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 with 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.