The transient response of 10 molecular layers of D2O ice on CO/Pt(1 1 1) at 130 K was investigated under ultra-high vacuum following a near-infrared pump pulse of 35 ps by sum frequency generation (SFG) spectroscopy. The D2O molecules in the ice crystalline layer formed an amorphous or liquid-like structure in response to the pumping without desorption of D2O to the gas phase, and the crystals returned to the crystal structure on a sub-nanosecond time scale. (C) 2003 Elsevier B.V. All rights reserved.