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Microcalorimetric and EGA study of germanium surfaces interacting with different gases
Author(s) -
Stradella Luigi
Publication year - 1991
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740171004
Subject(s) - chemisorption , chemistry , carbon monoxide , hydrogen , dissociation (chemistry) , vapours , desorption , adsorption , inorganic chemistry , analytical chemistry (journal) , ammonia , germanium , atmospheric temperature range , catalysis , organic chemistry , biology , neuroscience , silicon , physics , meteorology
An investigation of the adsorption of several vapours and gases (ammonia, water hydrogen, carbon dioxide, oxygen, carbon monoxide, nitrogen, dinitrogen oxide, propene) on polycrystalline germanium has been carried out at 305 K, in the pressure range between 1 × 10 −4 Pa and 20 kPa, using a Tian‐Calvet microcalorimeter. Water, ammonia, hydrogen and carbon dioxide apart, the adsorption is physical and fully reversible. The Calometric data suggest a dissociative chemisorption for hydrogen and a strong coordinative bond of water and ammonia with more active surface sites. Evolved gas analysis experiments have been performed on the same sample in the range 300–1000 K, focusing on the H 2 –Ge, H 2 O–Ge and N 2 O–Ge systems. Temperature‐programmed mass spectra desorption mass spectra indicate that 700 K is the optimum temperature for H 2 O dissociation, while at 550 K there is a maximum in H 2 chemisorption; as with the decomposition of N 2 O, a strong adsorption on the semiconductor of all the species present at the interface strongly interface with the chemical equilibrium.