Isotope effects on the resonance interactions and vibrational quantum dynamics of fluoroform 12,13CHF3

Abstract

We report a comparison of the analysis of the low energy spectrum of ¹³CHF₃ and ¹²CHF₃ from the THz (FIR) range to the ν₁ fundamental at high resolution (δ < 0.001 cm⁻¹ 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 2ν₄ CH-bending overtone and the ν₁ CH-stretching fundamental of ¹³CHF₃. 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 ¹²C/¹³C isotope effects are very large.