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Relative stability of ternary adsorption sites on (111) fcc and (0001) hcp transition-metal surfaces
A429 Surface Science 287/288 (1993) 946-949 North-Holland
Relative stability of ternary adsorption sites on (111) fcc and (0001) hcp transition-metal surfaces B. Piveteau a, D. Spanjaard b and M.C. Desjonqu~res a a CEA, CE Saclay, DSM, DRECAM, SRSIM, 91191 Gif-sur-Yvette Cedex, France b Laboratoire de Physique des Solides, B~timent 510, Universit~ Paris-Sud, 91405 Orsay Cedex, France Received 27 July 1992; accepted for publication 14 October 1992 In order to shed some light on the problem of crystal growth we here present a theoretical study of the relative stability of ternary adsorption sites on a close-packed surface of a hcp or fcc transition metal. We find that on Ir(111) the relative stability of the normal and fault sites varies with the nature of the adatom, which is in very good agreement with experiments: a single Ir adatom prefers the fault site, while an adatom with a larger d-band filling is more stable at a normal site. A similar calculation is carried out on Ru(0001) and predictions are made concerning the relative stability of these two adsorption sites.
Surface Science 287/288 (1993) 950-954 North-Holland
Growth of Au on Cu(001) studied by full hemispherical photoelectron diffraction D. Naumovid, J. Osterwalder, A. Stuck, P. Aebi and L. Schlapbach Institut de Physique, Universit~ de Fribourg, CH-1700 Fribourg, Switzerland Received 1 September 1992; accepted for publication 8 October 1992 Ultrathin Au films of 1 to 10 monolayers (ML) have been deposited in situ on Cu(001) at room temperature. Their structure has been investigated by X-ray photoelectron diffraction (XPD), presented as full solid angle intensity maps of the Au 4ds/2 peak, and by low energy electron diffraction. The XPD patterns change from fourfold fcc (001) at low coverage to threefold fcc (111) at high coverage. The goal of this work is to reveal the different steps of such a drastic structure transformation.
Surface Science 287/288 (1993) 955-959 North-Holland
Growth of metastable high-order commensurate overlayers of Pb on Cu(001) Wei Li and Gianfranco Vidali Department of Physics, Syracuse University, Syracuse, N Y 13244-1130, USA Received 24 August 1992; accepted for publication 1 October 1992 We studied the growth and ordering of a Pb layer deposited on Cu(001) at 150 K. Contrary to the case of adsorption of Pb at room temperature, islands readily form. These islands order in a high-order commensurate structure of symmetry ( 6v~i× 6v~)R t a n - 1(5/6). We followed the growth of these islands using atom beam scattering. From the measurement of the island diffraction peak profiles we found a power growth law for the mean island-size versus coverage. Upon increasing the coverage another high-order commensurate structure is formed, (5 × 5) R t a n - 1(3/4). All the ordered phases obtained by adsorption at low temperature are metastable.
Relative stability of ternary adsorption sites on (111) fcc and (0001) hcp transition-metal surfaces B. Piveteau a, D. Spanjaard b and M.C. Desjonqu~res a a CEA, CE Saclay, DSM, DRECAM, SRSIM, 91191 Gif-sur-Yvette Cedex, France b Laboratoire de Physique des Solides, B~timent 510, Universit~ Paris-Sud, 91405 Orsay Cedex, France Received 27 July 1992; accepted for publication 14 October 1992 In order to shed some light on the problem of crystal growth we here present a theoretical study of the relative stability of ternary adsorption sites on a close-packed surface of a hcp or fcc transition metal. We find that on Ir(111) the relative stability of the normal and fault sites varies with the nature of the adatom, which is in very good agreement with experiments: a single Ir adatom prefers the fault site, while an adatom with a larger d-band filling is more stable at a normal site. A similar calculation is carried out on Ru(0001) and predictions are made concerning the relative stability of these two adsorption sites.
Surface Science 287/288 (1993) 950-954 North-Holland
Growth of Au on Cu(001) studied by full hemispherical photoelectron diffraction D. Naumovid, J. Osterwalder, A. Stuck, P. Aebi and L. Schlapbach Institut de Physique, Universit~ de Fribourg, CH-1700 Fribourg, Switzerland Received 1 September 1992; accepted for publication 8 October 1992 Ultrathin Au films of 1 to 10 monolayers (ML) have been deposited in situ on Cu(001) at room temperature. Their structure has been investigated by X-ray photoelectron diffraction (XPD), presented as full solid angle intensity maps of the Au 4ds/2 peak, and by low energy electron diffraction. The XPD patterns change from fourfold fcc (001) at low coverage to threefold fcc (111) at high coverage. The goal of this work is to reveal the different steps of such a drastic structure transformation.
Surface Science 287/288 (1993) 955-959 North-Holland
Growth of metastable high-order commensurate overlayers of Pb on Cu(001) Wei Li and Gianfranco Vidali Department of Physics, Syracuse University, Syracuse, N Y 13244-1130, USA Received 24 August 1992; accepted for publication 1 October 1992 We studied the growth and ordering of a Pb layer deposited on Cu(001) at 150 K. Contrary to the case of adsorption of Pb at room temperature, islands readily form. These islands order in a high-order commensurate structure of symmetry ( 6v~i× 6v~)R t a n - 1(5/6). We followed the growth of these islands using atom beam scattering. From the measurement of the island diffraction peak profiles we found a power growth law for the mean island-size versus coverage. Upon increasing the coverage another high-order commensurate structure is formed, (5 × 5) R t a n - 1(3/4). All the ordered phases obtained by adsorption at low temperature are metastable.