Wj. Mitchell et al., DISSOCIATIVE CHEMISORPTION OF OXYGEN ON THE RU(001) SURFACE - SPECTROSCOPIC IDENTIFICATION OF PRECURSOR INTERMEDIATES AT LOW SURFACE TEMPERATURES, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 12(4), 1994, pp. 2250-2254
Citations number
44
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
The adsorption of oxygen on the Ru(001) surface at 30 K has been inves
tigated by high-resolution electron energy loss spectroscopy. Dissocia
tive chemisorption occurs up to the saturation atomic coverage [nu(per
pendicular-to) (Ru-O) = 595 cm-1], after which a small amount of a mol
ecularly chemisorbed peroxide species was isolated [nu(O-O) = 790 cm-1
]. After saturation of these atomic and molecularly chemisorbed states
, physically adsorbed oxygen with a vibrational frequency close to the
gas phase value of 1555 cm-1 was observed. The physically adsorbed ox
ygen was found to exhibit a resonance in the electron scattering cross
section at an electron beam energy of about 5.5 eV. Heating the surfa
ce to 55 K leads to desorption of the physically adsorbed overlayer. T
he peroxide species, on the other hand, dissociates between 100 and 45
0 K. Although the initial precursors to dissociative chemisorption wer
e not isolated, the peroxide identifies an intermediate precursor stat
e, and physically adsorbed oxygen identifies an extrinsic precursor st
ate.