Vibrational Dynamics of Hydrogen-Bonded Complexes Studied by Infrared Pump-Probe Spectroscopy

Abstract

We have investigated vibrational dynamics of hydrogen-bonded complexes in solutions by sub-picosecond infrared (IR) pump-probe spectroscopy. The anharmonic coupling between the OH stretching mode of benzoic acid dimer and low-frequency mode was studied from analysis of the quantum beat observed in the pump-probe signal. The IR absorption spectrum of 9-fluorenone (FL) in alcohol shows three distinct contributions from the free FL, its complex with one alcohol molecule, and that with two molecules. The time constants of the vibrational energy relaxation (VER) of the CO stretching mode of the free FL and that of the 1:1 complex were obtained. The VER of the OH stretching mode of methanol was studied in the isotopically diluted methanol. The internal isotope effect on the VER is discussed.