Disulfide oligomer on .alpha.-FeOOH: adsorption state and photoadsorption

Abstract

A n epoxy-terminated disulfide oligomer (a,w-(2,3-epoxypropane)hexa[ l,l'-methylenedioxybis(2-thioetbane)]; EDS) in 1,1,l-trichloroethane was adsorbed with a density 2.8 times greater than that expected for EDS lying flat on a-FeOOH at 303.2 K. The EDS adsorption was interpreted by a loop-train-tail model. XPS and DRIFT spectra showed that about 15% of the sulfur atom in the monolayer was chemisorbed to form a monosulfoxide and the rest of the sulfur atoms in the train parts may interact weakly with the surfaces. The irradiation by W light promoted the EDS adsorption. This seems to relate to the formation of some oxidized sulfur species, such as a disulfoxide and a thiosulfone, which may be formed by oxidation due to holes produced by photoexcitation of an n-type semiconductor. The adsorption state and photoadsorption mechanism of EDS molecules at possible sites on a-FeOOH surfaces are discussed.

THE ADSORPTION AND BONDING OF H2S ON THE α-FeOOH(110) SURFACE

“…3 The study shows that about 15% of the sulfur atoms in the monolayer were chemisorbed to form a monosulfoxide and the rest of the sulfur atoms may interact weakly with the surfaces. The EDS adsorption may be related to the formation of sulfones.…”