Femtosecond dynamics, two dimensional infrared spectroscopy and echoes of protein vibrations

Two approaches that use femtosecond infrared pulses to examine protein dynamics by means of nonlinear IR spectroscopy are described. In the first we dissect the featureless peptide amide-I band and introduce two-dimensional IR spectra [1]. In the second, the correlation function of the frequency fluctuations of a vibrational mode in the active site of carbonic anhydrase and heme pocket of hemoglobin is determined by three-pulse IR photon echoes [2]. These experiments permit the study of ultrafast dynamics without the requirement of chromophores.