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René G. Rodriguez - One of the best experts on this subject based on the ideXlab platform.
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Thin Film Growth of Germanium Selenides from PECVD of GeCl_4 and Dimethyl Selenide
Plasma Chemistry and Plasma Processing, 2011Co-Authors: Patrick J. Whitham, Dennis P. Strommen, René G. RodriguezAbstract:Plasma enhanced chemical vapor deposition (PECVD) of germanium Selenide thin films from germanium tetrachloride and Dimethyl Selenide was studied to determine the viability of these reagents for thin film deposition. Germanium tetrachloride and alkylSelenides were selected as candidates for these reactions due to their lower toxicities and higher availabilities compared to the more typical substitutes: germane and hydrogen Selenide in the formation of germanium Selenides. Dimethyl Selenide was used successfully for the deposition of germanium Selenides. Variation in film stoichiometry was observed by the modification of reactant gas flow ratios. Relative mass flow rates were varied in order to determine their effect on germanium chalcogenide deposition, and the effect of these flow rate modifications on the film thickness, structural properties, and composition are reported.
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Erratum to: Thin Film Growth of Germanium Selenides from PECVD of GeCl4 and Dimethyl Selenide
Plasma Chemistry and Plasma Processing, 2011Co-Authors: Patrick J. Whitham, Dennis P. Strommen, Lisa D. Lau, René G. RodriguezAbstract:In the online published article, it was neglected to note that the flow rates listed in the Table 1 for the DMSe flow were based on a nitrogen flow controller. The nitrogen to DMSe flow rate conversion factor was not available for the MKS flow controller that was used. A conversion factor of 0.34 from a different flow controller manufacturer was recently found. The actual DMSe flow rate may be approximated by multiplying the table entry by 0.34. Thus for a flow rate of 5 sccm listed in the table for DMSe, the true flow rate is likely close to (0.34) 9 5 sccm = 1.7 sccm.
John M. Dyke - One of the best experts on this subject based on the ideXlab platform.
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A Study of the Atmospherically Important Reactions between Dimethyl Selenide (DMSe) and Molecular Halogens (X2 = Cl2, Br2, and I2) with ab initio Calculations
The journal of physical chemistry. A, 2012Co-Authors: Lydia Rhyman, Nerina Armata, Ponnadurai Ramasami, John M. DykeAbstract:The atmospherically relevant reactions between Dimethyl Selenide (DMSe) and the molecular halogens (X2 = Cl2, Br2, and I2) have been studied with ab initio calculations at the MP2/aug-cc-pVDZ level of theory. Geometry optimization calculations showed that the reactions proceed from the reagents to the products (CH3SeCH2X + HX) via three minima, a van der Waals adduct (DMSe:X2), a covalently bound intermediate (DMSeX2), and a product-like complex (CH3SeCH2X:HX). The computed potential energy surfaces are used to predict what molecular species are likely to be observed in spectroscopic experiments such as gas-phase photoelectron spectroscopy and infrared matrix isolation spectroscopy. It is concluded that, for the reactions of DMSe with Cl2 and Br2, the covalent intermediate should be seen in spectroscopic experiments, whereas, in the DMSe + I2 reaction, the van der Waals adduct DMSe:I2 should be observed. Comparison is made with previous related calculations and experiments on Dimethyl sulfide (DMS) with m...
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a study of the atmospherically important reactions between Dimethyl Selenide dmse and molecular halogens x2 cl2 br2 and i2 with ab initio calculations
Journal of Physical Chemistry A, 2012Co-Authors: Lydia Rhyman, Nerina Armata, Ponnadurai Ramasami, John M. DykeAbstract:The atmospherically relevant reactions between Dimethyl Selenide (DMSe) and the molecular halogens (X2 = Cl2, Br2, and I2) have been studied with ab initio calculations at the MP2/aug-cc-pVDZ level of theory. Geometry optimization calculations showed that the reactions proceed from the reagents to the products (CH3SeCH2X + HX) via three minima, a van der Waals adduct (DMSe:X2), a covalently bound intermediate (DMSeX2), and a product-like complex (CH3SeCH2X:HX). The computed potential energy surfaces are used to predict what molecular species are likely to be observed in spectroscopic experiments such as gas-phase photoelectron spectroscopy and infrared matrix isolation spectroscopy. It is concluded that, for the reactions of DMSe with Cl2 and Br2, the covalent intermediate should be seen in spectroscopic experiments, whereas, in the DMSe + I2 reaction, the van der Waals adduct DMSe:I2 should be observed. Comparison is made with previous related calculations and experiments on Dimethyl sulfide (DMS) with m...
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A Study of the Atmospherically Important Reactions between Dimethyl Selenide (DMSe) and Molecular Halogens (X2 = Cl2, Br2, and I2) with ab initio Calculations
2012Co-Authors: Lydia Rhyman, Nerina Armata, Ponnadurai Ramasami, John M. DykeAbstract:The atmospherically relevant reactions between Dimethyl Selenide (DMSe) and the molecular halogens (X2 = Cl2, Br2, and I2) have been studied with ab initio calculations at the MP2/aug-cc-pVDZ level of theory. Geometry optimization calculations showed that the reactions proceed from the reagents to the products (CH3SeCH2X + HX) via three minima, a van der Waals adduct (DMSe:X2), a covalently bound intermediate (DMSeX2), and a product-like complex (CH3SeCH2X:HX). The computed potential energy surfaces are used to predict what molecular species are likely to be observed in spectroscopic experiments such as gas-phase photoelectron spectroscopy and infrared matrix isolation spectroscopy. It is concluded that, for the reactions of DMSe with Cl2 and Br2, the covalent intermediate should be seen in spectroscopic experiments, whereas, in the DMSe + I2 reaction, the van der Waals adduct DMSe:I2 should be observed. Comparison is made with previous related calculations and experiments on Dimethyl sulfide (DMS) with molecular halogens. The relevance of the results to atmospheric chemistry is discussed. The DMSeX2 and DMSe:X2 intermediates are likely to be reservoirs of molecular halogens in the atmosphere which will lead on photolysis to ozone depletion
Josef Pola - One of the best experts on this subject based on the ideXlab platform.
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IR laser-induced co-decomposition of Dimethyl Selenide and trisilane: Gas-phase formation of SiSe and chemical vapor deposition of nanostructured H/Si/Se/C polymers
Journal of Photochemistry and Photobiology A-chemistry, 2007Co-Authors: M. Santos, Luis A. Díaz, Markéta Urbanová, Zdeněk Bastl, Jan Šubrt, Josef PolaAbstract:Abstract Chemical changes in IR laser irradiated gaseous mixtures of Dimethyl Selenide and trisilane have been diagnosed by laser-induced fluorescence (LIF) of transient species and by FTIR, Raman, photoelectron spectroscopy and electron microscopy of the final solid products deposited from the gas phase. It is revealed that decomposition of both compounds leads to gas-phase formation of SiSe and deposition of solid nanostructured polymeric materials. We present indirect evidence on the presence of Si Se bonds in these polymers by revealing that these polymers undergo hydrolysis in air to H 2 Se and CH 3 SeH, which converts them to solid silicone-based films containing elemental selenium. Plausible reactions taking place in the gas phase and upon exposure of solids to air are suggested.
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Gas-phase formation of SiSe in IR laser-co-decomposition of Dimethyl Selenide and 1,3-disilacyclobutane
Journal of Organometallic Chemistry, 2007Co-Authors: Luis A. Díaz, M. Santos, Josef PolaAbstract:Abstract A LIF excitation spectrum of SiSe obtained upon IR laser irradiation of gaseous mixture of 1,3-disilacyclobutane and Dimethyl Selenide reveals that the previously reported infrared multiple photon co-decomposition of both compounds involves formation of SiSe. The SiSe formation is explained in terms of reaction of Se atoms with RHSi: silylenes (R = CH3, H) and silene, and elimination of RH from silaneselones (RHSiSe, R = CH3, H).
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IR laser-induced process for chemical vapor deposition of polyselenocarbosilane films
Journal of Analytical and Applied Pyrolysis, 2006Co-Authors: M. Santos, Luis A. Díaz, Markéta Urbanová, Zdeněk Bastl, Jan Šubrt, Dana Pokorná, Josef PolaAbstract:Abstract TEA CO2 laser irradiation into gaseous mixtures of 1,3-disilacyclobutane (DSCB) and Dimethyl Selenide (DMS) results in infrared multiple photon-induced, non-interacting homogeneous decompositions of both educts, one yielding silene (H2Si CH2) and the other elemental selenium as major products. The reaction between polymerizing silene and agglomerizing Se leads to chemical vapor deposition of novel polyselenocarbosilane films which are unstable in atmosphere. The laser induced co-decomposition represents a new process in allowing (i) reaction between thermally generated transient and element and (ii) chemical vapor deposition of the product of this reaction.
Sylvie Nazaret - One of the best experts on this subject based on the ideXlab platform.
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Distribution and genetic diversity of bacterial thiopurine metyltransferases in soils emitting Dimethyl Selenide
Biochimie, 2006Co-Authors: Sabine Favre-bonté, Lionel Ranjard, Ludovic Champier, Benoît Cournoyer, Sylvie NazaretAbstract:Dimethyl Selenide (DMSe) and Dimethyl diSelenide (DMDSe) emissions by soil samples spiked with selenite or (methyl)selenocysteine, with or without a supplement of nutrient broth and glucose were measured. DMSe was the main form of volatile Se produced, and was observed for both Se-substrates. DMDSe was only emitted from soils spiked with (methyl)selenocysteine. Two bacterial thiopurine methyltransferases (TPMTs), TPMT-I and TPMT-E, have been reported to be involved in DMSe and DMDSe emissions [J. Bacteriol. 184 (2002) 3146; Appl. Environ. Microbiol. 69 (2003) 3784]. To establish if these TPMTs or other members of their gene family could have contributed to the DMSe emissions observed, the diversity of bTPMT gene (tpm) sequences among the soils of this study was investigated. Total DNAs from these soils were extracted and screened using the tpm PTCF2–PTCR2 consensus primers defined to PCR amplify this gene family. The PCR products obtained from two soils were cloned, analysed by PCR-RFLP, and sequenced. Their analysis showed an important diversity of tpm lineages (around 12) in soils. Phylogenetic analysis of the deduced TPMT sequences of these soils revealed lineages not previously recorded in the databases, sequences closely related or identical to freshwater TPMTs, or sequences encoding TPMTs closely related to those of Pseudomonas fragi TPMT-K, Pseudomonas Hsa.28 TPMT-I, or Colwellia psychrerythraea TPMT-Z. Nested PCRs, allowing detection of about 13 distinct tpm soil and freshwater lineages by PTCF2–PTCR2 PCR screenings, were performed on the soil total DNAs. These PCRs confirmed the sequencing data, and allowed to recover lineages not detected by the cloning strategy. These results indicate that soils, like the freshwater samples, harbour TPMT-I gene sequences but may also have distinct tpm lineages. This study further supports our hypothesis that TPMTs contribute to DMSe soil emissions.
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characterization of a novel selenium methyltransferase from freshwater bacteria showing strong similarities with the calicheamicin methyltransferase
Biochimica et Biophysica Acta, 2004Co-Authors: Lionel Ranjard, Sylvie Nazaret, Claire Prigentcombaret, Sabine Favrebonte, Claire Monnez, Benoît CournoyerAbstract:Abstract A novel group of Se-methyltransferases is presented. The genetic determinant, named mmtA, which revealed this group was isolated from selenite and selenate-resistant freshwater bacteria. E. coli expressing mmtA and grown with a Se supplement emitted Dimethyl Selenide (DMSe) and Dimethyl diSelenide (DMDSe). Phylogenetic analysis divided MmtA-like bacterial sequences into two clusters, one grouping MmtA with S- and O-methyltransferases, and one grouping UbiE C-methyltransferases. Se methylation by some of these MmtA phyletic neighbours was investigated.
Patrick J. Whitham - One of the best experts on this subject based on the ideXlab platform.
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Thin Film Growth of Germanium Selenides from PECVD of GeCl_4 and Dimethyl Selenide
Plasma Chemistry and Plasma Processing, 2011Co-Authors: Patrick J. Whitham, Dennis P. Strommen, René G. RodriguezAbstract:Plasma enhanced chemical vapor deposition (PECVD) of germanium Selenide thin films from germanium tetrachloride and Dimethyl Selenide was studied to determine the viability of these reagents for thin film deposition. Germanium tetrachloride and alkylSelenides were selected as candidates for these reactions due to their lower toxicities and higher availabilities compared to the more typical substitutes: germane and hydrogen Selenide in the formation of germanium Selenides. Dimethyl Selenide was used successfully for the deposition of germanium Selenides. Variation in film stoichiometry was observed by the modification of reactant gas flow ratios. Relative mass flow rates were varied in order to determine their effect on germanium chalcogenide deposition, and the effect of these flow rate modifications on the film thickness, structural properties, and composition are reported.
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Erratum to: Thin Film Growth of Germanium Selenides from PECVD of GeCl4 and Dimethyl Selenide
Plasma Chemistry and Plasma Processing, 2011Co-Authors: Patrick J. Whitham, Dennis P. Strommen, Lisa D. Lau, René G. RodriguezAbstract:In the online published article, it was neglected to note that the flow rates listed in the Table 1 for the DMSe flow were based on a nitrogen flow controller. The nitrogen to DMSe flow rate conversion factor was not available for the MKS flow controller that was used. A conversion factor of 0.34 from a different flow controller manufacturer was recently found. The actual DMSe flow rate may be approximated by multiplying the table entry by 0.34. Thus for a flow rate of 5 sccm listed in the table for DMSe, the true flow rate is likely close to (0.34) 9 5 sccm = 1.7 sccm.