Different methods developed to induce a chemical reaction by photoexcitation will be reviewed and compared. It will be argued that interaction of a small, electronically-excited molecular system with an isolator surface has principal advantages over photochemistry with molecular adsorbates/aggregates and over photoexcitation in a pure gas-phase case. A model is proposed which describes the evolution of the molecular electronic excitation on its approach to an isolator surface and predicts a conversion of the electronic energy into kinetic motion directed primarily along the reaction coordinate. Alignment and “channelling” effects are expected within the resultant molecular flux reaching the surface and may result in a strong enhancement of the reaction yield. Finally, experimental results demonstrating the first surface chemical reaction with electronically excited molecules and a new experimental approach, capable of producing macroscopic fluxes of excited reagents, will be outlined [1.2]. Quantum yield for dissociative adsorption of electronically excited SO2 molecules on a surface was determined to be as high as 0.65±0.35, strongly supporting the validity of the given above general model.
1. J. J. Madhukeswara and V. V. Petrunin, Chem. Phys. Lett. 445, 309-314, 2007.
2. K.E. Pankin, J. J. Madhukeswara, A.R. Andersen, and V.V. Petrunin, to be published.
|Period||17. Oct 2007|
|Event title||A mechanism for chemical adsorption of electronically excited molecules on a surface: unexplored possibilities to control chemical transformations on interphases|