Abstract

The frequency spectrum of the OH stretching vibration is strongly affected by the formation of hydrogen bonds. Unfortunately, the linear absorption spectrum of hydro gen-bonded OH stretching vibrations gives very little information on the dynamics of hydrogen bonds so that nonlinear spectroscopic studies are required. A recent nonlinear optical study using picosecond mid-infrared pulses showed that the predissociation of hydrogen bonds in the liquid phase on excitation of the OH stretching vibration is extremely fast and takes place on a time scale much shorter than the picosecond pulses used in this study.¹ Here we report on the first direct measurement of hydrogen- bond predissociation times in the liquid phase with use of intense femtosecond mid-infrared pulses. The technique is applied to the study of the dynamics of hydrogen-bonded ethanol dusters in an apolar solvent (CCl₄). Our experiments have enabled an accurate determination of the hydrogen bond predissociation time constant and its excitation frequency dependence.

© 1997 Optical Society of America