Isotope effects on the resonance interactions and vibrational quantum dynamics of fluoroform CHF.

We report a comparison of the analysis of the low energy spectrum of CHF and CHF from the THz (FIR) range to the ν fundamental at high resolution (δ[small nu, Greek, tilde] < 0.001 cm or otherwise Doppler limited) on the basis of FTIR spectra taken both with ordinary light sources and with the synchrotron radiation from the Swiss Light Source. Several vibrational levels are accurately determined including, in particular, the 2ν CH-bending overtone and the ν CH-stretching fundamental of CHF. Comparison of experimental results with those from accurate full dimensional vibrational calculations allows for a study of the time-dependent quantum dynamics of intramolecular vibrational redistribution (IVR) in the CH chromophore both on short time scales (fs) and longer time scales (ps) when coupling to the lower frequency modes becomes important and where the C/C isotope effects are very large.