Spectroscopic Photoresponse of the Passive Film Formed on Iron

Publisher Website
Google Scholar
Abstract
Spectroscopic photoresponse of the passive film formed on iron in neutral borate solution was studied. The spectroscopic three parameter reflectometry and the photoelectrochemical technique were employed to obtain the spectra of absorption coefficient and photocurrent. From these spectra, a conversion efficiency, η, from the flux of photons absorbed in the film to the photocurrent was calculated as a function of photon energy. The result shows that the photoexcitation process of electron‐hole‐pair formation includes two transition mechanisms; a direct allowed transition and an indirect allowed transition. The direct transition, which occurs in the photon energy higher than 2.6 eV, is attributed to the excitation between the valence (O‐2p) and the conduction (Fe‐3d) bands of iron oxide, whereas the indirect transition, which occurs in the photon energy higher than 0.8 eV, is associated with electronic levels of impurities or d‐d transition in the passive film. The maximum value of η observed at a photon energy of 3.1 eV is about 20%, and this high efficiency suggests that the high electric field exists in the passive film of iron.
Keywords

This publication has 0 references indexed in Scilit: