A very low energy electron reflection study of hydrogen adsorption on W(100) and W(110) surfaces

ASll 336

SurFace Science 175 (1986) 336-368 North-Holland, Amsterdam

A VERY LOW ENERGY ELECTRON REFLECTION STUDY OF HYDROGEN ADSORPTION ON W(100) AND W(I10) SURFACES H.-J. HERLT

a n d E. B A U E R

Phystkahsches lnstttut, Techmsche Umversttdt Clausthal, D-3392 Clausthal- Zellerfeld, Fed Rep of Germany Received 23 December 1985, accepted for pubhcatlon 26 April 1986 Expenmental results of the elastic backscattermg of electrons with energies between 0 and 20 eV from the surface systems H/W(100) and H / W ( l l 0 ) are reported and interpreted on the basis of the Darwin model On W(100) the adatom distance from the reconstructed substrate is found to be different from that on the relaxed surface Large vertmal displacements of the substrate atoms during reconstruction can be excluded. On W(ll0) the results indicate two different binding states which are occupied sequentially and wluch differ sigmficantly m their distances from the surface Work function change data are also reported for both systems

Surface Science 175 (1986) 369-384 North-Holland, Amsterdam THIN FILM FORMATION A u O N Mo(ll0) A. P A V L O V S K A

369 ON CHEMICALLY

MODIFIED

SURFACES:

a n d E. B A U E R

Phys:kahsches InstJtut, Techmsche Universltat Clausthal, D-3392 Clausthal- Zellerfeld and Sonderforschungsberewh 126, Gbttmgen-Clausthal, Fed. Rep of Germany Received 30 January 1986, accepted for publication 26 April 1986 The early stages of the formation of Au films on chemically modified Mo(ll0) surfaces were studied by Auger electron spectroscopy (AES), low energy electron diffraction (LEED), thermal desorptlon spectroscopy (TDS) and work funcuon change (A~) measurements The surfaces were modxfied by saturation with oxygen and CO and by carbunzation. Carbunzation did not suppress lnmal two-dimenstonal (2D) growth but on the oxygen-saturated surface Au grew from the very beginning in small 3D crystals, w~th oscillatory thickness dependence of the Auger signals CO showed an intermedmte behavlour It ts concluded that the bond strength and the locauon of the chenucal modifier normal to the surface Is decisive for the growth mode 385

Surface Science 175 (1986) 385-414 North-Holland, Amsterdam

VACANCY-TYPE SPUTrERED POSITRONS J. M A K I N E N , J. L A H T I N E N

DEFECT DISTRIBUTIONS NEAR ARGON AI(II0) SURFACE STUDIED BY VARIABLE.ENERGY AND MOLECULAR DYNAMICS SIMULATIONS A. V E H A N E N ,

P. H A U T O J A R V I ,

H. H U O M O ,

Laboratory of Physics, Helstnkt University of Technology, SF-02150 Espoo, Finland