SYNCHROTRON-RADIATION-INDUCED REACTIONS ON SURFACES - MECHANISMS AND APPLICATIONS

In this paper we tabulate recent research that delves into the applica tion of synchrotron radiation for inducing surface chemical reactions. We then present results from recent experiments designed to test whet her surface photochemical reactions can be brought about by direct cor e-level excitation of the adsorbate, as opposed to an indirect mechani sm where photoabsorption by bulk atoms produces secondary electrons th at cause the reaction. Experiments were performed on SiF4 adsorbed on Ge(100) at 30 K. It was found that direct excitation of Si 2p core lev els causes the reaction to occur. Finally we show the application of X -ray dependent surface photochemistry in two systems of technological relevance. The first is adamantane (C10H16) adsorbed on Si(111) at 85 K. X-rays with energies greater than the CK edge (284 eV) cause signif icant bond breaking and the formation of SiC. Lower energy X-rays appe ar to create adamantyl radicals which bond strongly with the substrate and are stable to 625 K. The second is Teflon where irradiation with photons with energies lower than 12 eV induces the desorption of relat ively large fluorocarbon fragments, as compared to photolysis with pho tons of energies greater than 22 eV (C2s excitation).