Femtosecond infrared spectroscopy of the hydrogen bond in methanol: Vibrational and structural relaxation

We perform a 2-color pump-probe spectroscopy on femtosecond time scale in t he OH-stretching region of methanol oligomers dissolved in CCl4 at room tem perature. Measuring the isotropic component of the probe transmission, we o btain the relaxation time of the OH-stretching mode. It increases from 0,45 ps to 0,6 ps with the pump frequency from 3280 cm(-1) to 3400 cm(-1). We a lso observe a fast spectral relaxation and/or vibrational energy migration with breaking of the oligomers. Recombination then proceeds with a time con stant of 9 ps.