Showing papers on "Chemical state published in 1978"
••
TL;DR: In this paper, the authors used Auger spectroscopy as a probe of local chemical environment both in the gas and condensed phases using a systematically chosen series of molecules [H2O, CH3OH, (CH3)2O), CH4, C2H2, and C2C2].
Abstract: We have used Auger spectroscopy as a probe of local chemical environment both in the gas and condensed phases using a systematically chosen series of molecules [H2O, CH3OH, (CH3)2O, CH4, C2H4, and C2H2]. For the series of gas phase molecules, H2O, CH3OH, (CH3)2O, and CH4, where oxygen and carbon are, respectively, in similar bonding arrangements, characteristic fingerprint spectra (methanelike for C and waterlike for O) are shown to result. Additional fine structure, which is dependent on the specific molecular environment, appears on the spectra. In contrast, dramatic differences are observed for the series CH4, C2H2, and C2H4 in which major differences in hybridization exist at the carbon site. H2O, CH3OH, and (CH3)2O were studied both in the gas phase (electron excited) and in the condensed phase (x‐ray excited). The O(KVV) (K level–valence–valence transition) and C(KVV) spectra are shown to be similar when comparing the gas–solid results only if the multilayer spectra are properly corrected for electr...
164 citations
••
TL;DR: In this article, the chemical state and environment of palladium supported on silica, titania, and alumina have been studied by uv-visible and X-ray photoelectron spectroscopy.
105 citations
••
TL;DR: In this paper, the use of Auger peak shape analysis to obtain depth profiles of chemical state is illustrated by the detection of thin silicide layers at the metal/Si interface in as-deposited samples.
Abstract: We discuss the use of Auger electron spectroscopy to obtain chemical state information about the transition‐metal/Si and silicide/Si interfaces. Characteristic Si L2,3VV Auger spectra for silicides of nine different transition metals are presented and analyzed in terms of chemical bonding in the compounds. The use of Auger peak shape analysis to obtain depth profiles of chemical state is illustrated by the detection of thin silicide layers at the metal/Si interface in as‐deposited samples. The possibility of chemical state changes induced by inert gas ion bombardment is discussed and this effect is proposed to explain almost identical Si LVV peak shapes observed for different silicides of a particular transition metal. Pd2Si is shown to be stable against bombardment‐induced bonding changes, and for this system sequential deposition studies of Pd on Si yield basically the same information as does sputter profiling.
97 citations
••
TL;DR: In this article, a chemical state of silicon different from that of the pure bulk silicon or silicon in SiO2, using Auger electron spectroscopy, was observed, for the first time, in the E N (E) spectra.
Abstract: We have observed, for the first time, a chemical state of silicon different from that of the pure bulk silicon or silicon in SiO2, using Auger electron spectroscopy. In the E N (E) spectra this state gives a major transition at 83.3 eV compared to 90.3 eV for bulk Si and 74.2 eV for SiO2. We have observed this state both at the Si/SiO2 interface of MOS oxide structures during sputter profiling and for thin native oxides without sputtering. The state is difficult to see in the dE N (E)/dE spectra due to the presence of the sharp edge of the free silicon peak at 92 eV which tends to mask it.
69 citations
••
TL;DR: In this paper, the XPS spectra of the valence-band region are investigated and chalcogen s and p and noble-metal d bands are clearly identified.
47 citations
••
TL;DR: In this paper, the chemical composition of the thermal and anodic oxide of GaAs has been studied by XPS in conjunction with argon ion sputtering, and both the amount and the chemical state of each elemental species in the oxides were obtained.
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.
21 citations
••
11 citations
••
TL;DR: In this article, the chemical states of so-called silicon monoxide, powder and evaporated films, were studied by fluorescent X-ray spectroscopy (FXS), Xray photoelectron spectrogrammy (XPS) and Auger electron spectrograph (AES).
Abstract: Chemical states of so-called silicon monoxide, powder and evaporated films, were studied by fluorescent X-ray spectroscopy(FXS), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy(AES). Si Kα and Kβ spectra show the existence of small amounts of SiOx(0
3 citations
••
TL;DR: In this paper, the bonding and chemical state of binary As-S glasses were investigated by determining the SKβ spectra with a vacuum 2-crystal X-ray spectrometer equipped with Ge(ll1) crystal analyzers.
Abstract: The bonding and chemical state of sulfur in binary As-S glasses were investigated by determining the SKβ spectra with a vacuum 2-crystal X-ray spectrometer equipped with Ge(ll1) crystal analyzers. For glasses with sulfur contents 60 at.%, the spectra became progressively similar to that of elemental sulfur with increasing sulfur content. It was found that S-S bonding occurs in the high-sulfur glasses.
2 citations
••
TL;DR: In this article, the authors used a gas chromatographic column to estimate the amount of desorbed 0 2 from the surface of irradiated ZnO at 25,100, 200 and 300°C.
Abstract: Direct evidence for this type of chemical change was obtained from the following experiments: Ten g of a dry sample of ZnO (BDH, 200 mesh) with adsorbed oxygen was placed in a glass sparger and the air in it was removed by a continuous flow of N2 at a rate of 60 ml per min. The sample was then contained in an N2 atmosphere and irradiated by gamma rays from a 6 0 Co source to the desired dose. The dose was measured by Fricke's dosimetry at room temperature (25 °C). After irradiation the sample was swept with a flowing N2 carrier gas which was allowed to flow through a gas chromatographic column. The 0 2 desorbed due to the irradiation was estimated quantitatively by gas chromatography using a sensitive detector [2]. The sample was then enclosed in an N2 atmosphere and the temperature was rapidly raised from 25 to 100°C and maintained at 100°C for a period of one hour. The N2 gas containing the 0 2 desorbed at 100°C was analyzed as described above, and the amount of 0 2 was estimated. The same sample, still was again enclosed in an N2 atmosphere and was further heated from 100 to 200 and the analysis for 0 2 was repeated. After one hour the procedure was repeated after raising the temperature to 300 °C and the amount of desorbed 0 2 was estimated as before. In this way the desorbed 0 2 from the surface of irradiated ZnO was estimated at 25,100, 200 and 300°C. The same procedure was adopted for the Fig. 1. Changes in the peaks of 0 2 desorbed at (A) 100, (B) 200 and (C) 300°C from the surface of the gamma irradiated ZnO