Optical and spin-selective time-of-flight measurement of light-induced desorption of Rb from Fe_3O_4 surfaces

Abstract

Light-induced desorption of Rb atoms from a ferrimagnetic Fe_3O_4(001) surface was studied using a spin-selective optical method, which provides information on the spin polarization, velocity distribution, and amount of the desorbed atoms. The results showed that the intensity of the desorption of Rb from Fe_3O_4(001) induced by ultraviolet (UV) light irradiation was smaller than the detection limit at coverages lower than the threshold coverage at which the desorption rate began to increase. Moreover, the average magnetic quantum number of the desorbed atoms was smaller than that of electrons at the Fermi level of the Fe_3O_4(001) surface. These indicate that the light-induced desorption of Rb from an Fe_3O_4(001) surface occurs only in the high-coverage region in which the desorbing atoms are not in contact with the Fe_3O_4 surface, and that the desorption does not involve spin transfer.