Vacuum ultraviolet photodissociation and surface morphology change of water ice films dosed with hydrogen chloride

摘要

Time-of-flight(TOF)spectra of photofragment H atoms from the photodissociation of water ice films at 193 nm were measured for amorphous and polycrystalline water ice films with and without dosing of hydrogen chloride at 100-145 K.The TOF spectrum is sensitive to the surface morphology of the water ice film because the origin of the H atom is the photodissociation of dimerlike water molecules attached to the ice film surfaces.Adsorption of HCl on a polycrystalline ice film was found to induce formation of disorder regions on the ice film surface at 100-140 K,while the microstructure of the ice surface stayed of polycrystalline at 145 K with adsorption of HCl.The TOF spectra of photofragment Cl atoms from the 157 nm photodissociation of neutral HCl adsorbed on water ice films at 100-140 K were measured.These results suggest partial dissolution of HCl on the ice film surface at 100-140 K.