@article {1515,
	title = {Termolecular kinetics for the Mu+CO+M recombination reaction: A unique test of quantum rate theory},
	journal = {Journal of Chemical Physics},
	volume = {125},
	number = {1},
	year = {2006},
	note = {ISI Document Delivery No.: 061CTTimes Cited: 0Cited Reference Count: 66Pan, James J. Arseneau, Donald J. Senba, Masayoshi Garner, David M. Fleming, Donald G. Xie, Tiao Bowman, Joel M.},
	month = {Jul},
	pages = {13},
	type = {Article},
	abstract = {The room-temperature termolecular rate constants, k(0), for the Mu+CO+M reversible arrow MuCO+M (M=He, N-2, Ar) recombination reaction have been measured by the mu SR technique, and are reported for moderator gas pressures of up to similar to 200 bar (densities less than or similar to 0.4x10(22) molec cm(-3)). The experimental relaxation rates reveal an unusual signature, in being dominated by the electron spin-rotation interaction in the MuCO center dot radical that is formed in the addition step. In N-2 moderator, k(0)=1.2 +/- 0.1x10(-34) cm(6) s(-1), only about 30\% higher than found in Ar or He. The experimental results are compared with theoretical calculations carried out on the Werner-Keller-Schinke (WKS) surface [Keller , J. Chem. Phys. 105, 4983 (1996)], within the framework of the isolated resonance model (IRM). The positions and lifetimes of resonance states are obtained by solving the complex Hamiltonian for the nonrotating MuCO system, using an L-2 method, with an absorbing potential in the asymptotic region. Accurate values of the vibrational bound and resonance states of MuCO reveal unprecedented isotope effects in comparisons with HCO, due to the remarkable effect of replacing H by the very light Mu atom (m(Mu)approximate to 1/9m(H)). Due to its pronounced zero-point energy shift, there are only two (J=0) bound states in MuCO. Contributions from nonzero J states to the termolecular rate constants are evaluated through the J-shifting approximation, with rotational constants evaluated at the potential minimum. The value of the important A constant (181 cm(-1)) used in this approximation was supported by accurate J=K=1 calculations, from which A=180 cm(-1) was obtained by numerical evaluation. The calculations presented here, with a "weak collision factor" beta(c)=0.001, indicative of the very sparse density of MuCO states, give a very good account of both the magnitude and pressure dependence of the experimental rates, but only when the fact that the two initially bound (J=0) states become resonances for J > 0 is taken into account. This is the first time in IRM calculations of atom-molecule recombination reactions where J not equal 0 states have proven to be so important, thus providing a truly unique test of quantum rate theory. (c) 2006 American Institute of Physics.},
	keywords = {ADDITION-REACTIONS, DISSOCIATION DYNAMICS, FIELD-DEPENDENCE, GAS-PHASE, RATE-CONSTANT, RESOLUTION SPECTROSCOPIC DATA, RESONANCE ENERGIES, SPIN RELAXATION, thermal, THERMODYNAMIC PROPERTIES, UNIMOLECULAR, VIBRATIONALLY EXCITED DCO((X)OVER-TILDE(2)A{\textquoteright})},
	isbn = {0021-9606},
	url = {<Go to ISI>://000238849500019},
	author = {Pan, J. J. and Arseneau, D. J. and Senba, M. and Garner, D. M. and Fleming, Donald G. and Xie, T. and Bowman, J. M.}
}
@article {375,
	title = {Hyperfine and host-guest interactions of the Mu-cyclohexadienyl radical in NaY zeolite},
	journal = {Journal of Physical Chemistry B},
	volume = {106},
	number = {25},
	year = {2002},
	note = {ISI Document Delivery No.: 565EUTimes Cited: 8Cited Reference Count: 88},
	month = {Jun},
	pages = {6395-6407},
	type = {Article},
	abstract = {The adsorption and dynamical behavior of the muonated cyclohexadienyl radical (C(6)H(6)Mu) in NaY zeolite, formed by muonium (Mu) addition on adsorbed benzene. was investigated by the muon spin resonance (muSR) technique, primarily at loadings of 2-3 C6H6 molecules per supercage of NaY. The dynamics of this radical are expected to be the same as its isotopic analogue, C6H7, for which there are no similar data available. Both TF-muSR and ALC-muSR spectra were recorded, with the most detailed information provided by the positions and line widths of the avoided level crossing resonances. In concert with H-2 NMR, neutron diffraction and molecular dynamics studies of the parent benzene molecule, as well as current theoretical calculations, the dominant adsorption site for the C(6)H(6)Mu radical is believed to be the S-II Na cation, within a supercage, which gives rise to three observed ALC lines, corresponding to two different orientations for the muon (proton) of the CHMu methylene group: pointing toward (endo) and away (exo) from the Na cation. The cation interaction gives rise to unprecedentedly large (approximate to20\%) shifts in hyperfine coupling constants, indicative of a strong bond formed with the T electrons of the C(6)H(6)Mu radical. An additional but weaker resonance line is also seen, which is interpreted as being due to adsorption at the window sites between supercages. The ALC lines associated with the CH,,Mu radical bound to both the Na cation and window sites are all broad, approximate to1 kG, change little with temperature and exhibit mainly static line shapes over the whole temperature range studied, from 3 to 322 K. This indicates a much stronger host-guest interaction for C(6)H(6)Mu, particularly with the Na cation. than is known for benzene, to the extent that this site acts as an effective trap for the free radical, over the critical muSR time scale of 50 ns.},
	keywords = {AROMATIC-MOLECULES, ELASTIC NEUTRON-SCATTERING, GAS-PHASE, H-2 NMR, MAGNETIC-RESONANCE, MOLECULAR-DYNAMICS, RAY-POWDER DIFFRACTION, REORIENTATIONAL DYNAMICS, SODIUM-Y ZEOLITE, SPIN RELAXATION},
	isbn = {1520-6106},
	url = {<Go to ISI>://000176356700007},
	author = {Fleming, Donald G. and Shelley, M. Y. and Arseneau, D. J. and Senba, M. and Pan, J. J. and Roduner, E.}
}
@article {4096,
	title = {Reaction kinetics of muonium with N2O in the gas phase},
	journal = {Journal of Physical Chemistry A},
	volume = {101},
	number = {45},
	year = {1997},
	note = {ISI Document Delivery No.: YF251Times Cited: 6Cited Reference Count: 64},
	month = {Nov},
	pages = {8470-8479},
	type = {Article},
	abstract = {The thermal reaction Mu + N2O has been studied by the muon spin rotation (mu SR) technique at temperatures from 303 to 593 K and pressures up to 60 atm. The overall reaction rate coefficient depends on the N2O pressure quadratically in pure N2O and is proportional to both the N2O partial pressure and the total pressure in mixtures, confirming the theoretical prediction of Diau and Lin that the analogous H atom reaction proceeds through two channels in this temperature range, forming different products, MuN(2)O and MuO + N-2. The measured total rate coefficients are much larger than those reported by Marshall et al. for H(D) + N2O, indicating a dramatic kinetic isotope effect, which is mainly due to the enhanced quantum tunneling of the ultralight Mu atom. Even at room temperature (and low pressure), k(Mu)/k(H) approximate to 120, the largest yet seen in comparisons of gas-phase Mu and H reactivity at such relatively high temperatures. The addition reaction forming MuN(2)O (and by implication, HN2O) contributes significantly to the total reaction rate at higher pressures but with the thermal rate coefficient remaining in the termolecular regime even at the highest pressures measured.},
	keywords = {ADDITION-REACTIONS, CHARGE-EXCHANGE, CHEMICAL-REACTION, H-ATOMS, HIGH-TEMPERATURE PHOTOCHEMISTRY, HYDROGEN-ATOMS, radicals, RATE CONSTANTS, SHOCK-TUBE, SPIN RELAXATION},
	isbn = {1089-5639},
	url = {<Go to ISI>://A1997YF25100014},
	author = {Pan, J. J. and Arseneau, D. J. and Senba, M. and Shelly, M. and Fleming, Donald G.}
}
@article {3940,
	title = {Why ALC mu SR is superior for gas-phase radical spectroscopy},
	journal = {Hyperfine Interactions},
	volume = {106},
	number = {1-4},
	year = {1997},
	note = {ISI Document Delivery No.: XB055Times Cited: 9Cited Reference Count: 147th International Conference on Muon Spin Rotation, Relaxation, ResonanceAPR 15-19, 1996NIKKO, JAPANUniv Tokyo, Meson Sci Lab, Inst Phys \& Chem Res, Muon Sci Lab},
	pages = {137-142},
	type = {Proceedings Paper},
	abstract = {ALC mu SR spectra of the muonated ethyl and cyclohexadienyl radicals in the gas phase are reported. They have surprisingly narrow lines for a magnetic resonance type technique under conditions near ambient temperature and near 1 atmosphere pressure. The main reason for this behaviour is the dramatic reduction of electron spin relaxation in high magnetic fields.},
	keywords = {HYPERFINE CONSTANTS, ORGANIC FREE-RADICALS, SPECTRA, SPIN RELAXATION},
	isbn = {0304-3843},
	url = {<Go to ISI>://A1997XB05500019},
	author = {Dilger, H. and Roduner, E. and Stolmar, M. and Reid, I. D. and Fleming, Donald G. and Arseneau, D. J. and Pan, J. J. and Senba, M. and Shelley, M.}
}
