Description of cross-peaks induced by intermolecular vibrational energy transfer in two-dimensional infrared spectroscopy

Abstract

In the present work, the analytic description of an intermolecular vibrational energy transfer, analyzed by two-dimensional infrared spectroscopy, is established. The energy transfer process takes place between the dark combination states of low frequency modes pertaining to different molecules. The appearance of the cross-peaks results from coherent transfer between these combination states and optically active states of the molecule. Such a process has recently been observed experimentally between the nitrile groups of acetonitrile-d3 and benzonitrile molecules. This molecular system will be used as a model for the simulations of their two-dimensional infrared spectra. The dependence of the cross-peak growth, which is a signature of the intermolecular energy transfer, will be discussed in detail as a function of the molecular dynamical constants.