Dynamical models in the two-dimensional infrared spectroscopy of peptides

Abstract

A brief description of the signals in multidimensional infrared spectroscopy is given with emphasis on the various types of experiments that can be done, what they measure, and their relationship to other kinds of resonant nonlinear optical experiments. The predictions from Bloch dynamics and responses including spectral diffusion are discussed. Experiments with the amide-I transitions of N-methylacetamide and the alanine dipetide show that Bloch dynamics are inadequate, but for small values of waiting times can give a reasonable description of the 2D spectra. Both single frequency and dual frequency 2D experiments that excite both the amide-I and amide-II modes are reported.