Transient responses of SFG spectra of D2O ice/CO/Pt(1 1 1) interface with irradiation of ultra-short NIR pump pulses

The behavior of D2O ice on CO/Pt(1 1 1) and Pt(1 1 1) under the irradiation of near-IR pulses (NIR) was studied by sum-frequency generation (SFG) spectroscopy. The peaks assigned to the O–D stretching modes of ice were obtained for the first 30 molecular layers on Pt(1 1 1). When the D2O/CO/Pt(1 1 1) was irradiated, the signal of D2O was weakened after 500 ps, but that of CO was weakened immediately after the pumping. A similar time response was observed for the D2O peak in D2O/Pt(1 1 1). The weakening of SFG is attributed to the broadening of bands due to thermal excitation. This indicates that the energy of the pump pulse is deposited on the Pt(1 1 1) surface and diffused into the layers of D2O ice in the 500 ps timescale.