The adsorption character and desorption kinetics of the weakly bound oxygen on thin iron, palladium and titanium film surfaces

• Autorzy: Lisowski W.
• Języki publikacji: EN

Abstrakty

EN

New data concerning the electrical nature of adsorption as well as the kinetics of desorption of weakly bound oxygen state on thin metal films, obtained in situ under controlled UHV conditions, are presented. The measurements of surface potential (SP) have been carried out to distinguish between elementary steps of surface processes, accompanying the formation of weakly bound oxygen states on thin Fe, Pd and Ti films at 78 and 298 K. These states appear under the oxygen pressure higher than 10(-4) Torr, following a strong chemisorption of oxygen adatoms. Both adsorption and desorption phenomena have been carried out under isothermal conditions. It has been found that weakly bound (activation energy of desorption<18 kJ/mol), positively polarized oxygen admolecules (delta(+)), are present on Fe, Pd and Ti surfaces at 78 K, covering more than 65% of the monolayer located on the top of strongly chemisorbed oxygen adatoms. Weakly bound oxygen admolecules were also observed at 298 K on thin Ti and Fe films (activation energy of desorption was the range 80-95 kJ/mol). These admolecules are licated on the top of strongly preadsorbed oxygen adatoms, forming low-coverage ((Theta=0.25), negatively polarized oxygen state (alpha(-)). The electrical nature of O2 ordering in the weakly bound oxygen layer at both temperatures has also been considered.

Słowa kluczowe

EN

adsorption; isothermal desorption; metal films; oxygen; surface potential measurements; kinetics

• Wydawca: Polskie Towarzystwo Chemiczne
• Czasopismo: Polish Journal of Chemistry
• Rocznik: 1998
• Tom: Vol. 72, nr 4
• Strony: 756--765
• Opis fizyczny: Bibliogr.22 poz., tab., wykr.

Twórcy

autor

Lisowski W.

• Institute of Physical Chemistry Polish Academy of Sciences Kasprzaka 44/52 01-224 Warszawa Poland