- Photoionization mass spectrometric studies of the transient species Si2Hn (n = 2-5)
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The transient species Si2H5, Si2H4, Si2H3, and Si2H2 have been prepared for the first time, by reactions of F atoms with Si2H6.The species are generated in situ and studied by photoionization mass spectrometry.The adiabatic ionization potentials are (in e
- Ruscic, B.,Berkowitz, J.
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p. 2416 - 2432
(2007/10/02)
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- Direct kinetic studies of SiH3 + SiH3, H, CCl4, SiD4, Si2H6, and C3H6 by tunable infrared diode laser spectroscopy
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Gas phase reactions of silyl radical, SiH3, are investigated at room temperature using tunable diode laser flash kinetic spectroscopy.Photolytic generation of silyl at 193 and 248 nm is demonstrated using several different precursor systems.The silyl recombination reaction, SiH3 + SiH3 -> Si2H6, is studied by quantitative measurement of SiH3 and attendant product densities.Analysis yields a refinement of the rate constant, krc = (7.9 +/- 2.9) * 10-11 cm3 molecule-1 s-1.By modeling silyl densities following photolysis of HCl in SiH4, bimolecular rate constants for H + SiH3 and H + SiH4 are determined to be (2 +/- 1) * 10-11 and (2.5 +/- 0.5) * 10-13 cm3 molecule-1 s-1, respectively.Reactions of SiH3 with SiD4, Si2H6, CCl4, and C3H6 (propylene) are studied under pseudo-first-order conditions.Derived upper limits to the rate constants show these reactions to be slow at room temperature.The data demonstrate the reactivity of silyl with open-shell (radical) species and the general inertness of silyl toward closed shell molecules.Under typical chemical vapor deposition conditions, SiH3 is, therefore, a kinetically long-lived species in the gas phase and consequently a potentially important film forming species under plasma and photochemical deposition conditions.
- Loh, S. K.,Jasinski, J. M.
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p. 4914 - 4926
(2007/10/02)
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- Gas-phase homolytic substitution reactions of hydrogen atoms at silicon centers
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The reaction of H atoms with a number of mono-, di-, and trisilanes has been studied with the view of examining the possible occurrence of a homolytic substitution reaction (SH2). Arrhenius parameters for abstraction plus substitution have been determined for the reaction of H atoms with Si2H6, Me3SiSiMe2H, Me3SiSiCl3, Si2Cl6, and Me8Si3. The ratio of substitution vs. abstraction was determined. It is found that di- and trisilanes react fast by an SH2 reaction while monosilanes are unreactive. Ligands with a -I effect cause a decrease in reactivity. The experimental facts are explained by a frontside attack of the H atoms due to the favorable interaction of the singly occupied orbital at the H atom with the energetically high-lying Si-Si orbital.
- Fabry,Potzinger,Reimann,Ritter,Steenbergen
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p. 1231 - 1235
(2008/10/08)
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