Laser-pulsed thermal chemistry: UV laser-activated oxidation of niobium

Surface oxidation of niobium metal has been studied under pulsed UV laser (λ=308 nm) exposure at one atmosphere of oxygen. Diffusion apears to dominate this laser-pulsed thermal chemistry (LPTC) reaction. X-ray photoelectron spectroscopy reveals a range of niobium oxidation states Nb +5, Nb+4, Nb+2, and Nb metal from the surface to the bulk, respectively. LPTC oxidation depth increases monotonically with repeated laser irradiation unlike infrared laser-induced pulsed plasma chemistry, which is self-limiting. Possible electronic contributions to the LPTC process are considered as well as effects due to surface crystal orientation. © 1984 American Institute of Physics.