Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Dependence of Multiphonon Transitions on Interaction Strength and Temperature

Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia [Pg.151]

A non-perturbative theory of the multiphonon relaxation of a localized vibrational mode, caused by a high-order anharmonic interaction with the nearest atoms of the crystal lattice, is proposed. It relates the rate of the process to the time-dependent non-stationary displacement correlation function of atoms. A non-linear integral equation for this function is derived and solved numerically for 3- and 4-phonon processes. We have found that the rate exhibits a critical behavior it sharply increases near a specific (critical) value(s) of the interaction. [Pg.151]

The temperature dependence of non-radiative transitions, caused by linear diagonal and quadratic non-diagonal vibronic interactions, is also investigated on the basis of the non-perturbative quantum theory. It was found that the usual increase of the transition rate with temperature does not hold near some critical values of the non-diagonal interaction and temperature. At these critical values the rate is high (comparable to the mean phonon frequency) and its temperature dependence has a maximum. The results may be important for understanding the mechanisms of catalysis in chemical reactions. [Pg.151]

Multiphonon transitions in molecular systems and in solids are usually described by the perturbation theory [1-12]. This theory works only if the interaction causing the process is weak. However, very often this interaction is rather strong. To explain the results of measurements in such a case, a non-perturbative theory is needed. [Pg.151]

ADVANCES IN QUANTUM CHEMISTRY, VOLUME 44 ISSN 0065-3276 DOI 10.1016/S0065-3276(03)44010-0 [Pg.151]


Critical Dependence of Multiphonon Transitions on Interaction Strength and Temperature... [Pg.151]




SEARCH



Dependence on temperature

Dependence on temperature and

Interaction strength

Interactions dependence

Multiphonon

Multiphonon transitions

Strength and temperature

Strength temperature dependence

Temperature and interactions

Temperature dependence of interaction

Temperature dependence of strength

Temperature dependence transition

Temperature of transition

Temperature on strength

Temperature strength

Transition interaction

Transition strength

© 2024 chempedia.info