Papers by Keyword: Mass Spectroscopy

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Authors: Brenda L. VanMil, Kok Keong Lew, Rachael L. Myers-Ward, Ronald T. Holm, D. Kurt Gaskill, Charles R. Eddy
Abstract: Real-time analysis of downstream nitrogen process-gas flows during 4H-SiC growth is reported. A Hiden Analytical HPR-20 quadrupole mass-spectrometer (QMS) was used to measure the process gas composition in the gas-stream of a hot-wall chemical vapor deposition (CVD) reactor. Using the 28 amu peak, it was found that the nitrogen partial pressure measured by the mass spectrometer directly correlates to the expected partial pressure of nitrogen in the process cell based on input flows. Two staircase doping samples were grown to track doping variations. The nitrogen mass flow was varied and corresponded to doping levels ranging from 1x1015 cm-3 to 8x1018 cm-3. Electron and nitrogen concentrations in the epilayers were measured by capacitancevoltage (CV) profiling and secondary ion mass spectrometry (SIMS), respectively. These efforts show real-time QMS monitoring is effective during growth for determining relative changes in nitrogen concentration in the gas flow, and thus, the level of nitrogen incorporation into the growing layer.
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Authors: M.A. Jiménez Gómez, Mauricio Garza Castañón, O.V. Kharissova, B.I. Kharisov, U. Ortiz Méndez
Abstract: 1-methyl-2-phenylfulleropyrrolidine (1), 1-methyl-2-(4-(1-piperidyl)-phenyl)-fulleropyrrolidine (2), 1-methyl-2-(4-fluorophenyl)-fulleropyrrolidine (3) and 1-methyl-2-(3-hydroxy-2-naphtyl)-3,4-fulleropyrrolidine (4) were synthesized by Prato reaction and characterized in the reaction mixture by UV-Vis spectroscopy and matrix assisted laser desorption ionization (MALDI). A comparison of theoretical and experimental UV spectra was carried out.
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Authors: G. Leniec, Slawomir M. Kaczmarek, J. Typek, Beata Kołodziej, Eugeniusz Grech, W. Schilf
Abstract: As a result of the Schiff base condensation the gadolinium macroacyclic and macrobicyclic Schiff base complexes have been synthesized and investigated by infrared spectroscopy (IR) and electron paramagnetic resonance (EPR). Both electron ionization and electron spray Molecular Spectroscopy spectra confirmed the [1:1] proportion of a ligand to metal in gadolinium macrocyclic and mocrobicyclic Schiff base complex samples. The thermogravimetrydifferential thermal analysis (TG-DTA) indicated the presence of two water molecules in the innersphere of the macrobicyclic complex and confirmed no water coordination of the metal ion in the macroacyclic complex. The temperature dependence of the integrated intensity of the EPR spectra enabled the magnetic interactions in the spin system of these compounds to be revealed.
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