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Syracuse, NY, United States

Mushtaq S.,London Metropolitan University | Steers E.B.M.,London Metropolitan University | Pickering J.C.,Imperial College London | Putyera K.,Evans Analytical Group
Journal of Analytical Atomic Spectrometry

The increasing use of mixed gases, including helium mixtures, in glow discharge mass spectrometry has led to a need to understand the resulting signal enhancements due to changes in excitation and ionization processes. To understand more fully these processes in glow discharge, we have carried out complementary optical emission spectrometry experiments. The presence of added gases in the plasma gas can cause major changes in the number density of plasma gas ions and metastable atoms and so affects the intensities of spectral lines involving & ionization processes. We report the results of an experimental investigation on the effect of Ar/He mixed plasmas on the relative emission intensities of various analyte materials including copper, iron and titanium. processes which are mainly dependent on the nature of the plasma gas and analyte material are observed and discussed. This journal is © the Partner Organisations 2014. Source

Lind A.G.,University of Florida | Rudawski N.G.,University of Florida | Vito N.J.,University of Florida | Hatem C.,Applied Materials | And 4 more authors.
Applied Physics Letters

A relationship between the electrical activation of Si in ion-implanted In0.53Ga0.47As and material microstructure after ion implantation is demonstrated. By altering specimen temperature during ion implantation to control material microstructure, it is advanced that increasing sub-amorphizing damage (point defects) from Si+ implantation results in enhanced electrical activation of Si in In0.53Ga0.47As by providing a greater number of possible sites for substitutional incorporation of Si into the crystal lattice upon subsequent annealing. © 2013 AIP Publishing LLC. Source

Leblanc D.,Becancour Silicon Inc. | Putyera K.,Evans Analytical Group
Transactions of Nonferrous Metals Society of China (English Edition)

Models establishing relationships between electrical resistivity and dopant densities of silicon wafers/bricks are not applicable for compensated-Si, such as upgraded metallurgical grade silicon UMG-Si. To date, no satisfactory theoretical model has been able to explain precisely the variety of new experimental results and observations related to compensated-Si. In this study, a new approach considering equilibrium ionisation constants according to electrolyte theory was proposed, which reproduce, for single-doped Si, Thurber's curves of charge carrier's mobilities. When more than one doping species are involved, as in compensated-Si, a numerical algorithm has to be used for solving multiple equilibrium systems. The study of such systems demonstrates a particular behaviour known from buffered solutions. Equilibrium constants were calculated from thermodynamic properties of chemical compounds, and a new general theory was proposed using available knowledge of electrochemistry (Nernst equation, Butler-Volmer equation). Considering that the silicon/dopant systems constitute a weak electrolyte solid solution, it is concluded that the electrolyte solution theory provides a good physical model and mathematical framework to get a better understanding of solar cell's behaviour. © 2011 The Nonferrous Metals Society of China. Source

Chen L.,Pacific Northwest National Laboratory | Li Z.,Pacific Northwest National Laboratory | Li Z.,Evans Analytical Group | Smith R.S.,Pacific Northwest National Laboratory | And 2 more authors.
Journal of the American Chemical Society

Understanding hydrogen formation on TiO2 surfaces is of great importance, as it could provide fundamental insight into water splitting for hydrogen production using solar energy. In this work, hydrogen formation from glycols having different numbers of methyl end-groups has been studied using temperature-programmed desorption on reduced, hydroxylated, and oxidized rutile TiO2(110) surfaces. The results from OD-labeled glycols demonstrate that gas-phase molecular hydrogen originates exclusively from glycol hydroxyl groups. The yield is controlled by a combination of glycol coverage, steric hindrance, TiO2(110) order, and the amount of subsurface charge. Combined, these results show that proximal pairs of hydroxyl-aligned glycol molecules and subsurface charge are required to maximize the yield of this redox reaction. These findings highlight the importance of geometric and electronic effects in hydrogen formation from adsorbates on TiO2(110). © 2014 American Chemical Society. Source

Shallenberger J.,Evans Analytical Group
Web Coating and Handling Conference 2013

The surfaces and interfaces of polymer films impact many performance properties including adhesion, printability, barrier performance and physical appearance. This talk will provide an overview of x-ray photoelectron spectroscopy (XPS, also known as ESCA) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). These two tools are, arguably, the most powerful analytical techniques available for probing the chemical structure of polymer surfaces and interfaces. Case studies from converter films will be discussed to demonstrate these capabilities. Copyright© (2013) by the Association of International Metallizers, Coaters and Laminators. Source

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