RESUMO
Water molecules are photo-ejected upon laser irradiation from the surface of ice films grown on graphite (0001) and Pt(111). The films are deposited at temperatures between 40 and 140 K and irradiated with nanosecond laser pulses. The process is investigated in the wavelength range between 275 and 670 nm. The wavelength and photon flux dependence suggest a multi-photon process with energy threshold of around 9 eV. The photo-detachment is less effective or negligible from films annealed at temperatures above the amorphous-crystalline transition temperature of ice films. Coverage dependence of the phenomena relates the photo yield to surface roughness. Electronic excitation mechanism related to the defects in ice is proposed to explain the observations.
