Chemical state

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

Chemical states of tritium formed in lithium-lead alloys by neutron irradiation

Abstract: Chemical states of tritium formed in lithium-lead alloys irradiated with neutrons were studied using a radiometric method. A scavenger technique was applied to distinguish the LiT fraction from the other species. The distribution of tritium in various chemical states depended considerably on the alloy composition, but was little affected by irradiation temperature and neutron fluence in the range studied. The experimental results could be well explained with the kinetic theory for hot atom reaction and showed some characteristics in the condensed phase.

Direct Correlation of Solar Cell Performance with Metal Impurity Distributions in Polycrystalline Silicon using Synchrotron-Based X-ray Analysis

Abstract: The work presented here directly measures metal impurity distributions and their chemical state in as-grown and fully processed polycrystalline silicon used for terrestrial-based solar cells. The goal was to determine if a correlation exists between poorly performing regions of solar cells and metal impurity distributions as well as to ascertain the chemical state of the impurities. Synchrotron-based x-ray fluorescence mapping and x-ray absorption spectroscopy, both with a spatial resolution of lμm, were used to measure impurity distributions and chemical state, respectively, in poorly performing regions of polycrystalline silicon. The Light Beam Induced Current method was used to measure minority carrier recombination in the material in order to identify poor performance regions. We have detected iron, chromium, nickel, gold and copper impurity precipitates and we have recognized a direct correlation between impurity distributions and poor performing regions in both as-grown and fully processed material. Furthermore, from x-ray absorption studies, we have initial results, indicating that the Fe in this material is in oxide form, not FeSi2,. These results provide a fundamental understanding into the efficiency-limiting factors of polycrystalline silicon solar cells as well as yielding insight for methods of solar cell improvement.

Chemical states of oxygen implanted in SUS 304 stainless steel and pure metals studied by in situ XPS using synchrotron radiation

Abstract: The chemical states of oxygen implanted in SUS304 stainless steel and pure metals (Fe,Ni,Cr) by O2+ ion bombardment have been investigated by means of X-ray photoelectron spectroscopy (XPS) using synchrotron soft X-ray. For SUS304, all of implanted oxygen is chemically combined with the constituent metals, forming metallic oxides. For pure metals, on the other hand, only a part of implanted oxygen react with the target metals. The other part of the implanted oxygen in pure metals does not react with the target, and they are inserted into the crystal lattice (we call them as “dissolved oxygen”). The ratio of “dissolved oxygen” to the reacted oxygen depends on the chemical reactivity of target metals.

Development of a WDX-μ-PIXE system for chemical state mapping

Abstract: In this paper, we have developed a wavelength dispersive X-ray spectrometer microparticle-induced X-ray emission (WDX-μ-PIXE) system combining a microbeam system with high spatial resolution and wavelength dispersive X-ray (WDX) spectrometry with high-energy resolution for chemical state mapping. A Von Hamos geometry was used for the WDX system to achieve higher detection efficiency and energy resolution. The system consists of a curved crystal and a CCD camera. The WDX system was installed in a newly developed microbeam system. The energy resolution of the WDX system was 0.67 eV for Si-Kα1 (1740 eV). Si-Kα1,2 and Si-Kβ X-ray spectra from various Si compounds were measured and chemical shifts related to chemical states were clearly observed. The system was applied to the chemical state analysis of clay particles. After elemental mapping of the clay particles using a conventional μ-PIXE system with a Si(Li) detector, particles to be analyzed were selected and analyzed sequentially with the WDX system. Si-Kβ spectra from clay particles were obtained. The microscopic spatial distribution of elements and chemical state of the clay particles were sequentially measured with high energy and spatial resolution using a microbeam.