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Cesium and oxygen coadsorption on LaB6 single crystal surfaces
A245 unit-cell directions with an amplitude of 0.18-+0.02 A. A discussion of the total corrugation amplitudes of MgO and NiO on the one side and of LiF and NaCI on the other, in connection with the ionic ~:adii of the respective constituents, provides evidence that the ionic bonding is largely maintained at the surface of the alkali halides, but that an appreciable charge redistribution takes place at the surface of the oxides.
66
Surface Science 118 (1982) 66-74 North-Holland Publishing Company
STUDY OF ANGULAR FACTORS IN SPUTI'ER-DEPOSITION USING THE ION BEAM METHOD T. M O T O H I R O and Y. T A G A Toyota Central Research and Development Laboratories, Inc., Nagakute-cho, Aichi-gun, Aichi Pref. 480-11, Japan
and K. N A K A J I M A Toyota Technological Institute, Hisakata, Tempaku-ku, Nagoya, Japan Received 30 October 1981; accepted for publication 2 March 1982 Effects of angular factors on film formation in a sputter-deposition system were studied. Twenty Si(100) substrates were set in a vacuum system in different angular conditions. Ag or SiO 2 films were simultaneously deposited on their surfaces using the Xe + (0.5 or 1.5 keV) ion beam sputter-deposition method. Morphology and thickness of the films were examined by SEM and EPMA. The findings revealed a strong dependence of 0, the radiation angle of particles sputtered from a target, and 8, the incident angle at which the particles enter the surface, on the morphology and the deposition rate of the film. These results are discussed from the standpoints of (i) the angular dependence of the energy distribution on the sputtered particles, and (ii) the angular and energy dependence of the sticking probability with which the particles adhere to the substrate.
Surface Science 118 (1982) 75-92 North-Holland Publishing Company
75
CESIUM AND OXYGEN COADSORPTION ON Lai~ SINGLE CRYSTAL SURFACES I. Work function change S.A. C H A M B E R S Division of Natural Science, George Fox College, Newberg, Oregon 97132, USA
and P.R. DAVIS, L.W. SWANSON and M.A. GESLEY Department of Applied Physics and Electronic Science, Oregon Graduate Center, Beaverton, Oregon 97006, USA Received 8 June 1981; accepted for publication 2 March 1982 The coadsorption properties of Cs and oxygen on LaBs (100) and (110) have been investigated using Auger electron spectroscopy and the FERP method of work function measurement. It is found that adsorption of Cs on the clean surfaces results in work function minima 4~m of 1.97 and
A246 1.88 eV for the (100) and (110) surfaces, respectively, whereas Cs adsorption onto the surfaces with preadsorbed oxygen results in ~m values of 1.35 and 1.47 eV. Auger data suggest that oxygen adsorbs preferentially at B sites but that La surface atoms are involved in the bonding. Oxygen precoverage increases the ionic character of the Cs bond as well as the Cs coverage at 4'm. At room temperature there is no evidence of multilayer Cs adsorption. The work function/coverage relationships are compared with two different models.
Surface Science 118 (1982) 93-102 North-Holland Publishing C o m p a n y CESIUM
AND
OXYGEN
CRYSTAL
SURFACES
I1. T h e r m a l
desorption
93
COADSORPTION
ON
LaB n SINGLE
of cesium from LaB 6 (100)
S.A. CHAMBERS
Division of Natural Seience, George Fox College, Newberg, Oregon 97132, USA and P.R. DAVIS
and L.W. SWANSON
Department of Applied Physics and Electronic Science, Oregon Graduate ('enter, Beaverton, Oregon 97006, USA Received 8 June 1981; accepted for publication 2 March 1982 Thermal desorption of neutral Cs from LaB6 (100) with and without preadsorbed oxygen occurs from discrete binding states at high Cs coverage and a continuum of states at low coverage. The two discrete binding states have activation energies of 1.2 and 1.5 eV on clean LAB6(100) which shift to 1.4 and 1.7 eV with oxygen preadsorption and are independent of Cs coverage. The terminal coverage Cs desorption energy increases from 2.3 to 3.0 eV as a result of an oxygen underlayer, consistent with the formation of C s - O bonds between the two chemisorbed layers. The adsorption of Cs on either surface is apparently limited to a single layer at room temperature. Cs ion desorption is observed from the oxygen covered surface at low (Oc~<~0.08) coverage with an evaporation energy of 2.5 eV. All Cs desorption reactions occurring on these surfaces are shown to be first-order processes.
Surface Science 118 (1982) 103-120 North-Holland Publishing C o m p a n y A HELIUM OF
OXYGEN
BEAM ON
J. L A P U J O U L A D E , and
SCATTERING
103 STUDY
OF THE
ADSORPTION
COPPER (110) Y. LE CRUER,
M. LEFORT,
Y. LEJAY
E. M A U R E L
Centre d'Etudes Nuclbaires de Saclay, Service de Physique A tomique, F-91191 Gif-sur- Yvette Cedex, France Received 21 July 1981; accepted for publication 26 February 1982 The scattering of a helium nozzle beam by an oxygen layer adsorbed on Cu(110) has been experimentally studied. The intensity of diffraction peaks, resonances with bound states and temperature dependence of the intensities (Debye-Waller factor) are reported. The main feature of
66
Surface Science 118 (1982) 66-74 North-Holland Publishing Company
STUDY OF ANGULAR FACTORS IN SPUTI'ER-DEPOSITION USING THE ION BEAM METHOD T. M O T O H I R O and Y. T A G A Toyota Central Research and Development Laboratories, Inc., Nagakute-cho, Aichi-gun, Aichi Pref. 480-11, Japan
and K. N A K A J I M A Toyota Technological Institute, Hisakata, Tempaku-ku, Nagoya, Japan Received 30 October 1981; accepted for publication 2 March 1982 Effects of angular factors on film formation in a sputter-deposition system were studied. Twenty Si(100) substrates were set in a vacuum system in different angular conditions. Ag or SiO 2 films were simultaneously deposited on their surfaces using the Xe + (0.5 or 1.5 keV) ion beam sputter-deposition method. Morphology and thickness of the films were examined by SEM and EPMA. The findings revealed a strong dependence of 0, the radiation angle of particles sputtered from a target, and 8, the incident angle at which the particles enter the surface, on the morphology and the deposition rate of the film. These results are discussed from the standpoints of (i) the angular dependence of the energy distribution on the sputtered particles, and (ii) the angular and energy dependence of the sticking probability with which the particles adhere to the substrate.
Surface Science 118 (1982) 75-92 North-Holland Publishing Company
75
CESIUM AND OXYGEN COADSORPTION ON Lai~ SINGLE CRYSTAL SURFACES I. Work function change S.A. C H A M B E R S Division of Natural Science, George Fox College, Newberg, Oregon 97132, USA
and P.R. DAVIS, L.W. SWANSON and M.A. GESLEY Department of Applied Physics and Electronic Science, Oregon Graduate Center, Beaverton, Oregon 97006, USA Received 8 June 1981; accepted for publication 2 March 1982 The coadsorption properties of Cs and oxygen on LaBs (100) and (110) have been investigated using Auger electron spectroscopy and the FERP method of work function measurement. It is found that adsorption of Cs on the clean surfaces results in work function minima 4~m of 1.97 and
A246 1.88 eV for the (100) and (110) surfaces, respectively, whereas Cs adsorption onto the surfaces with preadsorbed oxygen results in ~m values of 1.35 and 1.47 eV. Auger data suggest that oxygen adsorbs preferentially at B sites but that La surface atoms are involved in the bonding. Oxygen precoverage increases the ionic character of the Cs bond as well as the Cs coverage at 4'm. At room temperature there is no evidence of multilayer Cs adsorption. The work function/coverage relationships are compared with two different models.
Surface Science 118 (1982) 93-102 North-Holland Publishing C o m p a n y CESIUM
AND
OXYGEN
CRYSTAL
SURFACES
I1. T h e r m a l
desorption
93
COADSORPTION
ON
LaB n SINGLE
of cesium from LaB 6 (100)
S.A. CHAMBERS
Division of Natural Seience, George Fox College, Newberg, Oregon 97132, USA and P.R. DAVIS
and L.W. SWANSON
Department of Applied Physics and Electronic Science, Oregon Graduate ('enter, Beaverton, Oregon 97006, USA Received 8 June 1981; accepted for publication 2 March 1982 Thermal desorption of neutral Cs from LaB6 (100) with and without preadsorbed oxygen occurs from discrete binding states at high Cs coverage and a continuum of states at low coverage. The two discrete binding states have activation energies of 1.2 and 1.5 eV on clean LAB6(100) which shift to 1.4 and 1.7 eV with oxygen preadsorption and are independent of Cs coverage. The terminal coverage Cs desorption energy increases from 2.3 to 3.0 eV as a result of an oxygen underlayer, consistent with the formation of C s - O bonds between the two chemisorbed layers. The adsorption of Cs on either surface is apparently limited to a single layer at room temperature. Cs ion desorption is observed from the oxygen covered surface at low (Oc~<~0.08) coverage with an evaporation energy of 2.5 eV. All Cs desorption reactions occurring on these surfaces are shown to be first-order processes.
Surface Science 118 (1982) 103-120 North-Holland Publishing C o m p a n y A HELIUM OF
OXYGEN
BEAM ON
J. L A P U J O U L A D E , and
SCATTERING
103 STUDY
OF THE
ADSORPTION
COPPER (110) Y. LE CRUER,
M. LEFORT,
Y. LEJAY
E. M A U R E L
Centre d'Etudes Nuclbaires de Saclay, Service de Physique A tomique, F-91191 Gif-sur- Yvette Cedex, France Received 21 July 1981; accepted for publication 26 February 1982 The scattering of a helium nozzle beam by an oxygen layer adsorbed on Cu(110) has been experimentally studied. The intensity of diffraction peaks, resonances with bound states and temperature dependence of the intensities (Debye-Waller factor) are reported. The main feature of