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Title: Supression of electron-induced positive ion emission by a molecular overlayer: Ion-molecule charge exchange at a surface

Journal Article · · Physical Review Letters; (United States)
;  [1]
  1. Department of Physics and Astronomy and Laboratory for Surface Modification, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08855-0849 (United States)

We report the suppression of electron-stimulated desorption of positive ions (O[sup +] and F[sup +]) from a TiO[sub 2] (110) surface caused by adsorption of a fractional monolayer of molecular NH[sub 3]. A linear decrease of O[sup +] and F[sup +] emission with NH[sub 3] coverage is observed. This system allows us to distinguish between neutralization of desorbing ions via interaction with the substrate or with adsorbed molecules. We propose a novel charge exchange mechanism where electron transfer from the occupied orbitals of the adsorbed molecules to the desorbing ions causes the decrease in detected ion yield. Charge transfer cross sections of 2.8([plus minus]0.5) and 2.7([plus minus]1) ([times]10[sup [minus]15]) cm[sup 2] have been determined for O[sup +] and F[sup +] ions, respectively.

OSTI ID:
5172075
Journal Information:
Physical Review Letters; (United States), Vol. 72:7; ISSN 0031-9007
Country of Publication:
United States
Language:
English