THE THERMAL CHEMISTRY OF ETHYL IODIDE CHEMISORBED ON NI(100)

The interaction of ethyl iodide with Ni(100) surfaces has been examine d by using thermal programmed desorption (TPD), X-ray photoelectron (X PS), and static secondary ion mass (SSIMS) spectroscopies. Ethyl iodid e adsorbs molecularly on that surface below 100 K, and dissociates bet ween 100 and 160 K to form ethyl species and iodine atoms. At low cove rages the ethyl moieties decompose completely to form surface carbon a nd hydrogen atoms (which recombine and desorb at slightly above 300 K) , but desorption of both ethylene and ethane is also observed at highe r coverages. Ethylene forms via the elimination of a hydrogen atom fro m the beta position, and desorbs between 160 and 210 K depending on th e initial coverage of ethyl iodide; ethane, on the other hand, is gene rated mostly by a direct recombination of ethyl species with hydrogen originating either from adsorption of background gases or from the bet a-hydride elimination reaction.