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On the quantum Debye-Waller factor in atom-surface scattering: Angular and temperature dependence
A302 Surface Science 119 (1982) 371-383 North-Holland Publishing Company
371
ANGLE-RESOLVED X-RAY PHOTOEMISSION FROM CORE LEVELS O F c(2 X 2) C O O N Ni(001): S l N G L E - S C A ' I T E R I N G THEORY AND EFFECTS P.J. O R D E R S ,
OF VIBRATION* S. K O N O * * , C.S. F A D L E Y , R. T R E H A N
a n d J.T. L L O Y D * * *
Department of Chemistry, University of Hawaii, 2545 The Mall, Honolulu, Hawaii 96822, USA Received 28 October 1981 ; accepted for publication 24 March 1982 The effects of bending or frustrated rotatipnal vibrations of adsorbed CO on photoelectron diffraction in core-level angle-resolved X-ray photoelectron spectroscopy (ARXPS) are examined by means of single-scattering calculations and direct measurement. The results of the calculations, which cover a physically reasonable range of values for the average vibrational amplitude, are compared with ARXPS measurements of the C ls photoelectron intensity from c(2×2) CO on Ni(001). Both intramolecular scattering effects in polar scans and intermolecular scattering effects in azimuthal scans are considered. Such comparisons show that, even in the presence of considerable vibration, it is possible to derive valuable information about the bonding orientation and short-range order of such adsorbed molecular overlayers.
384
Surface Science 119 (1982) 384 390 North-Holland Publishing Company
ON THE QUANTUM DEBYE-WALLER FACTOR IN ATOM-SURFACE SCATTERING: ANGULAR AND TEMPERATURE
DEPENDENCE
N. GARCiA
Departamento de Fisica Fundamental, Universidad Aut6noma de Madrid, Canto Blanco, Madrid-34, Spain and A.A. MARADUDIN
*
Max-Planck-lnstitut fiir Festk6rperforschung, Heisenbergstrasse 1, D-7000 Stuttgart 80, Fed Rep. of Germany Received 8 December 1981; accepted for publication 6 March 1982 We present a theory and calculations for the Debye-Waller factor in atom scattering from a flat hard surface that take into account multiple scattering effects through the cross-correlation of surface atom displacements coupled to the momentum of the incident particle. We use for the phonon spectrum a continuum model with longitudinal, transverse, and Rayleigh waves. The calculations are done for all temperatures and angles of incidence. It is found that the effective mean square displacement is reduced by a factor of - - 1 / 2 overall for surface temperatures T~ larger than 100 K, and by a factor ~ 1/3 to ~ 1/30 for ~ = 10 K.
371
ANGLE-RESOLVED X-RAY PHOTOEMISSION FROM CORE LEVELS O F c(2 X 2) C O O N Ni(001): S l N G L E - S C A ' I T E R I N G THEORY AND EFFECTS P.J. O R D E R S ,
OF VIBRATION* S. K O N O * * , C.S. F A D L E Y , R. T R E H A N
a n d J.T. L L O Y D * * *
Department of Chemistry, University of Hawaii, 2545 The Mall, Honolulu, Hawaii 96822, USA Received 28 October 1981 ; accepted for publication 24 March 1982 The effects of bending or frustrated rotatipnal vibrations of adsorbed CO on photoelectron diffraction in core-level angle-resolved X-ray photoelectron spectroscopy (ARXPS) are examined by means of single-scattering calculations and direct measurement. The results of the calculations, which cover a physically reasonable range of values for the average vibrational amplitude, are compared with ARXPS measurements of the C ls photoelectron intensity from c(2×2) CO on Ni(001). Both intramolecular scattering effects in polar scans and intermolecular scattering effects in azimuthal scans are considered. Such comparisons show that, even in the presence of considerable vibration, it is possible to derive valuable information about the bonding orientation and short-range order of such adsorbed molecular overlayers.
384
Surface Science 119 (1982) 384 390 North-Holland Publishing Company
ON THE QUANTUM DEBYE-WALLER FACTOR IN ATOM-SURFACE SCATTERING: ANGULAR AND TEMPERATURE
DEPENDENCE
N. GARCiA
Departamento de Fisica Fundamental, Universidad Aut6noma de Madrid, Canto Blanco, Madrid-34, Spain and A.A. MARADUDIN
*
Max-Planck-lnstitut fiir Festk6rperforschung, Heisenbergstrasse 1, D-7000 Stuttgart 80, Fed Rep. of Germany Received 8 December 1981; accepted for publication 6 March 1982 We present a theory and calculations for the Debye-Waller factor in atom scattering from a flat hard surface that take into account multiple scattering effects through the cross-correlation of surface atom displacements coupled to the momentum of the incident particle. We use for the phonon spectrum a continuum model with longitudinal, transverse, and Rayleigh waves. The calculations are done for all temperatures and angles of incidence. It is found that the effective mean square displacement is reduced by a factor of - - 1 / 2 overall for surface temperatures T~ larger than 100 K, and by a factor ~ 1/3 to ~ 1/30 for ~ = 10 K.