J. Phys. Colloques
Volume 49, Numéro C6, Novembre 198835th International Field Emission Symposium / 35éme Symposium International d'Emission de Champ
|Page(s)||C6-249 - C6-254|
J. Phys. Colloques 49 (1988) C6-249-C6-254
THE REACTION OF CO WITH STEPPED METAL SURFACES TOWARDS THE FORMATION OF METAL-SUBCARBONYLSN. KRUSE1, J.H. BLOCK2 et G. ABEND2
1 Technisch Chemisches Laboratorium, ETH-Zentrum, CH-8092 Zürich, Switzerland
2 Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-1000 Berlin 33, F.R.G.
The interaction of CO with stepped surfaces of transition metal field emitter tips has been studied by means of Pulsed Field Desorption Mass Spectrometry (PFDMS) at temperatures T=300-700 K and pressures below p = 1.3-10-3 Pa. Areas of up to 180 atomic sites on various crystallographic surface planes of each sample were probed. A common feature in the field desorption mass spectra obtained during reaction of CO with Co, Ni, Ru, Rh or Pd is the observation of ions CO+ and Me(CO)xn+ (x = 1 up to 4, n = 1,2). The conclusion is that Mesubcarbonyls are formed in a consecutive reaction involving surface kink sites. In measurements with Fe, subcarbonyls have so far not been observed. Kinetic information about the observed reactions obtained from the dependence of the ion intensities on the desorption field strength, the field free reaction time (10-4 s to 1 s) between the field pulses and the surface temperature suggest Me(CO)x (x≥2) to be mobile surface species. Such mobile carbonyls may produce topographical changes of the surfaces.