Infrared spectra of carbonyl fluorides and general harmonic force field

Relative Rate and Product Studies of the Reactions of Atomic Chlorine with Tetrafluoroethylene, 1,2-Dichloro-1,2-difluoroethylene, 1,1-Dichloro-2,2-difluoroethylene, and Hexafluoro-1,3-butadiene in the Presence of Oxygen

Rate coefficients k1-k3 have been measured for Cl atom reactions with CF2═CF2, CFCl═CFCl, and CCl2═CF2 relative to k4 for CF2═CF-CF═CF2 at 293 ± 2 K. k4 was remeasured relative to Cl + ethane. Cl was generated by UV photolysis of Cl2, and other species were monitored by FT-IR spectroscopy. The measurements yield k1 = (6.6 ± 1.0) × 10(-11), k2 = (6.5 ± 1.0) × 10(-11), and k3 = (7.1 ± 1.1) × 10(-11) cm(3) molecule(-1) s(-1), respectively, and k4 = (8.0 ± 1.2) × 10(-11) cm(3) molecule(-1) s(-1) is proposed. These results are discussed in the context of atmospheric chemistry. Subsequent chemistry in the presence of oxygen leads to oxygenated products that are identified via their IR spectra, and possible mechanisms are discussed. The yield of CF2O from C2F4 is 93 ± 7%. Dichlorofluoroacetyl fluoride (CCl2FCFO) was observed as a product from CFClCFCl, and chlorodifluoroacetyl chloride (CClF2CClO) was observed from CCl2CF2 oxidation. C4F6 led to 66 ± 5% CF2O and 38 ± 3% OCF2CFC(F)═O. Reaction enthalpies and enthalpy barriers computed via CBS-QB3 theory help rule out some unfavorable mechanistic steps.

Mercury-fluorine interactions: a matrix isolation investigation of Hg...F2, HgF2 and HgF4 in argon matrices

HgF(2) and Hg have been trapped in dilute F(2)/Ar and neat F(2) matrices, subjected to UV-Vis and vac-UV photolysis and annealing, with the products identified by FTIR, UV-Vis-NIR and Hg L(3)-edge XAFS spectroscopic techniques. Whilst there was no convincing evidence for the formation of HgF(4) under our argon matrix isolation conditions, a new Hg...F(2) complex was identified and subsequent photolysis yielded HgF(2) very cleanly. Hg L(3)-edge EXAFS has provided the first experimental value of 1.94(2) A for the Hg-F bond length in HgF(2), which is in excellent agreement with the computational values incorporating relativistic effects.

Thermolysis of Fluorinated Single-Walled Carbon Nanotubes: Identification of Gaseous Decomposition Products by Matrix Isolation Infrared Spectroscopy

The thermal decomposition of fluorinated single-walled carbon nanotubes (F-SWNTs), known to result in pristine SWNTs, has been investigated by freezing the gaseous products formed at temperatures between 50 and 500 degrees C under high vacuum in an argon matrix at 10-20 K and analyzing the trapped species by IR spectroscopy. The major products of F-SWNT decomposition are carbonyl fluoride (COF2) below 300 degrees C and CF4 above 300 degrees C. For comparison, graphite fluoride is stable thermally up to 300 degrees C under these conditions, and the major gas-phase species at temperatures below 500 degrees C are CF4 and the CF3 radical. F-SWNTs are thermally less stable than graphite fluoride, and etching of the nanotubes is observed at lower thermolysis temperatures.

Photoisomerization of Matrix-Isolated Bis(trifluoromethyl) Sulfoxide: Formation of the Sulfenic Ester CF3SOCF3

Bis(trifluoromethyl) sulfoxide, CF(3)S(O)CF(3), isolated in noble gas matrixes at low temperatures, isomerizes upon UV irradiation into the sulfenic ester CF(3)SOCF(3). The new species is characterized spectroscopically, and the vibrational assignment is supported by (18)O isotopic labeling experiments and by DFT calculations. The calculated structural parameters of CF(3)SOCF(3) are compared with the calculated and experimental data of the related compounds CF(3)SSCF(3) and CF(3)OOCF(3). In addition, the computed enthalpy differences between the sulfoxide R(2)S=O and sulfenate RSOR structures for R = H, F, CH(3), and CF(3) are included.

The High-Resolution Infrared Spectrum of the nu1/2nu2 Fermi Dyad Bands of COF2

High-resolution FTIR data of carbonyl fluoride in the region of the C-O stretch nu1 fundamental have been analyzed. Satisfactory interpretation of the spectral data required a rigorous analysis that involved the inclusion of Fermi resonance with the 2nu2 state and Coriolis interaction with the 2nu3 + nu6 dark state. Deperturbed molecular constants for the three interacting states as well as perturbation parameters that fit the data within the limits of the experimental accuracy of approximately 0.00035 cm-1 have been obtained. Interesting evidence of "axis interchange" in the 2nu2 state has been observed. Copyright 1997 Academic Press. Copyright 1997Academic Press

ATMOS data processing and science analysis methods

The ATMOS (atmospheric trace molecule spectroscopy) instrument, a high speed Fourier transform spectrometer operating in the middle IR (2.2-16 microm), recorded more than 1500 solar spectra at approximately 0.0105-cm(-1) resolution during its first mission onboard the shuttle Challenger in the spring of 1985. These spectra were acquired during high sun conditions for studies of the solar atmosphere and during low sun conditions for studies of the earth's upper atmosphere. This paper describes the steps by which the telemetry data were converted into spectra suitable for analysis, the analysis software and methods developed for the atmospheric and solar studies, and the ATMOS data analysis facility.