OBSERVATION OF THE SELF-QUENCHING OF THERMALIZED-ELECTRON-MEDIATED PHOTOCHEMISTRY ON SEMICONDUCTOR SURFACES

[摘要] We show that the ''thermalized'' electron-mediated photodissociation of CH3Br on GaAs(110) is self-quenched as the reaction occurs. The photoreaction rate, as measured by the ejected CH3 flux, decreases rapidly as the surface is irradiated. Photoluminescence measurements on the substrate show that the reduction in the rate is due to a decrease in the lifetime of excited electrons which have relaxed to the conduction band edge. This reduced carrier lifetime results from enhanced surface recombination via Br-induced surface states. It is suggested that such self-quenching may be a common consideration for thermalized, photoexcited-carrier-induced reactions on semiconductor surfaces.

[发布日期] 1993-12-10