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ESDIAD from CO on W(100): Evidence for non-vertically adsorbed CO
A89 Surface Science 93 (1980) 71-83 0 North-Holland Publishing Company
ESDIAD FROM CO ON W( 100): EVIDENCE FOR NON-VERTICALLY ADSORBED CO R. JAEGER * and D. MENZEL Physik Department E 20, Institut fiir Festktirperphysik, D-8046 Garching, FR Germany
Technische
Universitci’tMiinchen,
Received 31 July 1979; accepted for publication 23 October 1979 Mass-discriminating measurements of the angular distributions of electron-stimulated ion desorption (ESDIAD) from CO adsorbed on W(100) and coadsorbed with C and 0 have been performed. The O* beams indicate normal and off-normal (by 5 to 13”) desorption which is interpreted as due to CO molecules bound in symmetric and in two types of unsymmetric bridges. Preadsorption of C suppresses the vertical state, while oxidation of the surface suppresses the off-normal states.
Surface Science 93 (1980) 84-106 0 North-Holland Publishing Company
THE INFLUENCE OF NON-RADIATIVE TRANSITIONS ON BOMBARDMENT INDUCED PHOTON EMISSION FROM Ti AND Ti OXIDE C.M. LOXTON, R.J. MacDONALD and P.J. MARTIN Department
of Physics, The Australian National University, Canberra, Australia 2601
Received 4 June 1979; accepted for publication 12 October 1979 Photon yields from Ti atoms sputtered from Ti and Ti oxide due to 55 keV Ar+ and 0; ion bombardment have been studied. Photon yields and line profiles of selected lines have also been studied as a function of background 02 exposure. An attempt has been made to correlate changes in yields and line shapes with variations of the band structure in the solid. Resonance ionization processes are shown not to contribute to the observed yield, however Auger processes cannot be excluded. Lifetime effects have a strong influence on the observed results. It is shown that the distribution of excited states produced by the ion bombardment is Boltzmannlike. We note that it is possible to interpret these results in terms of a model which assumes that the probability of excitation or ionization is exponentially dependent on the excitation or ioniration energy, without invoking electron exchange mechanisms.
Surface Science 93 (1980) 107-116 0 North-Holland Publishing Company
LASER INDUCED CHARGE TRANSFER FROM Ni TO CO ADSORBED ON (111) AND (110) SURFACES * H.W. RUDOLF and W. STEINMANN Sektion Physik der Universitlit Miinchen, Schellingstrasse 4. D-8000 Miinchen 40, Germany
Received 21 August 1979; accepted for publication 5 November 1979 Ni( 110) and (111) surfaces covered with up to one monolayer of CO were irradiated with the light of a dye laser in the photon energy range 2.0 to 3.4 eV. Two-photon photoemission was observed when the laser light was focussed. Upon defocussing a signal was measured which
ESDIAD FROM CO ON W( 100): EVIDENCE FOR NON-VERTICALLY ADSORBED CO R. JAEGER * and D. MENZEL Physik Department E 20, Institut fiir Festktirperphysik, D-8046 Garching, FR Germany
Technische
Universitci’tMiinchen,
Received 31 July 1979; accepted for publication 23 October 1979 Mass-discriminating measurements of the angular distributions of electron-stimulated ion desorption (ESDIAD) from CO adsorbed on W(100) and coadsorbed with C and 0 have been performed. The O* beams indicate normal and off-normal (by 5 to 13”) desorption which is interpreted as due to CO molecules bound in symmetric and in two types of unsymmetric bridges. Preadsorption of C suppresses the vertical state, while oxidation of the surface suppresses the off-normal states.
Surface Science 93 (1980) 84-106 0 North-Holland Publishing Company
THE INFLUENCE OF NON-RADIATIVE TRANSITIONS ON BOMBARDMENT INDUCED PHOTON EMISSION FROM Ti AND Ti OXIDE C.M. LOXTON, R.J. MacDONALD and P.J. MARTIN Department
of Physics, The Australian National University, Canberra, Australia 2601
Received 4 June 1979; accepted for publication 12 October 1979 Photon yields from Ti atoms sputtered from Ti and Ti oxide due to 55 keV Ar+ and 0; ion bombardment have been studied. Photon yields and line profiles of selected lines have also been studied as a function of background 02 exposure. An attempt has been made to correlate changes in yields and line shapes with variations of the band structure in the solid. Resonance ionization processes are shown not to contribute to the observed yield, however Auger processes cannot be excluded. Lifetime effects have a strong influence on the observed results. It is shown that the distribution of excited states produced by the ion bombardment is Boltzmannlike. We note that it is possible to interpret these results in terms of a model which assumes that the probability of excitation or ionization is exponentially dependent on the excitation or ioniration energy, without invoking electron exchange mechanisms.
Surface Science 93 (1980) 107-116 0 North-Holland Publishing Company
LASER INDUCED CHARGE TRANSFER FROM Ni TO CO ADSORBED ON (111) AND (110) SURFACES * H.W. RUDOLF and W. STEINMANN Sektion Physik der Universitlit Miinchen, Schellingstrasse 4. D-8000 Miinchen 40, Germany
Received 21 August 1979; accepted for publication 5 November 1979 Ni( 110) and (111) surfaces covered with up to one monolayer of CO were irradiated with the light of a dye laser in the photon energy range 2.0 to 3.4 eV. Two-photon photoemission was observed when the laser light was focussed. Upon defocussing a signal was measured which