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Chemisorption and initial oxidation of Ni(110): AES, ELS and work function measurements
A66 Surface Science 92 (1980) 636 666 © North-Holland Publishing Company
CHEMISORPTION AND INITIAL OXIDATION OF Ni(110): AES, ELS AND WORK FUNCTION MEASUREMENTS C. B E N N D O R F , B. E G E R T , C. NOBL, H. S E I D E L and F. T H I E M E
Institut ffir Physikalisehe Chemie der Universitdt Hamburg, Loufgraben 24, D-2000 Hamburg 13, Germany Received 5 July 1979; accepted for publication 17 September 1979
The interaction of oxygen with Ni(110) surfaces was investigated from 85 to 800 K by AES, ELS, TDS and work function changes (A¢). At T = 300 K three different phases of oxygen bonding are observed: (1) Chemisorption of oxygen up to 0.6 0.8 L accompanied by an increase of work function and a kinetic energy shift of the O(KLL) Auger spectra (AE = -1.1 eV). (2) A rearrangement of the chemisorption layer and incorporation of oxygen into the Ni sublayer associated with further oxygen uptake, characterized by a decrease of A¢ per adsorbed oxygen atom. (3) Nucleation and island growth of NiO indicated by a decrease of ~ , shifts of the oxygen and Ni Auger transitions to lower kinetic energy and drastic changes in ELS and AES line shape. Low temperature adsorption experiments indicate the existence of a molecular oxygen species - marked in TDS by a partial desorption of oxygen at 250 K - and characterized by the electron spectroscopic investigations and Aq~measurements. Surface Science 92 (1980) 667-680 © North-Holland Publishing Company
EQUILIBRIUM CONFIGURATIONS OF COMMENSURATE ADSORBED MONOLAYERS: ARGON ON GRAPHITE * C.R. F U S E L I E R , J.C. R A I C H and N.S. G I L L I S
Colorado State University, Fort Collins, Colorado 80523, USA Received 25 June 1979; accepted for pubfication 1 October 1979 The equilibrium orientations and lattice constants of monolayer argon adsorbed on graphite are calculated for commensurate lattice structures. A procedure to calculate the monolayersubstrate interaction energy is developed. The equilibrium configuration at a given temperature is determined by minimizing the free energy of the monolayer-substrate system, which is calculated in the quasi-harmonic approximation. The relationship between the orientation of the monolayer relative to the substrate and the monolayer lattice constant for commensurate lattices is found to follow quite closely the relationship determined for incommensurate phases and is in agreement with recent LEED data for argon adsorbed on graphite.
Surface Science 92 (1980) 681-692 © North-Holland Publishing Company
GOLD ON SILICON SURFACES M. K U I S L and E. S A S S E
A E G - Telefunken, Nachrichten- und Verkehrstechnik A G, Forschungsinstitut, D- 7900 Ulm, Germany Received 26 July 1979; accepted for publication 28 September 1979 With the aid of tracer techniques it is shown that all known cleaning solutions for gold on
CHEMISORPTION AND INITIAL OXIDATION OF Ni(110): AES, ELS AND WORK FUNCTION MEASUREMENTS C. B E N N D O R F , B. E G E R T , C. NOBL, H. S E I D E L and F. T H I E M E
Institut ffir Physikalisehe Chemie der Universitdt Hamburg, Loufgraben 24, D-2000 Hamburg 13, Germany Received 5 July 1979; accepted for publication 17 September 1979
The interaction of oxygen with Ni(110) surfaces was investigated from 85 to 800 K by AES, ELS, TDS and work function changes (A¢). At T = 300 K three different phases of oxygen bonding are observed: (1) Chemisorption of oxygen up to 0.6 0.8 L accompanied by an increase of work function and a kinetic energy shift of the O(KLL) Auger spectra (AE = -1.1 eV). (2) A rearrangement of the chemisorption layer and incorporation of oxygen into the Ni sublayer associated with further oxygen uptake, characterized by a decrease of A¢ per adsorbed oxygen atom. (3) Nucleation and island growth of NiO indicated by a decrease of ~ , shifts of the oxygen and Ni Auger transitions to lower kinetic energy and drastic changes in ELS and AES line shape. Low temperature adsorption experiments indicate the existence of a molecular oxygen species - marked in TDS by a partial desorption of oxygen at 250 K - and characterized by the electron spectroscopic investigations and Aq~measurements. Surface Science 92 (1980) 667-680 © North-Holland Publishing Company
EQUILIBRIUM CONFIGURATIONS OF COMMENSURATE ADSORBED MONOLAYERS: ARGON ON GRAPHITE * C.R. F U S E L I E R , J.C. R A I C H and N.S. G I L L I S
Colorado State University, Fort Collins, Colorado 80523, USA Received 25 June 1979; accepted for pubfication 1 October 1979 The equilibrium orientations and lattice constants of monolayer argon adsorbed on graphite are calculated for commensurate lattice structures. A procedure to calculate the monolayersubstrate interaction energy is developed. The equilibrium configuration at a given temperature is determined by minimizing the free energy of the monolayer-substrate system, which is calculated in the quasi-harmonic approximation. The relationship between the orientation of the monolayer relative to the substrate and the monolayer lattice constant for commensurate lattices is found to follow quite closely the relationship determined for incommensurate phases and is in agreement with recent LEED data for argon adsorbed on graphite.
Surface Science 92 (1980) 681-692 © North-Holland Publishing Company
GOLD ON SILICON SURFACES M. K U I S L and E. S A S S E
A E G - Telefunken, Nachrichten- und Verkehrstechnik A G, Forschungsinstitut, D- 7900 Ulm, Germany Received 26 July 1979; accepted for publication 28 September 1979 With the aid of tracer techniques it is shown that all known cleaning solutions for gold on