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Conformational Changes in Cryogenic Matrices
Published in Leonid Khriachtchev, Physics and Chemistry at Low Temperatures, 2019
Rui Fausto, Leonid Khriachtchev, Peter Hamm
The idea of IR-induced conformational change is the following. The initial conformer is transferred by IR light to a vibrationally excited state; however, in contrast to the previous section, the molecule stays in the electronic ground state. The vibrational excitation is followed by intramolecular vibrational energy redistribution (IVR), the excited molecule can relax with some probability to various possible conformers, and the conformational change may occur. In order to promote conformational changes, the excitation energy should be high enough, at least not much smaller than the reaction barrier. Many studies of conformational changes have been done using broadband light sources in low-temperature matrices.40–51 However, in this section we concentrate on the processes promoted by narrowband IR light. In this situation, selective and efficient excitation of a chosen conformer is possible, which allows detailed studies of light-induced conformational changes.52
Vibrational control of molecular electron transfer reactions
Published in Molecular Physics, 2019
Stephanie Valianti, Spiros S. Skourtis
These equations indicate that the effect of IR driving on the ET rate is transient and it is expected to vanish sometime after the application of the IR pulse and on a timescale that is related to the intramolecular vibrational energy redistribution (IVR) times of the molecule-solvent ET system (denoted ). Thus, setting as the time right after the application of the IR pulse, we expect the IR-perturbed mode probability distributions to decay to the equilibrium distributions for , i.e. in Equation (19) (and in Equation 20). A large IR-induced effect on the non-adiabatic ET rate would require that, for the time period between the application of the IR pulse and , or .