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Chemical state
About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.
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TL;DR: In this article, the ion-beam mixing process is able to break the bonding of constituent atoms of irradiated polyimide layers and induce the formation of chemically bonded complexes linking atoms in the Cu, Al and PI layers.
Abstract: Cu (40 nm)/Al/polyimide/Si was mixed with 80 keV Ar+ and N2+ from 5.0×1015 to 15×1015 ions/cm2. Ultrasoft x-ray emission valence spectra (XES) of Cu, C, N and O excited by electron and photon radiation were used for study of chemical reactions in Cu/Al/PI/Si and PI/Si systems induced by ion beam mixing in dependence of type of ions and dose. It is found that ion beam mixing changes the chemical state of Cu atoms with respect to that of pure metal. These changes depend on the dose of ion beam bombardment and type of ions and are attributed to a formation of CuAl2O4 interfacial layer, which can be responsible for enhanced interfacial adhesion strength. On the other hand, it is shown that the shape of C Kα, N Kα and O Kα XES of ion beam mixed polyimide layer (PI/Si) is modified with ion bombardment. This means that the ion-beam mixing process is able to break the bonding of constituent atoms of irradiated PI layers and can induce the formation of chemically bonded complexes linking atoms in the Cu, Al and PI...
3 citations
TL;DR: The capability of an analysis system consisting of a low voltage scanning electron microscope, which is superior in spatial resolution and surface sensitivity, and a superconducting transition edge sensor (TES), which is under development, has been evaluated as mentioned in this paper.
Abstract: The capability of an analysis system consisting of a low voltage scanning electron microscope, which is superior in spatial resolution and surface sensitivity, and a superconducting transition edge sensor (TES), which is under development, has been evaluated. The analysis system equipped with the TES, which has a superior energy resolution by about an order of magnitude to a conventional energy dispersive x-ray spectrometer (EDS), is useful for chemical state analysis that makes use of the strength ratio of characteristic x-rays of the same series. Elemental segregation in microstructures, whose size is several tens of nanometers as for simple energy-window maps or around 10 nm as for point analysis, is also detectable. It is expected that precise distribution of minor elements, which overlap with major elements in conventional EDS spectra, and chemical state maps of specific elements can be evaluated if the data processing of spectral imaging is incorporated into the system.
3 citations
3 citations
TL;DR: In this article, the physical and chemical state of reduced Ga using in-situ X-ray absorption at the Ga K-edge was investigated, showing that reduced Ga is present in highly dispersed form without Ga nearest neighbors, probably as a monomeric hydride species coordinated to basic oxygens within zeolite channels.
Abstract: Ga species in H-ZSM5 zeolites catalyze rate-limiting dehydrogenation steps during the conversion of alkanes to aromatics. Specifically, they promote the recombinative desorption of H-adatoms as H2 and thus inhibit undesired cracking reactions. Here, we describe studies of the physical and chemical state of Ga using in-situ X-ray absorption at the Ga K-edge. Ga+3 species initially present in fresh catalysts reduce at temperatures below 770 K during hydrogen pretreatment or propane reactions. Reduced Ga is present in highly dispersed form without Ga nearest neighbors, probably as a monomeric hydride species coordinated to basic oxygens within zeolite channels. These hydride species are driven to release molecular hydrogen by the high surface hydrogen fugacities that develop during propane dehydrocyclodimerization on H-ZSM5. Reduced Ga species reoxidize to Ga+3 when samples are cooled to room temperature in flowing H2, suggesting that active forms of Ga exist only at reaction conditions. This work illustrates the critical need for in-situ techniques to establish the chemical form of catalytic sites and the misleading conclusions that can arise from the exclusive use of pre- and postreaction characterization to suggest the nature of the catatlytic sites.
3 citations
TL;DR: In this article, the effect of varied atomic compositions on the structure, electrical conductivity, thermal expansion and electrochemical performance of series compounds Ca3(Co0.9M 0.1)2O6 (M=Co, Fe, Mn, Ni) were systematically evaluated.
3 citations