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Interpretation of AFM images: the graphite surface with a diamond tip
A579 Extensive data sets of spin-polarized low energy electron diffraction (SPLEED) rotation curves from the clean W(001)-(1 × 1) and hydrogen-saturated W(001)-2H(1 × 1) surfaces are presented. These represent the first simultaneous LEED measurements of two components of the electron spin polarization and diffracted intensity on any system. These measurements should be more sensitive to the disorder of the surface layer of clean W(001)-(1 × 1) than traditional LEED I - V curves at normal incidence for three reasons: the large scattering angles enhance intralayer scattering relative to interlayer scattering; electron spin polarization measurements are particularly sensitive to intensity minima where diffuse scattering from disorder is relatively important; and the data set is a comparative study of ordered and disordered surfaces. The data are in qualitative agreement with a smaller surface layer contraction and a greater degree of order on the hydrogen-saturated surface compared to the clean surface. These results suggest that detailed SPLEED calculations are justified to test and quantify these indications.
Surface Science 291 (1993) 429-438 North-Holland
HREELS study on CO adsorbed on clean, nitrided and oxidized Fe/Ru(O01) surfaces Takehiko Sasaki, Tetsuya Aruga and Yasuhiro Iwasawa * Department of Chemistry, Faculty of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan Received 26 November 1992; accepted for publication 22 March 1993 CO adsorption on as-deposited, nitrided and oxidized Fe/Ru(001) surfaces was investigated using high resolution electron energy loss spectroscopy (HREELS), temperature programmed desorption (TPD), Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). The behaviour of CO on Fe/Ru(001) was compared to that on low Miller index planes of an Fe single crystal. It was found that the as-deposited Fe(1 ML)/Ru(001) surface resembles the Fe(ll0) surface. A single CO species with a v(C-O) of 1860-1990 cm-1 was found on the as-deposited surface. A new molecular adsorption state appeared on the annealed Fe/Ru(001) surface. This species has a higher C - O stretching frequency and a higher desorption temperature than the other species. The effects of nitridation and oxidation of Fe/Ru(001) on CO adsorption were also investigated.
Surface Science 291 (1993) 439-450 North-Holland
Interpretation of AFM images: the graphite surface with a diamond tip H. Tang, C. Joachim and J. Devillers CEMES-LOE, 29 rue Jeanne Marvig, BP 4347, 31055 Toulouse Cedex, France Received 9 December 1992; accepted for publication 8 April 1993 Constant force AFM images of the graphite surface using a diamond tip are calculated from a standard molecular mechanics force field. It is shown that there is no need for an asymmetric tip apex nor for a graphite flake under the apex to reproduce the experimental images. A good orientation of the tip apex and a good choice of the force applied is enough to evolute from a trigonal to a honeycomb AFM apparent surface structure for graphite.
Surface Science 291 (1993) 451-459 North-Holland
Aluminum-ion sputtering from A1 surfaces with very-low-energy ions Michio Okada and Yoshitada Murata The Institute for Solid State Physics, The University of Tokyo, 7-22-1, Roppongi, Minato-ku, Tokyo 106, Japan Received 19 February 1993; accepted for publication 25 March 1993 Sputtering of AI + for N~-, N+, and Ne + incidence was observed at a threshold energy of ~ 20 eV. The polar-angle distribution of the sputtered AI + ions gives almost the same lobe position at different angles of incidence. In N + and Ne ÷ incidence on the AI(lll) surface, a sharp structure which correlates with the crystal structure, was observed in the angular distribution of the sputtered AI + ions. In ion incidence on the open surface of AI(ll0), chemical interaction between a projectile and the target material plays an important role in the sputtering process. The mechanisms of ion sputtering induced by very-low-energy ions ( < 200 eV) are discussed.
Surface Science 291 (1993) 429-438 North-Holland
HREELS study on CO adsorbed on clean, nitrided and oxidized Fe/Ru(O01) surfaces Takehiko Sasaki, Tetsuya Aruga and Yasuhiro Iwasawa * Department of Chemistry, Faculty of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan Received 26 November 1992; accepted for publication 22 March 1993 CO adsorption on as-deposited, nitrided and oxidized Fe/Ru(001) surfaces was investigated using high resolution electron energy loss spectroscopy (HREELS), temperature programmed desorption (TPD), Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). The behaviour of CO on Fe/Ru(001) was compared to that on low Miller index planes of an Fe single crystal. It was found that the as-deposited Fe(1 ML)/Ru(001) surface resembles the Fe(ll0) surface. A single CO species with a v(C-O) of 1860-1990 cm-1 was found on the as-deposited surface. A new molecular adsorption state appeared on the annealed Fe/Ru(001) surface. This species has a higher C - O stretching frequency and a higher desorption temperature than the other species. The effects of nitridation and oxidation of Fe/Ru(001) on CO adsorption were also investigated.
Surface Science 291 (1993) 439-450 North-Holland
Interpretation of AFM images: the graphite surface with a diamond tip H. Tang, C. Joachim and J. Devillers CEMES-LOE, 29 rue Jeanne Marvig, BP 4347, 31055 Toulouse Cedex, France Received 9 December 1992; accepted for publication 8 April 1993 Constant force AFM images of the graphite surface using a diamond tip are calculated from a standard molecular mechanics force field. It is shown that there is no need for an asymmetric tip apex nor for a graphite flake under the apex to reproduce the experimental images. A good orientation of the tip apex and a good choice of the force applied is enough to evolute from a trigonal to a honeycomb AFM apparent surface structure for graphite.
Surface Science 291 (1993) 451-459 North-Holland
Aluminum-ion sputtering from A1 surfaces with very-low-energy ions Michio Okada and Yoshitada Murata The Institute for Solid State Physics, The University of Tokyo, 7-22-1, Roppongi, Minato-ku, Tokyo 106, Japan Received 19 February 1993; accepted for publication 25 March 1993 Sputtering of AI + for N~-, N+, and Ne + incidence was observed at a threshold energy of ~ 20 eV. The polar-angle distribution of the sputtered AI + ions gives almost the same lobe position at different angles of incidence. In N + and Ne ÷ incidence on the AI(lll) surface, a sharp structure which correlates with the crystal structure, was observed in the angular distribution of the sputtered AI + ions. In ion incidence on the open surface of AI(ll0), chemical interaction between a projectile and the target material plays an important role in the sputtering process. The mechanisms of ion sputtering induced by very-low-energy ions ( < 200 eV) are discussed.