t~4 Surface Science 251/252 !i 991 ) 64 72 North-Hollan,.i Characterization of new materials by surface-sensitive techniques Rodolfo Miranda Departamento de Fisica de la Materia Condensada, Universidad Autbnoma de Madrid, Cantoblanco, 28049 Madrid, Spare Received 1 October 1990; accepted for publication 23 Januar 3 1991 Artificial materials with custom-designed properties are becoming a reality driven by the development of UHV techniques for growing and controlling layered structures. Surfaces and interfaces play an important role in their behaviour and surface-sensitive techniques are increasingly used to characterize the grown materials. Three recent examples will be discussed to illustrate this tendency. Surface Science 251/252 (1991) 73-77 73 North-Holland Characterization of supported mixed-oxide electrocatalysts by ion-beam techniques G. Battaglin Unith del Consorzio Interuniversitario per la Fisica della Materia, Dipartimento di Chimica Fisica dell'Universitfi, Calle Larga S. Marta 2137, 1-30123 Venezia, Italy A. De Battisti, A. Barbieri, A. Giatti and A. Marchi Dipartimento di Chimica dell'Universitfi e Centro di Studio sulla Fotoehimica e Reattivit~t degli Stati Eccitati C.C., via L. Borsari 46, 1-44100 Ferrara, Italy Received 1 October 1990; accepted for publication 20 December 1990 Injection and ejection of D + and Li + ions in thermally prepared Ir-Ti mixed oxide films have been followed by means of nuclear reaction analysis. Tests were carried out after the application of a potential that allows the maximum cation uptake and under conditions that correspond to the minimum cation uptake. Results were in good agreement with calculations based on the amount of charge exchanged by the electrodes in electrochemical experiments. Rutherford backscattering spectrometry has been used as a complementary method to study the composition profile. Interpretation of the results has been attempted in terms of local microstructural features. 78 Surface Science 251/252 (1991) 78-81 North-Holland NMR experiments on Li adsorbed on a Si(lll) surface J. Chrost and D. Fick Phihpps-Universitiit, Fachbereich Physik and Wissenschaftliches Zentrum fiir Materialwissenschaften, W-3550 Marburg Germany Received 1 October 1990; accepted for publication on 3 January 1991 The coverage dependence of the electric field gradient normal to the surface and the change in work function was measured for 6Li adsorbed on a Si(111) surface in addition to thermal desorption spectra. A distinct feature at a coverage of about 0.05 of a monolayer was observed in all measurements. The increase of the positive electric field gradient at this coverage indicates strongly that this feature is connected with a change in binding geometry of the adsorbed Li atoms.

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Page 1: Characterization of new materials by surface-sensitive techniques

t~4 Surface Science 251/252 !i 991 ) 64 72 North-Hollan,.i

Characterization of new materials by surface-sensitive techniques Rodolfo Miranda Departamento de Fisica de la Materia Condensada, Universidad Autbnoma de Madrid, Cantoblanco, 28049 Madrid, Spare

Received 1 October 1990; accepted for publication 23 Januar 3 1991

Artificial materials with custom-designed properties are becoming a reality driven by the development of UHV techniques for growing and controlling layered structures. Surfaces and interfaces play an important role in their behaviour and surface-sensitive techniques are increasingly used to characterize the grown materials. Three recent examples will be discussed to illustrate this tendency.

Surface Science 251/252 (1991) 73-77 73 North-Holland

Characterization of supported mixed-oxide electrocatalysts by ion-beam techniques G. Battaglin Unith del Consorzio Interuniversitario per la Fisica della Materia, Dipartimento di Chimica Fisica dell'Universitfi, Calle Larga S. Marta 2137, 1-30123 Venezia, Italy

A. De Battisti, A. Barbieri, A. Giatti and A. Marchi Dipartimento di Chimica dell'Universitfi e Centro di Studio sulla Fotoehimica e Reattivit~t degli Stati Eccitati C.C., via L. Borsari 46,

1-44100 Ferrara, Italy

Received 1 October 1990; accepted for publication 20 December 1990

Injection and ejection of D + and Li + ions in thermally prepared Ir-Ti mixed oxide films have been followed by means of nuclear reaction analysis. Tests were carried out after the application of a potential that allows the maximum cation uptake and under conditions that correspond to the minimum cation uptake. Results were in good agreement with calculations based on the amount of charge exchanged by the electrodes in electrochemical experiments. Rutherford backscattering spectrometry has been used as a complementary method to study the composition profile. Interpretation of the results has been attempted in terms of local microstructural features.

78 Surface Science 251/252 (1991) 78-81 North-Holland

NMR experiments on Li adsorbed on a Si( l l l ) surface J. Chrost and D. Fick Phihpps-Universitiit, Fachbereich Physik and Wissenschaftliches Zentrum fiir Materialwissenschaften, W-3550 Marburg Germany

Received 1 October 1990; accepted for publication on 3 January 1991

The coverage dependence of the electric field gradient normal to the surface and the change in work function was measured for 6Li adsorbed on a Si(111) surface in addition to thermal desorption spectra. A distinct feature at a coverage of about 0.05 of a monolayer was observed in all measurements. The increase of the positive electric field gradient at this coverage indicates strongly that this feature is connected with a change in binding geometry of the adsorbed Li atoms.