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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. December 2005, Volume 4, Number 12, 862-881 |
Reaction Rate Assessment of Multiphonon Relaxation
Mladen Georgiev and Alexander Gochev
Internet Electron. J. Mol. Des. 2005, 4, 862-881
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Abstract:
An investigation is made into whether the reaction-rate formalism
also applies to describing inelastic-tunneling vibronic processes
associated with the absorption and emission of phonons. We
propose that Bardeen-Christov's quantum-mechanical approach to
the transition (tunneling) probabilities originally intended for
elastic tunneling alone can formally be extended to cover inelastic
tunneling as well. Namely, we show that inelastic tunneling
through the absorption of p phonons can be regarded as an
exothermic reaction with zero-point reaction heat
Θp = -phν.
Alternatively, inelastic tunneling through the emission of p
phonons will be equivalent to an endothermic reaction with zero-point
reaction heat Θp = +phν. An analysis made indicates that the
transition (tunneling) probabilities expand into Franck-Condon
factors revealing the interconnection between reaction-rate and
multiphonon relaxation rates. Our proposal confirms to a good
approximation the traditional multiphonon fingerprint that the
relaxation rate of 1-phonon processes increases linearly with the
temperature T at low T. The combined reaction rate theory
compares favorably with numerical calculations on specific
experimental systems.
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