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Structure and orientation of benzene and pyridine on Ir(111): Evidence for molecular distortion of benzene
A464 256
Surface Science 159 (1985) 256-264 North-Holland, Amsterdam
UHV-SEM OBSERVATIONS FORMATION ON SILICON Y. I S H I K A W A ,
N. IKEDA,
OF CLEANING PROCESS AND STEP (111) SURFACES BY ANNEALING M. KENMOCHI
a n d T. I C H I N O K A W A
Department of Applied Physics, Waseda University, 3-4-1, Ohkubo, Shinjuku-ku, Tokyo 160, Japan Received 29 October 1984; accepted for publication 19 March 1985 The cleaning process and step formation by high temperature annealing up to 1250°C on the Si(ll 1) surface are observed by an ultra-high-vacuum scanning electron microscope (UHV-SEM). The clean surface is composed of alternate planes of terraces and step bands with widths of several ~m and 1 /Lm, respectively, in the (112) direction. Both planes are inclined by about 10 ° to each other. The surface steps are not only monolayer steps, but also higher steps comprising several monolayers. Monolayer steps join to form a high step, and 70-80 steps of several monolayers high form a step band by bunching in an average distance of several hundred ~, toward the <110) direction. The step structure depends on the annealing temperature and on the angle at which the cutting plane is off from the exact (111) orientation. In several studies of high energy reflection electron microscopy under small grazing angle incidence monolayer steps were observed on the terrace, but no rough structures like the step bands and high steps could be discerned. The step structure observed by the present experiment is compared with those observed by previous workers.
Surface Science 159 (1985) 265-282 North-Holland, Amsterdam
265
STRUCTURE AND ORIENTATION OF BENZENE AND PYRIDINE ON EVIDENCE FOR MOLECULAR DISTORTION OF BENZENE
Ir(lll):
J.U. MACK,
E. B E R T E L
and F.P. NETZER
Institut ff~r Physikalische Chemie, Universiti~t Innsbruck, A-6020 lnnsbruck, Austria Received 25 January 1985; accepted for publication 9 April 1985 Angle-resolved UV photoemission (ARUPS) has been used in conjunction with electron stimulated desorption ion angular distribution (ESDIAD) to study the molecular structure and orientation of benzene and pyridine on Ir(lll). ARUPS indicates Car symmetry for the benzene adsorption complex, which is interpreted in terms of a trigonal distortion of the adsorbed molecules. For pyridine a distorted C2v symmetry is derived from ARUPS. This suggests that the pyridine molecules are adsorbed via the N atom in an upright standing geometry, with a small inclination of the ring plane with respect to the surface normal. ESDIAD specifies the tilt angle of the ring plane to - 2 0 ° from the surface normal, and reveals azimuthal preference of the inclination.
Surface Science 159 (1985) 256-264 North-Holland, Amsterdam
UHV-SEM OBSERVATIONS FORMATION ON SILICON Y. I S H I K A W A ,
N. IKEDA,
OF CLEANING PROCESS AND STEP (111) SURFACES BY ANNEALING M. KENMOCHI
a n d T. I C H I N O K A W A
Department of Applied Physics, Waseda University, 3-4-1, Ohkubo, Shinjuku-ku, Tokyo 160, Japan Received 29 October 1984; accepted for publication 19 March 1985 The cleaning process and step formation by high temperature annealing up to 1250°C on the Si(ll 1) surface are observed by an ultra-high-vacuum scanning electron microscope (UHV-SEM). The clean surface is composed of alternate planes of terraces and step bands with widths of several ~m and 1 /Lm, respectively, in the (112) direction. Both planes are inclined by about 10 ° to each other. The surface steps are not only monolayer steps, but also higher steps comprising several monolayers. Monolayer steps join to form a high step, and 70-80 steps of several monolayers high form a step band by bunching in an average distance of several hundred ~, toward the <110) direction. The step structure depends on the annealing temperature and on the angle at which the cutting plane is off from the exact (111) orientation. In several studies of high energy reflection electron microscopy under small grazing angle incidence monolayer steps were observed on the terrace, but no rough structures like the step bands and high steps could be discerned. The step structure observed by the present experiment is compared with those observed by previous workers.
Surface Science 159 (1985) 265-282 North-Holland, Amsterdam
265
STRUCTURE AND ORIENTATION OF BENZENE AND PYRIDINE ON EVIDENCE FOR MOLECULAR DISTORTION OF BENZENE
Ir(lll):
J.U. MACK,
E. B E R T E L
and F.P. NETZER
Institut ff~r Physikalische Chemie, Universiti~t Innsbruck, A-6020 lnnsbruck, Austria Received 25 January 1985; accepted for publication 9 April 1985 Angle-resolved UV photoemission (ARUPS) has been used in conjunction with electron stimulated desorption ion angular distribution (ESDIAD) to study the molecular structure and orientation of benzene and pyridine on Ir(lll). ARUPS indicates Car symmetry for the benzene adsorption complex, which is interpreted in terms of a trigonal distortion of the adsorbed molecules. For pyridine a distorted C2v symmetry is derived from ARUPS. This suggests that the pyridine molecules are adsorbed via the N atom in an upright standing geometry, with a small inclination of the ring plane with respect to the surface normal. ESDIAD specifies the tilt angle of the ring plane to - 2 0 ° from the surface normal, and reveals azimuthal preference of the inclination.