SSIMS and TDS investigation of CO adsorption on Pd(111) during CO and O2 exposure

A724 N. NESHEV Insiitute Received

of Kinetics and Catalysis, Bulgarian Academy 16 July 1984; accepted

for publication

of Sciences, 1040 Sofia, Bulgaria

17 July 1985

Oxygen adsorption on a Mo(ll1) surface is investigated at low pressures (lo-’ to 10e5 Pa) and room temperature by Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS). In agreement with previous studies it is established that the surface is not reconstructed during adsorption and the oxygen forms no ordered structures. On the basis of kinetic and spectroscopy data, the formation of two adsorption states on the surface within 1 monolayer is established. The valence band of a clean surface is studied in detail.. An attempt is made to ascribe the peaks obtained to definite d states. The interaction between 0, and Mo(ll1) is discussed in terms of the results obtained and a comparison with the O,/W(lll) system is made.

209

Surface Science 164 (1985) 209-219 North-Holland, Amsterdam

SSIMS AND TDS INVESTIGATION DURING CO AND O2 EXPOSURE V. MATOLIN

*, S. CHANNAKHONE

OF CO ADSORPTION and E. GILLET

Laboratoire de Microscopic et Diffractions Electroniques, Faculte des Sciences et Techniques de Saint-Jerome, F- 13397 Marseille Cedex 13, France Received

14 November

1984; accepted

ON Pd(ll1)

for publication

UA 797,

19 July 1985

The CO adsorption on Pd(ll1) under the conditions of CO catalytic oxidation (i.e. at various surface temperature) has been studied using the techniques of thermal desorption spectroscopy (TDS) and static secondary ion mass spectroscopy (SSIMS). The linear relationship between the sum of ion intensity ratios C,(Pd.CO+/PdT) and CO coverage was confirmed combining the TDS and SSIMS data. The possibility of the adsorbate structure investigation by SSIMS method during catalytic reaction was demonstrated. The TDS data, obtained under catalytic conditions (without stopping CO + 0, exposure) made it possible to determine the catalytic turnover rate as a function of CO coverage.

Surface

220

Science 164 (1985) 220-234 North-Holland, Amsterdam

ANGLE-RESOLVED PHOTOEMISSION OF THE c(2 X 2) AND c(3 X 1) OXYGEN OVERLAYERS ON Fe(ll0) Y. SAKISAKA, T. KOMEDA, T. MIYANO and M. ONCHI Department

of Chemistry,

Faculty of Science, Kyoto University, Kyoto 606, Japan

S. MASUDA and Y. HARADA Department Japan

of Chemistry,

College of Arts and Sciences,

University

of Tokyo, Komaba,

Tokyo 153,