Chemical state

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

Surface development of an aluminum brazing sheet during heating studied by XPEEM and XPS

Abstract: X-ray photoelectron emission microscopy (XPEEM) was used in combination with other microscopic and spectroscopic techniques to follow the surface development of an aluminum brazing sheet during heating The studied aluminum alloy sheet is a composite material designed for vacuum brazing Its surface is covered with a native aluminum oxide film Changes in the chemical state of the alloying elements and the composition of the surface layer were detected during heating to the melting temperature It was found that Mg segregates to the surface upon heating, and the measurements indicate the formation of magnesium aluminate During the heating the aluminum oxide as well as the silicon is observed to disappear from the surface Our measurements is in agreement with previous studies observing a break-up of the oxide and the outflow of the braze cladding onto the surface, a process assisted by the Mg segregation and reaction with surface oxygen This study also demonstrates how XPEEM can be utilized to study complex industrial materials

Chemical State Mapping of Amorphous Carbon Films by Soft X-ray Emission Spectroscopy

Abstract: Soft X-ray emissions, which originate from electronic transitions from valence bands (bonding electron states) to inner-shell electron levels, inform us energy states of bonding electrons if those energies are analyzed with an energy resolution better than 1 eV. Thus, soft-X-ray emission spectroscopy (SXES) based on electron microscopy should be a hopeful method to evaluate bonding states of identified small specimen areas. SXES can apply to metal, semiconductor and insulator materials under a conventional vacuum condition of electron microscopes. One drawback is its low detection efficiency. Then, a commercial SXES spectrometer, which was composed of varied line spacing (aberration corrected) gratings and an area detector, was designed as an attachment for EPMA/SEM [1], which can use a larger probe current than that of TEM. As EPMA/SEM are operated at a lower accelerating voltage than that of TEM, bonding states of irradiation sensitive materials can be investigated. Here, SXES imaging of chemical state mapping of carbon atoms of amorphous carbon nitride (a-CNx) films and diamond like carbon (DLC) films are presented [2,5].

Studies on the chemical and colloidal nature of Pu(IV) polymer

Abstract: From tweniy-fourth congress of the International Union of Pure and Applied Chemistry; Hamburg, F. R. Germany (3 Sep 1973). Spectrophotometric, x- ray, electron diffraction, and electron microscopy studies of plutonium polymer are reported. Results indicate that the polymer consists of very small discrete particles, which can be either amorphous or crystalline, and which can be colloidally dispersed in a suitable medium such as ddlute HCl or HNO/sub 3/. Results also indicate that a monomeric Pu(IV) hydroxide species is not formed during initial precipitation as has been previously reported, but instead small crystallites of hydrated PuO/sub 2/. (JGB)