13537-33-2Relevant articles and documents
Doppler-limited dye laser excitation spectroscopy of the >A (000)->A'(000) band of HSiF
Suzuki, Tetsuo,Hakuta, Kohzo,Saito, Shuji,Hirota, Eizi
, p. 3580 - 3583 (1985)
The >A (000)->A'(000) band of HSiF was observed by Doppler-limited dye laser excitation spectroscopy.The HSiF molecule was produced by the reaction of SiH3F with microwave discharge products of CF4.The observed spectrum was found to be almost free of perturbations and was readily assigned to about 1300 transitions of Ka' - Ka = 5-6, 4-5, 3-4, 2-3, 1-2, 0-1,1-0, 2-1, 3-2, 4-3, 5-4, 0-0,1-1, and 2-0.A least-squares analysis of the observed spectrum yielded the rotational constants and the centrifugal distortion constants for both the and states.The molecular structure was discussed using the observed rotational constants.
Single vibronic level emission spectroscopy of jet-cooled HSiF and DSiF
Hostutler, David A.,Clouthier, Dennis J.,Judge
, p. 10728 - 10732 (2007/10/03)
The ground state harmonic frequencies of jet cooled HSiF and DSiF were obtained using single vibronic level emission spectroscopy. An equilibrium structure was obtained from the centrifugal distortion constants of the non-constrained harmonic force field.
Rotational state-specific dynamics of SiF C2Δ-B2Σ+ collision-induced transfer
Jackson, Neil A.,Randall, Colin J.,McKendrick, Kenneth G.
, p. 51 - 59 (2007/10/03)
Laser excitation on the C2Δ-X2Π transition was used to prepare discrete rotational levels of the SiF C2Δ, υ = 0 state, allowing their state-specific collisional behavior to be investigated. Time- and wavelength-resolved returning C-X fluorescence spectra established that the initial populations were only partially perturbed by rotationally inelastic processes within the C2Δ state at the typical pressures of our experiments. Transfer within the F1 manifold appears to be favored by a factor of ～2 over transfer from F1 to F2. There is relatively little dependence on rotational state (in the range j = 2.5-21.5) of the rate constant for total collisional removal of the C2Δ state by either H2 or N2. As previously established, a fraction of the collisionally removed population is deposited in the lower-lying B2Σ+ state. Dispersed B-X fluorescence spectra revealed broad rotational distributions in the predominant B2Σ+, υ′ = 0 product level in collisions with H2 and N2, indicating substantial release of rotational energy during the transfer between electronic states. There is a positive correlation between the peak and average product j′ and the initial rotational state j. The main features of the observed behavior are reproduced by a limiting impulsive model. We believe this to be a consequence of the respective valence and Rydberg characters of the C2Δ and B2Σ+ states.
Pulsed discharge jet spectroscopy of DSiF and the equilibrium molecular structure of monofluorosilylene
Harper, Warren W.,Hostutler, David A.,Clouthier, Dennis J.
, p. 4367 - 4375 (2007/10/03)
The jet-cooled laser induced fluorescence excitation spectrum of the ? 1A″- X? 1A′ band system of DSiF has been observed using the pulsed discharge jet technique. Vibrational analysis of the spectrum yielded upper state harmonic vibrational frequencies of ω1 = 1322, ω2 = 444, and ω3 = 867 cm-1. Vibronic bands involving all of the upper state fundamentals of HSiF and DSiF have now been rotationally analyzed, allowing a determination of the excited state equilibrium structure as r′e(SiH) = 1.526 ± 0.014 ?, r′e(SiF) = 1.597 ± 0.003 ?, and θ′e(HSiF) = 115.0 ± 0.6°. The harmonic frequencies and centrifugal distortion constants were used to obtain harmonic force fields and average (rz) structures for the ground and excited states. The ground state average structure was used to estimate the equilibrium structure of r″e(SiH) = 1.528 ± 0.005 ?, r″e(SiF) = 1.603 ± 0.003 ?, and θ″e(HSiF) = 96.9 ± 0.5°.
Large rotational energy release in collision-induced SIF C(2)Δ-B(2)Σ(+) valence-Rydberg transfer
Jackson, Neil A.,Watson, Cameron W.,McKendrick, Kenneth G.
, p. 564 - 570 (2008/10/08)
Distinct rotational population distributions were prepared in SiF C(2)Δ, v=0 radicals by laser excitation. Collisions with H2 or N2 transferred a fraction of the C(2)Δ molecules to the lower-lying B(2)Σ(+) state. B-X fluorescence spectra revealed the nasc
Matrix Reactions of SiH4 and GeH4 with F2. Infrared Spectra of Several HF Product Complexes
McInnis, Thomas C.,Andrews, Lester
, p. 5276 - 5284 (2007/10/02)
Silane and germane were condensed with F2 at high dilution in argon on a 13 +/- 1 K substrate.Weak product complexes produced on condensation and increased by ultraviolet photolysis are assigned to SiH3F..HF, SiH2..HF or SiH2..(HF)2, and HSiF..HF.Annealing produced new bands due to F atom reactions that are attributed to SiH3..HF.The GeH3F molecule was observed in the similar GeH3F..HF complex.H-F vibrations in these complexes suggest that F is more basic in GeH3F than in SiH3F owing to the more electropositive nature of germanium as compared to silicon.
Unimolecular Decomposition of SiH4, SiH3F, and SiH2F2 at High Temperatures
Koshi, Mitsuo,Kato, Shin,Matsui, Hiroyuki
, p. 1223 - 1227 (2007/10/02)
The thermal decomposition of SiH4, SiH3F, and SiH2F2 diluted in Ar was studied behind incident shock waves by monitoring IR emission from these reactant molecules.The rate constants of the unimolecular decomposition for all of three molecules were found t
LASER-INDUCED FLUORESCENCE SPECTROSCOPY OF SiF PRODUCED BY IR MULTIPLE-PHOTON DISSOCIATION OF SiF4
Popov, V. K.,Rossberg, M.,Strube, W.,Wollbrandt, J.,Linke, E.
, p. 225 - 230 (2007/10/02)
Excitation spectra and dispersed fluorescence were measured in the β-system (B2Σ-X2?) of the SiF radical produced by multiphoton dissociation (MPD) of SiF4 with a TEA CO2 laser.Within the limits of error no effect of the wavelength of the photolysis laser on the spectra was found.Formation and decay kinetics of SiF during and after IR laser excitation, as monitored by LIF, are also presented.The temporal behaviour if the SiF LIF signal was different for different wavelengths of the CO2 laser.For wavelengths close to the linear absorption band there was no induction period in the formation of SiF.The pressure dependence of the kinetics was different for the two CO2 laser branches.
THERMAL REACTIONS OF F2 AND NF3 WITH SILICON(110) STUDIED BY LASER IONIZATION MASS SPECTROMETRY
Squire, D. W.,Dagata, J. A.,Hsu, D. S. Y.,Dulcey, C. S.,Lin, M. C.
, p. 2827 - 2834 (2007/10/02)
The techniques of laser and electron ionization mass spectrometry have been employed to study the thermal etching of Si(110) by F2 and NF3 at substrate temperatures between 300 and 1200 K.By two-photon resonance-enhenced ionization of SiF2 via the B1B2 state, the apparent activation energy for gaseous silicon difluoride production was found to be 8.9+/-0.3 and 22.1+/-1.7 kcal/mol for F2 and NF3, respectively.SiF was not detected.An extensive search for SiF3 during etching by F2 at 1000 K, by means of resonance ionization from 320 to 325 and from 416 to 510 nm, also showed no signs of the species.Both SiF and SiF3 are thermochemically unimportant etch products under the conditions employed.In F2 etching, SiF4 and total silicon fluoride ΣSiFx+ signals as measured by electron ionization rose rapidly at lower temperatures and stabilized between 700 and 900 K before rising again.No such behavior was observed for SiF2 production from F2 or for the products formed in NF3 etching.Apparent activation energies for total silicon fluoride and SiF4 production are similar.For F2, they were found to be abaut 9 kcal/mol in the low-temperature region, and for NF3 both were measured to be abaut 21 kcal/mol.A proposed reaction mechanism explaining these and related results is discussed.
Energetics and dynamics in the reaction of Si+ with SiF4. Thermochemistry of SiFx and SiF+x (x=1, 2, 3)
Weber, M. E.,Armentrout, P. B.
, p. 6898 - 6910 (2007/10/02)
The title reaction is studied using guided ion beam mass spectrometry.Absolute reaction cross sections are measured as a function of kinetic energy from thermal to 40 eV, and three endothermic product channels are observed.The dominant SiF+ + SiF3 channel is only slightly endothermic, while the SiF3+ + SiF and SiF2+ + SiF2+ channels have much higher thresholds.The SiF3+ cross section magnitude is about half that of SiF+, while the SiF2+ cross section is an order of magnitude smaller than that of SiF+.A second feature which appears in the SiF2+ cross section is due to dissociation of SiF3+ .There is evidence that SiF+ and SiF3+ are produced via a direct mechanism.Competition between these two channels is interpreted in terms of molecular orbital correlations and qualitative potential energy surfaces.One surface is found to correlate only with the SiF3+ + SiF channel, while another correlates diabatically with this channel and adiabatically with the SiF+ + SiF3 channel.Competition on this latter surface has an energy dependence which is consistent with the Landau-Zener model.Reaction thresholds are analyzed to yield 298 K heats of formation for SiFx and SiFx+ species.From an evaluation of these and literature values, we recommend the following values:.
