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Interaction of low-energy electrons with SO[sub 2] layers on Ag(111): Comparison to photochemistry

Journal Article · · Journal of Physical Chemistry; (United States)
DOI:https://doi.org/10.1021/j100106a016· OSTI ID:6521281
; ;  [1];  [2]
  1. Univ. of Texas, Austin (United States)
  2. Oklahoma State Univ., Stillwater (United States)
The interaction of low-energy electrons (8-54eV) with SO[sub 2] layers on Ag(111) has been studied using temperature programmed desorption (TPD) and Auger electron spectroscopy (AES). For coverages up to one monolayer, the only electron-stimulated desorption (ESD) process is parent desorption, which has a cross section of 3.6 [+-] 0.8 [times] 10[sup [minus]17] cm[sup 2] using 54 [+-] 1 eV electrons. This ESD process has an electron energy threshold of 18.0 [+-] 1.0 eV corresponding to ionization of the 6a[sub 1] molecular orbital of adsorbed SO[sub 2]. For coverages greater than one monolayer, ESD is accompanied by electron-induced decomposition (EID) and the total cross section for loss of SO[sub 2] is [approx] 10[sup [minus]16]cm[sup 2] independent of coverage up to 8 monolayers (ML). The differences between chemisorbed and physisorbed layers is attributed mainly to metal-induced quenching of electronically excited adsorbates, which is less important for those SO[sub 2] molecules further from the metal. Compared to photon-driven desorption, electron-driven desorption follows a different excitation pathway, which we attribute to the formation of transient positive ions. 47 refs., 11 figs., 1 tab.
OSTI ID:
6521281
Journal Information:
Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 97:4; ISSN JPCHAX; ISSN 0022-3654
Country of Publication:
United States
Language:
English