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Si–H bending modes as a probe of local chemical structure: Thermal and chemical routes to decomposition of H2O on Si(100)-(2×1) (2000)

Weldon, M. K. ; Queeney, K. T. ; Gurevich, A. B. ; [et al.]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 113 (2000), S. 2440-2446

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ISSN: 1089-7690

Source: AIP Digital Archive

Topics: Physics , Chemistry and Pharmacology

Notes: Surface infrared spectroscopy and density functional cluster calculations are used to study the thermal and atomic hydrogen-induced decomposition of water molecules on the clean Si(100)-(2×1) surface. We report the first observation of the Si–H bending modes associated with the initial insertion of oxygen into the dimer and backbonds of a silicon dimer. We find that, while one and two oxygen-containing dimers are formed almost simultaneously during the thermal decomposition of water on this surface, atomic H can be used to drive the preferential formation of the singly oxidized dimer. This work highlights the sensitivity of Si–H bending modes to the details of local chemical structure in an inhomogeneous system, suggesting that the combined experimental and theoretical approach demonstrated herein may be extremely useful in studying even more complex systems such as the hydrogenation of defects in SiO2 films. © 2000 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.482061

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Thermophysical Properties of Tetramethylmethane and Tetramethylsilane Gas Calculated by Means of an Isotropic Temperature-Dependent Potential (2000)

Zarkova, L. ; Pirgov, P. ; Hohm, U. ; [et al.]

Springer

International journal of thermophysics 21 (2000), S. 1439-1461

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ISSN: 1572-9567

Keywords: diffusion ; intermolecular potentials ; Raman and Rayleigh spectra ; second virial coefficients ; tetramethylmethane ; tetramethylsilane ; transport properties ; viscosity

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract An isotropic temperature-dependent potential (ITDP) is calculated for the description of binary interactions in gaseous tetramethylmethane, C(CH3)4, and tetramethylsilane, Si(CH3)4. The potential parameters of C(CH3)4 and Si(CH3)4 are determined by solving an inverse problem of minimization of the sum of weighted squared relative deviations between experimental and calculated pure gas viscosity (η), second (pVT)-virial coefficient (B), and second acoustic virial coefficient (β) data. At T=0 K they are obtained for C(CH3)4 and Si(CH3)4, respectively, as repulsive parameter n=28.02(12) and 20.79(11), equilibrium distance r m=5.7790(30)×10−10 and 5.9051(36)×10−10 m, potential well depth ε/k B=586.32(42) and 674.75(91) K, and the first excited-level enlargement δ=0.0141(3)×10−10 and 0.0188(3)×10−10 m. The influence of the temperature on the potential parameters r m(T) and ε(T) is implied in the temperature dependence of the effective excited-state enlargement, calculated via the vibrational partition function. The calculated complete sets of normal vibrational frequencies for C(CH3)4 and Si(CH3)4 are consistent with the available experimental data. In addition, good agreement is observed between the calculations and new Raman spectroscopic measurements on C(CH3)4. Tables for recommended thermophysical properties (B, η, and self-diffusion ρD) and effective potential parameters (r m and ε) of the two globular gases are given for the temperature range between 250 and 800 K.