Photodesorption and photochemical dynamics on roughened silver: Sulphur dioxide and carbonyl sulphide

The photodesorption of SO2, both monolayer and multilayer, from roughened silver has been investigated. The photodesorption cross-section is enhanced by a factor of 2.6 ± 0.4 compared to the Ag(1 1 1) surface. The peak in the enhancement occurs at 340 nm. Time-of-flight mass spectrometry shows that the same mechanism operates on both the rough and Ag(1 1 1) surfaces. Coverage dependent experiments show that the enhancement is a first layer phenomenon, and coverage of greater than one monolayer effectively suppresses photodesorption. These data point to a surface plasmon resonance enhanced substrate mediated (hot electron attachment) photodesorption mechanism.