K.C. Kim

Analysis of the ν4 (615 cm−1) region of the Fourier transform and diode laser spectra of SF6☆

A detailed analysis of the nu/sub 4/ fundamental band in SF/sub 6/ is presented. Both from the intermediate resolution (0.04 cm/sup -1/) FT-IR and high resolution (approx. 1 x 10/sup -4/ cm/sup -1/) diode laser measurements the frequencies of the rotational transitions as well as the fine splitting parameters of the individual rotational manifolds have been determined. Well-resolved rotational sublevels of several extremely high angular momentum states (J > 100) have been recorded using a kilometer optical path diode laser spectrometer, and the observed pattern of Coriolis substructures is shown to be in good agreement with the theory.

A study of the absolute infrared intensity of ν3, absorption from vibrationally excited molecules, and the vapor pressure of UF6

Results are presented from laser diode studies of ν3 transition of UF6 in the 16 μm region using a very long optical path absorption cell. The ν3 Q‐branch and several individual rotational transitions have been recorded in the temperature range between 165 and 295 K. From the ν3 band contour analysis and the line intensity measurements, the vibrational band strength of the ν3 transition, S0V=710±120 km mole−1, was obtained. From absorption measurements of a UF6 sample in the cooled cell at pressures from 10−3 to 10−5 Torr, the vapor pressure curve of UF6 was extended to the temperature range down to 165 K. A new technique is described allowing us to obtain diode laser ’’survey’’ spectra over a range of 25 cm−1 by ’’mode scans.’’ This technique allows us to measure the changes in the band shape of ν3 as a function of temperature, and thus learn something about ’’hot band’’ absorption from vibrationally excited molecules.

The infrared spectrum and vibrational intensity of gaseous dioxygen difluoride (FOOF)

Abstract A complete absorption spectrum of gaseous dioxygen difluoride (FOOF) was obtained using a very long pathlength, temperature-programmable cell and an FT-IR spectrometer. All six fundamental vibrational frequencies were deduced from three fundamental bands and four binary combination bands. A significant deviation of the v frequency is observed from the matrix studies of solid FOOF. The absolute vibrational intensities of observed bands are reported.

The 3v3 overtone band in UF6

Abstract We report the observation of the spectrum of the 3 v 3 Q branch in UF 6 at both low (1.4 cm −1 ) and high (0.004 cm −1 > resolution. The most prominent feature of the spectrum is the five-sub-bandheads between 1875.4 and 1875.6 cm −1 . The transition strength for 3 v 3 is Γ 0,3 = 3.8 × 10 −2 km mole −1 .

Laser flash photolysis of O2 and F2 mixtures: The O2F ν1 band at 6.7 μm

Abstract We report the first experimental observation of the ν 1 band (OO stretching) of the O 2 F radical in the gas phase and its equilibrium existence with O 2 F 2 . The radical was formed by laser flash photolysis of O 2 and F 2 mixtures in a very long pathlength cell and the detection was done by a Fourier transform infrared spectrometer.

The infrared absorption spectrum of the isolated UF5 molecule in the 580–630 cm−1 region

Abstract The infrared absorption spectrum in the 16–17 μm region of the transient UF 5 molecule formed from laser photolysis of UF 6 is presented. The absorption contour and the intesity measurements allow tentative assignment of the molecular structure.

The absorption spectrum of laser-produced UF5 molecules in the 350–700 nm region

Abstract UF 5 molecules are generated from the laser photolysis of UF 6 samples in an absorption cell and the low-resolution absorption features in the 350–700 nm region of the UF 6 photodissociation products have been characterized.

Vibrational anharmonicity constants for UF6: The ν3 transitions at 16 μm

Assignment of nine hot‐band Q branches in the ν3 (16 μm) region of the diode laser spectrum of UF6, and measurement of their wave number displacements from the origin of the fundamental band, provide values of effective anharmonicity constants x34, x35, and x36. The relationship x3j = −aω0j, where a = (1.28±0.08)×10−3 and ω0j = normal‐mode wave number for j = 4, 5, or 6, has been used to compute spectra in good qualitative agreement with observed spectra between T = 170 K and room temperature.

Diode laser spectroscopy of the transient VF5 radical following laser photolysis of VF6

Abstract Laser photolysis of low pressure samples of gaseous UF 6 in a long path cell produces transient UF 5 radicals. Absorption by these radicals in the 16 μm - 17μμm region of the infrared spectrum has been observed with an infrared diode laser monitor. The observed lifetime of the absorbing species is long (~500 μs) and suggests an additional channel for the production of uf 5 at low pressures. Absorption by excited UF 6 molecules formed by recombination of F atoms and VF 5 radicals has also been recorded.

Laser flash photolysis of UF6: The 17 μm infrared spectrum of the transient UF5 molecule

Abstract UF 5 molecules were produced from laser photolysis of very low pressure samples of UF 6 in a long path cell. The partial infrared absorption spectrum of the initially formed UF 5 molecule was recorded in the 17 μm region. The extent of internal vibrational excitation of the formed molecule and its lifetime are discussed from analysis of the absorption decay curve and the measured spectral contour.