Desorption of water from iron oxide by laser irradiation

Desorption of water adsorbed on iron oxide by laser irradiation was studied by means of a time-of-flight (TOF) technique. Laser wavelength of λ=355 and 430 nm were used. The dependence of the velocity distribution of desorbed water on the temperature (246–324 K) of the iron oxide and on the adsorption state of water were investigated. The desorption mechanism of water from the iron oxide which is in the form of OH is not dependent on the temperature (246–324 K) of the iron oxide. The desorption by laser irradiation at λ=430 nm from iron oxide on which water is molecularly adsorbed on the surface OH at 229 K is considered to be initiated by the two series of steps: (1) surface OH captures the electron excited in the iron oxide and gains kinetic energy; (2) this energy transfers to the water molecules which are molecularly adsorbed near this OH.