Picosecond infrared pump-probe spectrum of D₂O adsorbed at acid OD group of zeolite

Spectroscopic and dynamic features of the vibrationally excited D₂O/zeolite system have been investigated by two-color infrared-infrared pump-probe experiment. The frequency- and delay-scanned probe intensities were measured by tuning the pump laser to the OD stretching bands of the D₂O molecule hydrogen bonded to the acidic OD group of mordenite zeolite. Two types of pump-induced signals were observed: the ones which have the population lifetime of 43±5 ps and display frequency shift by the pumping frequency, and the others, which have the lifetime of about 15 ps and exhibit no such frequency shift. Possible origins of the signals are discussed.