Academic Press, Inc.}, keywords = {AR, COMPLEXES, DIPOLE-MOMENTS, FORCE-FIELD, INFRARED-ABSORPTION, KR, KR-83, QUADRUPOLE, ROTATIONAL SPECTRUM, SPECTROSCOPY}, isbn = {0022-2852}, url = {://A1995QD98400022}, author = {Xu, Y. J. and Gerry, M. C. L.} } @article {2818, title = {HYPERFINE STRUCTURES IN THE ROTATIONAL SPECTRA OF THIONYLIMIDE, HNSO, AND THIONYLIMIDE-D, DNSO}, journal = {Journal of Molecular Spectroscopy}, volume = {158}, number = {1}, year = {1993}, note = {ISI Document Delivery No.: KQ338Times Cited: 8Cited Reference Count: 14}, month = {Mar}, pages = {62-68}, type = {Article}, keywords = {QUADRUPOLE}, isbn = {0022-2852}, url = {://A1993KQ33800007}, author = {Heineking, N. and Gerry, M. C. L.} } @article {7024, title = {ATOMIC MASS-SPECTROMETRY OF SOLID SAMPLES USING LASER ABLATION-ION TRAP MASS-SPECTROMETRY (LAITMS)}, journal = {Spectrochimica Acta Part B-Atomic Spectroscopy}, volume = {46}, number = {8}, year = {1991}, note = {ISI Document Delivery No.: GA509Times Cited: 27Cited Reference Count: 15}, pages = {1227-1235}, type = {Article}, abstract = {Laser ablation sampling inside the cavity of an ion trap was used to provide direct atomic mass spectrometric analysis of solid metal samples. An ion trap was designed such that a pulsed Nd:YAG laser beam was used to ablate sample pins inserted radially through the ring electrode. To demonstrate the potential of this method, atomic mass spectra were obtained for metal alloy samples.}, keywords = {CLUSTERS, QUADRUPOLE, SPECTROSCOPY}, isbn = {0584-8547}, url = {://A1991GA50900010}, author = {Gill, C. G. and Daigle, B. and Blades, M. W.} }