Direct observation of short-lived unstable surface species by tunable picosecond infrared pulses

By means of a tunable infrared pump-probe technique, the transient absorption spectrum of the vibrationally excited OD group of a water molecule adsorbed on the deuterated mordenite zeolite (DM-20) was measured. A short-lived transient signal (≈ 15 ps) indicating a newly appeared surface species was observed.