TITLE: Toward Understanding Photoemission in K + CO Coadsorption Systems.

AUTHOR: P. A. Shultz.

INST.  AUTHOR: Sandia National Labs., Albuquerque, NM.

SPONSOR: Department of Energy, Washington, DC.

LANGUAGE: English

PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  1989,  20p.

NTIS ORDER NO.: DE90002577INW

ABSTRACT:

Alkali-induced changes in electronic energy levels, observed in photoemission from CO on transition metal surfaces, are examined theoretically and shown to be consistent with the formation of two-dimensional ionic islands in the coadsorbed system. A point charge model is applied to the K + CO system to calculate the levels. The analysis reveals that significant screening of the CO levels, by the extra electron in the K-modified anion, is masked by an equally large electrostatic stabilization of the electrons on the CO site by the Madelung potential ((approximately)8 eV) of the K(sup +) -- CO(sup -) layer. The model explains the splitting of the 1(pi)-derived level, by (approximately)1 eV, without requiring any symmetry lowering of the molecular geometry. The results are in reasonable agreement with experimental observations and compare favorably with more sophisticated calculations. 37 refs., 1 fig., 2 tab.

REPORT  NUMBER: SAND-89-1318C;   CONF-891093-14

CONTRACT  NUMBER: AC04-76DP00789