Spectroscopy and Photochemistry of Ethene, $C_{2}H_{4}$, on NaCl(100)

Abstract

The infrared spectra and thermodynamic behavior of ethene on a film of NaCl(100) crystallites, and on a single crystal of NaCl(100) was investigated. The structure of a physisorbed ethene monolayer on the single crystal surface was determined using polarized $FTIR^{1}$. We expand these studies to explore the photochemistry of the ethene adlayer. Photochemistry of small molecules physisorbed to alkali halides continues to show deviation from their gasphase characteristics. The substrate, once thought to be passive, influences both the static and dynamic behavior of adsorbed species. Triplet-triplet energy transfer from self-trapped excitions (STE) in NaCl was shown to significantly alter the photochemistry of adsorbed $acetylene^{2}$, $C_{2}H_{2}$. This energy transfer has now been found in the photodissociation of ethene on a film of NaCl(100) crystallites. These photochemical studies are now being explored on a single crystal of NaCl(100). $^{\ast}$ Supported by NSF grant CHE91-15444