Chemical Bonding State of Chlorine on Ag{100} as Determined by Angle‐Resolved Secondary Ion Mass Spectrometry

Abstract

The power of the angle‐resolved ion desorption technique for straightforward characterization of surfaces is demonstrated. The structural sensitivity of secondary ion desorption has led to a successful application of angle‐resolved ion sputtering yield measurements to the determination of the Cl chemical bonding structure on the Ag {100} surface. Angular distributions of the sputtered Cl− ions show that chlorine dissociates at the surface to yield a bonding state of atomic form at the room temperature. Both the polar and the azimuthal angle dependencies of the sputter intensity for Ag+ and Cl− ions reveal that the Cl adatom is chemi‐sorbed high above the topmost substrate layer of Ag atoms. At all Cl exposures, the Ag‐Cl bond is oriented along the <100> azimuth with the adsorbate occupying a C4 symmetry site, not an a‐top, a bridge, or a high symmetry site. Shadow‐cone enhanced ion desorption spectra show that die geometrical structure of the Cl chemisorbed surface changes slightly as the exposure is increased.