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Inelastic electron scattering by long-wavelength, acoustic phonons; image potential modulation as a mechanism
A274 584 AMMONIA
Surface Science 155 (1985) 584-595 North-HoUand, Amsterdam ADSORPTION
O N T H E Ag(311) S U R F A C E
S.T. C E Y E R * a n d J.T. Y A T E S , Jr. **
Surface Science Division, National Bureau of Standards, Gaithersbur~ Mar))land 20899, USA Received 28 September 1984; accepted for publication 26 December 1984 The adsorption of ammonia on the Ag(311) surface has been studied by ESDIAD (electron stimulated desorption-ion angular distributions), high resolution electron energy loss spectroscopy and thermal desorption spectroscopy. Two desorption peaks are observed in the thermal desorption spectra and are correlated with two bonding geometries. The more strongly bound state corresponds to ammonia bound on top of the ridge atom through the nitrogen end with its C3v axis perpendicular to the macroscopic surface. It is suggested that the less strongly bound state corresponds to ammonia molecules lying down in the troughs.
596
Surface Science 155 (1985) 596-606 North-Holland, Amsterdam
VAN DER WAALS INTERACTION OF RARE GASES AND HYDROGEN ON SEMICONDUCTOR SURFACES K. N A T H , Z . W . G O R T E L
* a n d H.J. K R E U Z E R
Department of Physics, Dalhousie University Halifax, NS, Canada B3H 3J5 Received 24 September 1984; accepted for publication 17 January 1985 We calculate the Van der W~als constants of rare gases and hydrogen on 20 semiconductors using experimental data on the dielectric function.
Surface Science 155 (1985) 607-628 North-Holland, Amsterdam
607
INELASTIC ELECTRON SCATI'ERING BY LONG-WAVELENGTH, ACOUSTIC PHONONS; IMAGE POTENTIAL MODULATION AS A MECHANISM J.C. A R I Y A S U
and D.L. MILLS
Department of Physics, University of California, lrvine, California 92717, USA Received 31 August 1984; accepted for publication 7 December 1984 Acoustic phonons may scatter electrons inelastically from crystal surfaces. While the small energy transfers involved may not be directly measured, such processes may contribute to broadening of the quasi-elastic beam as it reflects off of the surface. We explore one possible mechanism for such scattering processes: the modulation of the image potential through the ripples in surface profile created by thermally excited substrate (surface and bulk) phonons. We compare our results with those of an earlier study, and with the scattering produced by the dynamic dipole moment of the surface atoms.
Surface Science 155 (1985) 584-595 North-HoUand, Amsterdam ADSORPTION
O N T H E Ag(311) S U R F A C E
S.T. C E Y E R * a n d J.T. Y A T E S , Jr. **
Surface Science Division, National Bureau of Standards, Gaithersbur~ Mar))land 20899, USA Received 28 September 1984; accepted for publication 26 December 1984 The adsorption of ammonia on the Ag(311) surface has been studied by ESDIAD (electron stimulated desorption-ion angular distributions), high resolution electron energy loss spectroscopy and thermal desorption spectroscopy. Two desorption peaks are observed in the thermal desorption spectra and are correlated with two bonding geometries. The more strongly bound state corresponds to ammonia bound on top of the ridge atom through the nitrogen end with its C3v axis perpendicular to the macroscopic surface. It is suggested that the less strongly bound state corresponds to ammonia molecules lying down in the troughs.
596
Surface Science 155 (1985) 596-606 North-Holland, Amsterdam
VAN DER WAALS INTERACTION OF RARE GASES AND HYDROGEN ON SEMICONDUCTOR SURFACES K. N A T H , Z . W . G O R T E L
* a n d H.J. K R E U Z E R
Department of Physics, Dalhousie University Halifax, NS, Canada B3H 3J5 Received 24 September 1984; accepted for publication 17 January 1985 We calculate the Van der W~als constants of rare gases and hydrogen on 20 semiconductors using experimental data on the dielectric function.
Surface Science 155 (1985) 607-628 North-Holland, Amsterdam
607
INELASTIC ELECTRON SCATI'ERING BY LONG-WAVELENGTH, ACOUSTIC PHONONS; IMAGE POTENTIAL MODULATION AS A MECHANISM J.C. A R I Y A S U
and D.L. MILLS
Department of Physics, University of California, lrvine, California 92717, USA Received 31 August 1984; accepted for publication 7 December 1984 Acoustic phonons may scatter electrons inelastically from crystal surfaces. While the small energy transfers involved may not be directly measured, such processes may contribute to broadening of the quasi-elastic beam as it reflects off of the surface. We explore one possible mechanism for such scattering processes: the modulation of the image potential through the ripples in surface profile created by thermally excited substrate (surface and bulk) phonons. We compare our results with those of an earlier study, and with the scattering produced by the dynamic dipole moment of the surface atoms.