FIZIKA A 4 (1995) 2, 279-286

size 210 kB

INTERACTION OF OXYGEN AND WATER-VAPOUR WITH CLEAN AND HYDROGEN-PRECOVERED THIN IRON FILMS STUDIED BY SURFACE POTENTIAL MEASUREMENTS

WOJCIECH LISOWSKI and RYSZARD DU\' S
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland

Received 7 April 1995
Revised manuscript received 31 May 1995

Oxygen adsorption on both clean and hydrogen-precovered thin Fe films has been investigated by measuring the surface potential (SP), gas phase composition and the total gas pressure at 298 K. The results were supplemented by SP studies of water-vapour adsorption on clean and oxygen-precovered thin iron films. Oxygen interaction with Fe film pre-exposed to water-vapour has also been studied at 298 K. It has been observed that only a small part of the initially deposited hydrogen desorbs due to the competitive adsorption of oxygen. Most of the hydrogen adspecies remain on the surface diminishing the amount of adsorbed oxygen and affecting the electrical character of the oxygen adsorbate. Water adsorbs dissociatively on clean Fe film at 298 K, decreasing the SP. Precovering Fe film with O2 at 298 K prevents the decomposition of water. The amount of oxygen consumed is only slightly diminished by water preadsorbed on clean Fe film at 298 K.

UDC 538.971
PACS 68.45.Da
Copyright by The Croatian Physical Society
For problems or questions please contact fizika@fizika.hfd.hr