15min:

CARINE MANCA TANNER, SIEGHARD ALBERT AND MARTIN QUACK, Physical Chemistry, ETH Zurich, Switzerland.

In our group we pursue two experimental approaches to investigate Intramolecular Vibrational Redistribution (IVR)^a: this process can be studied by time-resolved femtosecond pump-probe experiments, or the corresponding time-dependent quantum dynamics can be obtained from stationary spectra in the IR at high frequency resolution by a time-dependent analysis using the underlying Hamiltonian and time evolution operator. Recent work in our group\footnoteV. Krylov, M. Nikitchenko, M. Quack, and G. Seyfang, Proc. SPIEE \textbf5337, 178 (2004);V. Krylov, A. Kushnarenko, E. Miloglyadov, M. Quack, and G. Seyfang, Proc. SPIEE \textbf6460, 64601D-1 (2007). has shown that CH₃I and its deuterated isotopomers have different IVR-times, revealing different intramolecular coupling schemes for the initially excited vibrational levels. The present work is part of a larger effort to understand IVR in these molecules on the basis of high resolution spectra in the 500-12000~cm^-1 region. In previous work we have analyzed the strong Fermi-resonance coupling between the CH-stretching and bending modes in CHD₂I at modest resolution, demonstrating very fast redistribution times on the order of 100~fs. We refer to this recent paper for the past literature on the topic. Here we present detailed rovibrational analysis of ₁ and several other fundamentals of CHD₂I recorded with our high resolution FTIR spectrometer Bruker ZP2001 with resolutions up to 0.0008~cm^-1. We discuss our new results in relation to our recent work on the overtone spectra and dynamics and to the femtosecond pump-probe results.