Mossbauer Investigation into the Reactions of Laser-evaporated Iron with Solid Oxygen at Low Temperatures

Laser-evaporated iron was deposited onto solid oxygen at 20 K to produce stratified samples consisting of Fe and 02 layers. The Mossbauer spectra of these samples were acquired in order too investigate their oxidation states and chemical properties. The reaction produced the trivalent iron oxide particles whose size varied depending on the amount of Fe atoms deposited on the solid oxygen. Samples which had smaller amounts of Fe produced smaller iron oxide particles having superparamagnetism. When the sample was annealed at 293 K, the size of the iron oxide particles became larger due to aggregation. The sample with the thickest Fe-layer (180 nm) had a pure a-Fe layer above the iron oxide layer, and the divalent iron oxide was formed after annealing at 293 K.