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Show ppmw As, at the Department of Chemistry, University of Utah. This study analyzed that flyash using Electron Scanning for Chemical Analysis (ESCA) technique. The technique is overviewed here along with the results of analysis, and the most salient calculations. All data provided here are from experiments performed and reported by Beebe [3]. 3.1. Overview of the ESCA Technique The ES CA technique depends upon measuring the binding energy of electrons; and it can be used to determine precisely: 1) oxidation state of a given compound and 2) where sufficient data exist, the specific compound in question. In the performance of ESCA analysis, a sample is pressed into a pellet and then inserted into a UHV chamber. The apparatus uses Mg K-alpha radiation to irradiate the sample, producing core level photoelectrons whose kinetic energy is measured by an electron spectrometer interfaced to a computer. Atoms in different oxidation states exhibit slight shifts in the binding energy of these electrons, enabling an analysis of the distribution of oxidation states. U sing data available in the literature, both oxidation states and compounds can be identified for some compounds. Quantifying the binding energy becomes the key to ESCA analysis. Binding energies for various arsenic compounds are shown in Table VIll. Note that, for binding energies <about 42 electron volts (eV), the arsenic exists in an oxidation state of -3. For binding energies of about 42 - 45 eV, the oxidation state is +3. For binding energies of >about 45 eV, the oxidation state is +5. As a practical matter, the instrument reports kinetic energy. Therefore the calculation of binding energy is accomplished by the following equation: 1253.6 - KE = BE ( 1) Where KE is kinetic energy and BE is binding energy. As a practical matter, known standards become essential, because equation #1 must be corrected for charging effects. Therefore the equation expands to: 1253.6 - KE - CFce = BE (2) Where CFce is the correction factor for charging effects. ESCA is considered to have differentiating capability up to 0.2 e V. 3.2. University of Utah Experiments The University of Utah experiments included two preliminary runs and a subsequent, defmitive, run. The two preliminary runs, made on the same sample, utilized the alumina peak within the flyash as the means of calibration. Alumina (Al~03) has a known binding energy of 74.7 eVe The defmitive run was made where the University of Utah researchers spiked the sample with high doses of potassium chloride (KCl). The KCI has two peaks: a lOP peak with a binding energy of 17 e V (+/- 0.5 e V) and a lOS binding energy of 33 e V (+/- 0.5 e V). The use of KCI spiking permitted calculating the binding energy for the arsenic contained in the flyash from |