Transient spectral hole burning and hydrogen-bond breaking determined in different solutions of ethanol in deuterated ethanol

We present data on time-resolved infrared spectroscopy of ethanol diluted i n deuterated ethanol at two concentrations of 1 and 50 vol % and excitation within the OH-stretching band. Transient spectral holes with widths of 35- 55 cm(-1) and 25 cm(-1), respectively, are determined as well as breaking o f hydrogen bonds after vibrational excitation. The lifetime of the OH mode of associated ethanol depends on the strength of the H bond and varies betw een <1 ps and 1.5+/-0.5 ps. While at the lower concentration the thermal ef fect due to the deposited energy is negligible, the higher concentration re sults in a pronounced heating of the excited molecules. Two different relax ation mechanisms of the excited OH mode of associated ethanol are discussed . (C) 1999 American Institute of Physics. [S0021-9606(99)51312-3].