Vibrational energy redistribution of ethanol oligomers and dissociation of hydrogen bonds after ultrafast infrared excitation

2-color infrared spectroscopy of associated ethanol molecules is carried out viith subpicosecond time resolution in the solvent carbon tetrachloride (1.2 M) at room temperature. After excitation of the CH-vibration at 2974 cm(-1) rapid population redistribution with a time constant < 0.5 ps is observed within the CH-stretching region in agreement with earlier observations, while an effective population lifetime of 12 +/- 2 ps is measured. In addition, amazingly fast dissociation of H-bonds occurs, the dominant component of which is governed by a time constant of approximately 2 ps and proposed to be of thermal origin. Further spectral features are discussed, e.g. energy transfer between CH- and OH-vibrations. (C) 1998 Elsevier Science B.V.