Enhanced photodesorption of NO on roughened silver surfaces

The photodesorption of NO at 458 nm on roughened silver is contrasted with that on Ag(111). The data for Ag(111) are discussed in terms of recent studies of the complex adsorption behaviour of this system; it is concluded that the most likely mechanism involves a substrate mediated dissociative electron attachment to the NO dimer followed by monomer NO desorption. A five-fold enhancement of the photodesorption cross section on the roughened surface is found on irradiation at 458 nm. It is suggested that this effect arises from an enhancement of the substrate-mediated process. Specifically it is proposed that surface plasmon excitation on the rough surface results in an enhanced hot electron yield, with the consequence of an enhanced cross section for photodesorption.