@article {1551,
	title = {Slowing-down times and stopping powers for similar to 2-MeV mu(+) in low-pressure gases},
	journal = {Physical Review A},
	volume = {74},
	number = {4},
	year = {2006},
	note = {ISI Document Delivery No.: 101EXTimes Cited: 3Cited Reference Count: 86Senba, Masayoshi Arseneau, Donald J. Pan, James J. Fleming, Donald G.},
	month = {Oct},
	pages = {17},
	type = {Article},
	abstract = {The times taken by positive muons (mu(+)) to slow down from initial energies in the range similar to 3 to 1 MeV, to the energy of the last muonium formation, approximate to 10 eV, at the end of cyclic charge exchange, have been measured in the pure gases H-2, N-2, Ar, and in the gas mixtures Ar-He, Ar-Ne, Ar-CF4, H-2-He, and H-2-SF6, by the muon spin rotation (mu SR) technique. At 1 atm pressure, these slowing-down times, tau(SD), in Ar and N-2, vary from similar to 14 ns at the highest initial energies of 2.8 MeV to 6.5 ns at 1.6 MeV, with much longer times, similar to 34 ns, seen at this energy in H-2. Similar variations are seen in the gas mixtures, depending also on the total charge and nature of the mixture and consistent with well-established (Bragg) additivity rules. The times tau(SD) could also be used to determine the stopping powers, dE/dx, of the positive muon in N-2, Ar, and H-2, at kinetic energies near 2 MeV. The results demonstrate that the mu(+) and proton have the same stopping power at the same projectile velocity, as expected from the historic Bethe-Bloch formula, but not previously shown experimentally to our knowledge for the muon in gases at these energies. The energy of the first neutralization collision forming muonium (hydrogen), which initiates a series of charge-exchanging collisions, is also calculated for He, Ne, and Ar. The formalism necessary to describe the stopping power and moderation times, for either muon or proton, in three energy regimes-the Bethe-Bloch, cyclic charge exchange, and thermalization regimes-is developed and discussed in comparison with the experimental measurements reported here, and elsewhere. The slowing-down times through the first two regimes are controlled by the relevant ionization and charge-exchange cross sections, whereas the final thermalization regime is most sensitive to the forwardness of the elastic scattering cross sections. In this regime the slowing-down times (to kT) at nominal pressures are expected to be less than or similar to 100 ns.},
	keywords = {ALPHA-PARTICLES, BINARY THEORY, CHARGE-EXCHANGE, COMPETING PROCESSES, CROSS-SECTIONS, ELECTRON-SPIN EXCHANGE, HYDROGEN-ATOMS, MUONIUM-FORMATION, POSITIVE MUONS, RADIATION-CHEMISTRY},
	isbn = {1050-2947},
	url = {<Go to ISI>://000241723100090},
	author = {Senba, M. and Arseneau, D. J. and Pan, J. J. and Fleming, Donald G.}
}
@article {1141,
	title = {Muon implantation in inert gases studied by radio frequency spectroscopy},
	journal = {Journal of Physics B-Atomic Molecular and Optical Physics},
	volume = {38},
	number = {1},
	year = {2005},
	note = {ISI Document Delivery No.: 898AETimes Cited: 1Cited Reference Count: 51},
	month = {Jan},
	pages = {119-134},
	type = {Article},
	abstract = {Diamagnetic and muonium (Mu) fractions formed in low-pressure inert gases, by energetic muon implantation, have been studied using the technique of time-delayed radio frequency muon spin resonance (RF-muSR). Results obtained establish the validity of the long-held view that formation of these species is due only to prompt processes, and in turn confirms that the diamagnetic environment is due to a muon molecular ion, MMu(+), and not a bare mu(+). In addition, polarization fractions for the diamagnetic and Mu environments have been determined at different pressures, thereby complementing earlier data, and demonstrating that the RF-muSR technique provides polarization fractions in good accord with those obtained using conventional transverse-field muon spin resonance measurements.},
	keywords = {ADDITION-REACTIONS, CHARGE-EXCHANGE COLLISIONS, COMPETING PROCESSES, ELECTRON-SPIN EXCHANGE, MOLECULAR-IONS, NOBLE-GASES, POSITIVE MUONS, RESONANCE, SLOWING-DOWN, SUPERCRITICAL WATER},
	isbn = {0953-4075},
	url = {<Go to ISI>://000227047200016},
	author = {Johnson, C. and Cottrell, S. P. and Ghandi, K. and Fleming, Donald G.}
}
@article {4897,
	title = {Measurements of Mu+NO termolecular kinetics up to 520 bar: isotope effects and the Troe theory},
	journal = {Physical Chemistry Chemical Physics},
	volume = {2},
	number = {4},
	year = {2000},
	note = {ISI Document Delivery No.: 281JDTimes Cited: 3Cited Reference Count: 58},
	pages = {621-629},
	type = {Article},
	abstract = {The recombination reaction Mu + NO + MMuNO + M (M = He, N-2, CH4) has been studied by the muon spin relaxation/rotation (mu SR) technique up to 520 bar at room temperature. The reaction remains in the low pressure regime throughout. The measured termolecular addition rate constant in N-2, 8.8 +/- 0.3 x 10(-33) cm(6) s(-1), is essentially the same as that found in our earlier study at pressures below 60 bar [J. J. Pan et al., J. Phys. Chem., 1995, 99, 17160]. It is somewhat smaller in He, 7.7 +/- 1.0 x 10(-33), but larger in CH4, 12.8 +/- 2.0 x 10(-33). The Mu + NO reaction is about five times slower than the corresponding H + NO reaction. The strong collision limits of the rate constants for three H-isotopes (Mu, H, D) reacting with NO have been estimated with Troe{\textquoteright}s formalism for unimolecular dissociation in the low pressure regime, based on the ab initio potential energy surface of Guadagnini et al. [J. Chem. Phys., 1995, 102, 774]. The Troe calculations give less than satisfactory agreement with experiment with the corresponding weak collision factor, beta(c), higher than expected by a factor of similar to 2 for H + NO. The calculated kinetic isotope effect in the strong collision limit for Mu/H is weaker than the measured effect by a factor of two giving an apparent large isotope effect in this factor, beta(c)(Mu) approximate to 1/2,beta(o)(H), possibly due to mode specific collisional stabilization.},
	keywords = {COLLISIONAL ENERGY-TRANSFER, DISSOCIATION, ELECTRON-SPIN EXCHANGE, GAS-PHASE, HIGH-PRESSURES, HNO, muonium, RATE CONSTANTS, relaxation, THERMAL UNIMOLECULAR REACTIONS},
	isbn = {1463-9076},
	url = {<Go to ISI>://000085154400025},
	author = {Pan, J. J. and Arseneau, D. J. and Senba, M. and Fleming, Donald G. and Himmer, U. and Suzuki, Y.}
}
@article {4723,
	title = {The rate constant for Mu+O-2 addition in competition with rapid spin exchange},
	journal = {Physica B-Condensed Matter},
	volume = {289},
	year = {2000},
	note = {ISI Document Delivery No.: 330GBTimes Cited: 3Cited Reference Count: 158th International Conference on Muon Spin Rotation, Relaxation and ResonanceAUG 30-SEP 03, 1999LES DIABLERETS, SWITZERLANDEuropean Phys Soc, Paul Scherrer Inst, Eidgenoss Tech Hochschule, Univ Zurich, European Sci Fdn, Swiss Natl Sci Fdn, Neue Aargauer Bank, Sauerstoffwerk Lenzburg AG, Hamamatsu Photon, EG \& G Berthold GmbH \& Co KG, Prophysik AG, Kroger \& Co, Wenger SA, Alcatel Hochvakuum Tech GmbH, Sunrise AG, Dramer AG, Automobil \& Motoren AG},
	month = {Aug},
	pages = {503-506},
	type = {Proceedings Paper},
	abstract = {The rate of the addition reaction H + O-2 {\textendash}> HO2, is measured at high O-2 concentrations (up to 40 bar of O-2 at room temperature) through its competition with rapid spin exchange, to give k(ch)(0) = 8.7 +/- 0.8 x 10(-3)3 cm(6)s(-1) ch (C) 2000 Published by Elsevier Science B.V. All rights reserved.},
	keywords = {ELECTRON-SPIN EXCHANGE, GAS-PHASE, muonium, muonium oxygen recombination kinetics spin exchange, radicals, relaxation},
	isbn = {0921-4526},
	url = {<Go to ISI>://000087953500130},
	author = {Arseneau, D. J. and Senba, M. and Pan, J. J. and Fleming, Donald G.}
}
@article {3473,
	title = {MU+NO - KINETIC ISOTOPE EFFECTS IN UNIMOLECULAR DISSOCIATION},
	journal = {Journal of Physical Chemistry},
	volume = {99},
	number = {47},
	year = {1995},
	note = {ISI Document Delivery No.: TF811Times Cited: 10Cited Reference Count: 80},
	month = {Nov},
	pages = {17160-17168},
	type = {Article},
	abstract = {The thermal addition reaction Mu + NO + M reversible arrow MuNO* + M has been studied by a longitudinal magnetic field muon spin relaxation (mu SR) technique, at room temperature, in the presence of up to 60 atm of N-2 as inert moderator. The pressure dependence of the effective rate constant for Mu addition (k(eff)) demonstrates that the system remains well in the low-pressure regime in this pressure range. The termolecular rate constant, k(0)(Mu) = (8.76 +/- 0.46) x 10(-33) cm(6) molecule(-2) s(-1), is about 5 times smaller than that reported for the corresponding H-atom reaction (Tsang, W.; Herron, J. T. J. Phys. Chem. Ref. Data 1991, 20, 609), the largest isotope effect of its kind yet reported for reactions of this nature and most likely due to the increased rate of MuNO* dissociation resulting from the much lighter mass of the Mu atom (m(Mu)/m(H) similar to 1/9). This result should provide an important test of theoretical calculations for dissociating molecules involving few degrees of freedom. Quantum tunneling, normally facile for the much lighter Mu atom, is unlikely to play a major role in establishing the isotope effect seen in k(0). In the present instance, the mu SR technique relies on measuring the relaxation rate for the chemical process of addition (lambda(c)) in competition with that for spin exchange (lambda(se)), with the NO unpaired electron. The pressure-independent average value for the spin exchange rate constant found, k(se) = (3.00 +/- 0.12) x 10(-10) cm(3) molecule(-1) s(-1), is in good agreement with previous values obtained by transverse field mu SR (Fleming, D. G., et al. J. Chem. Phys. 1980, 73, 2751).},
	keywords = {CHANNEL MODEL-CALCULATIONS, CHARACTERIZATION, ELECTRON-SPIN EXCHANGE, H+CH3->CH4 RECOMBINATION, INTERPOLATED, MICROCANONICAL VARIATIONAL THEORY, PARTITION-FUNCTION, POTENTIAL-ENERGY, PRESSURE-DEPENDENCE, RADICAL RECOMBINATION, RATE CONSTANTS, SURFACES, THEORETICAL},
	isbn = {0022-3654},
	url = {<Go to ISI>://A1995TF81100019},
	author = {Pan, J. J. and Senba, M. and Arseneau, D. J. and Gonzalez, A. C. and Kempton, J. R. and Fleming, Donald G.}
}
