Chemical state

About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.

In-Depth Profiles of Oxide Films on GaAs Studied by XPS

Abstract: Quantitative depth profiles of chemical composition of the thermal and the anodic oxide of GaAs have been studied by XPS in conjunction with argon ion sputtering. By analyzing the XPS spectra with taking account of the sputtering effects, both the amount and the chemical state of each elemental species in the oxides were obtained. In the thermal oxidation below 530°C in air, Ga2O3 was produced as a primary product and both the amounts of the evaporated-As and the accumulated-As increased with increasing oxide thickness. XPS spectra from the thermal oxides grown at 900°C in air or grown with As at ~530°C suggested that the products contained GaAsO4. The anodic oxidation resulted in films that had an As2O3/Ga2O3 ratio of about 1. The widths of the transition region between the ~500 A thick oxide and GaAs were about 70 A for the anodic oxides and 200 A for the thermal oxides.

Sibunit-based catalytic materials for the deep oxidation of organic ecotoxicants in aqueous solution: I. Surface properties of the oxidized sibunit samples

Abstract: This article presents the first systematic study of the effect of oxidation under various conditions on the surface composition and catalytic properties of a carbon material of the Sibunit family (which is promising for oxidative treatment of industrial wastewater) in deep oxidation of organic ecotoxicants in aqueous solution. Modification of the surface properties and texture of Sibunit-4 by various oxidative treatment procedures using nitric acid, sodium hypochlorite, hydrogen peroxide, or oxygen as the oxidant is reported. The chemical state of the surface of oxidized Sibunit and its texture have been investigated by a combination of physical and chemical methods (XPS, acid-base titration with bases differing in strength, pH slurry measurements, determination of pH at the point of zero charge, and low-temperature N2 adsorption). By using different oxidation procedures, it is possible to obtain oxidized Sibunit samples with variable concentrations and natures of oxygen-containing surface groups.