SEXAFS studies of CC bond lengths in condensed and chemisorbed molecules

Extended X-ray absorption fine structure (EXAFS) studies are reported above the carbon K-edge for solid benzene and cyclohexane. Both molecules exhibit pronounced EXAFS extending more than 500 eV above the edge. The measured EXAFS is in good agreement with single scattering simulations for the isolated molecules using a phase shift obtained from graphite data. We also explored the possibility of measuring the intra-molecular CC EXAFS for a chemisorbed molecule on a metal surface. Model calculations for a di-carbon species chemisorbed on Cu(100) reveals the feasibility of such studies for certain chemisorption geometries by use of a suitable sample orientation in the X-ray beam. © 1988.