Surface Chemistry and Radiation Chemistry of Trifluoroiodomethane (CF_3I) on Mo(110)

摘要

The surface-induced and electron-induced chemistry of trifluoroiodomethane (CF_3I),a potential replacement for chlorofluorocarbons (CFCs) and chlorofluorobromocarbons (halons),were investigated under ultrahigh vacuum conditions (P approx 1 x 10~(-10) Torr) on Mo(110).Results of temperature-programmed desorption (TPD) experiments indicate that dissociative adsorption of CF_3I leads only to nonselective decomposition on Mo-(110),in contrast to reactions of CF_3I on other metal surfaces.Desorption of CF_3 radicals and atomic iodine was detected mass spectrometrically during low-energy (10-100 eV) electron irradiation of four monolayer thick films of CF_3I condensed at 100 K.Results of postirradiation temperature-programmed desorption experiments were used to identify CF_2I_2,C_2F_5I,C_2F_6,C_2F_4I_2,and CFI_3 as electron-induced reaction products of CF_3I.Except for CFI_3,all of these electron-induced reaction products of CF_3I have been previously identified in gamma-radiolysis studies,supporting our earlier claim that temperature-programmed desorption experiments conducted following low-energy electron irradiation of multilayer thin films provide an effective method to investigate the effects of high-energy radiation,including radical-radical reactions.