Infrared Detection of Gaseous Trifluoromethyl Radical

Carlson, G.A.; Pimentel, George C.

doi:10.1063/1.1726574

Cited by 67 publications

(8 citation statements)

References 6 publications

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“…Previously, in the photodissociation of CF 3 I, only the 701 cm –1 vibrational states of the CF 3 radical had been resolved in the PTS, and the 701 cm –1 vibrational mode was generally assigned to the ν 2 umbrella vibration. − While in the close-coupling calculation, Clary showed that both 701 and 1086 cm –1 modes , contain two vibration characters, but the 701 cm –1 mode has more CF symmetric stretch character and the 1086 cm –1 mode has more umbrella character. He also suggested the preferential (v 1 , v 2 ) combination states for the CF 3 fragment.…”

Section: Introductionmentioning

confidence: 99%

Resolved (v₁, v₂ = 1) Combination Vibrational States of CF₃ Fragments in the Photofragment Translational Spectra of CF₃I

Lin

Liu

et al. 2016

J. Phys. Chem. A

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The photodissociation of CFI → CF(v,v) + I*/I has been investigated at 248, 266, and 277 nm with our high resolution mini-TOF photofragment translational spectrometer. Based on the theoretical calculations of Clary and of Bowman et al., now in this manuscript, we assign 701 cm to the CF symmetric stretch (breathing) ν mode, and 1086 cm to the umbrella ν mode of the CF fragment. In the obtained TOF spectra of I from the I* channel, situated in the 701 cm gaps between the original series of (v, 0) vibrational peaks, a new series of weaker (v, 1) vibrational peaks are partially resolved. These observed new peaks with 1086 cm ν mode excitation have never been reported in previous literature. In the TOF spectra of I from the I channel, the new series of (v, 1) peaks are also partially resolved. However, these spectra of I channel are less satisfactory, because for higher E and higher E, the higher resolution of PTS is required. The potential energy at the curve crossing point and the excitation of CF (v, 2) and (v, 3) vibrational states have been also analyzed.

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Section: Introductionmentioning

confidence: 99%

Resolved (v₁, v₂ = 1) Combination Vibrational States of CF₃ Fragments in the Photofragment Translational Spectra of CF₃I

Lin

Liu

et al. 2016

J. Phys. Chem. A

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“…Most notably, in the case of the fluorine-substituted analogues (CH n F 3-n ), deviations from planarity with increasing fluorine substitution have been revealed: CH 3 is well-known to be planar, 12 CH 2 F is quasiplanar, 4 while CHF 2 and CF 3 exhibit an increasing pyramidal structure. [1][2][3][13][14][15] In contrast, both CH 2 Cl and CH 2 Br radicals are clearly planar with significant electron delocalization on the corresponding halogen, [16][17][18] while the degree of electron delocalization in CH 2 F is less pronounced. 4 These differences have been interpreted in terms of the much larger difference in the electronegativities of carbon and fluorine.…”

Section: Introductionmentioning

confidence: 99%

“…A very interesting example of such seeming similarities is given by the methyl radical and its halogen-substituted derivatives, denoted CH n X 3− n where n = 0−2 and X = F, Cl, Br, and I. Indeed, early studies by electron spin resonance, infrared , and microwave spectroscopy, as well as photoionization measurements and ab initio calculations have provided numerous evidence that the interaction of the lone pairs of the halogen atom(s) with the unpaired electron affects the bonding considerably: the carbon−halogen stretching force constants exceed normal C−X values − (such as in CH 3 X molecules), and large anharmonicity in the out-of-plane vibration modes − has been observed. Most notably, in the case of the fluorine-substituted analogues (CH n F 3− n ), deviations from planarity with increasing fluorine substitution have been revealed: CH 3 is well-known to be planar, CH 2 F is quasiplanar, while CHF 2 and CF 3 exhibit an increasing pyramidal structure. − ,− In contrast, both CH 2 Cl and CH 2 Br radicals are clearly planar with significant electron delocalization on the corresponding halogen, − while the degree of electron delocalization in CH 2 F is less pronounced .…”

Section: Introductionmentioning

confidence: 99%

Hyperfine Resolved Fourier Transform Microwave and Millimeter-Wave Spectroscopy of the Iodomethyl Radical, CH₂I (X̃²B₁)

Bailleux¹,

Kania²,

Skřínský³

et al. 2010

J. Phys. Chem. A

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Fourier-transform microwave and millimeter-wave spectra of the iodomethyl radical, CH(2)I, have been observed in the ground vibronic state in the frequency ranges 17-38 GHz and 200-610 GHz, respectively. The pi-electron radical was produced either by iodine abstraction from diiodomethane (CH(2)I(2)) or by hydrogen abstraction from iodomethane (CH(3)I). Seventy-three hyperfine resolved lines owing to the two hydrogen and to the iodine nuclei have been detected in the microwave region, including K(a) = 0 (ortho species) and K(a) = 1 (para species). No hyperfine splitting due to the hydrogen nuclei could be observed for the para species, directly confirming the planarity of the radical and that the ground electronic state is (2)B(1). More than 400 a-type transitions that span the values N' < or = 35, K(a) < or = 6, were detected. A global least-squares analysis of the measured lines was conducted and led to the determination of an exhaustive list of molecular constants. In particular, the sign of the Fermi-contact constant of iodine was unambiguously determined to be negative, which is opposite to that of the other monosubstituted halomethyl radicals. This work allowed a systematic comparison of the structural and bonding properties among the CH(2)X analogues (where X = F, Cl, Br, and I) owing to the hyperfine coupling constants of both the hydrogen and halogen nuclei.

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“…Matrixisolation studies of CF 3 by Jacox and co-workers 15 determined the vibrational frequencies in C 3V symmetry. Gas-phase vibrational frequencies were assigned by Carlson et al 16 in a flash photolysis experiment and by Bozlee et al 17 by coherent anti-Stokes Raman spectroscopy (CARS). Infrared diode laser spectroscopy was also applied for an accurate determination of the geometry.…”

Section: Introductionmentioning

confidence: 99%

Photodetachment Imaging Studies of the Electron Affinity of CF₃

2000

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The photoelectron spectra of the trifluoromethyl anion, CF3 -, at 355 and 258 nm are reported. Simulation of the partially resolved vibrational structure is used to extract the adiabatic electron affinity, AEA[CF3] = 1.82 ± 0.05 eV. The heat of formation for the trifluoromethyl anion derived from the adiabatic electron affinity (Δ [CF3 -] = −153.4 ± 1.5 kcal/mol) is compared to the high-accuracy “isodesmic bond additivity corrected” (BAC) complete basis set (CBS-Q) theory prediction (Δ [CF3 -] = −152.6 kcal/mol). We find the CBS-Q prediction of Δ [CF3] = −112.1 kcal/mol, after BAC, to be in excellent agreement with the most recent experimental determination of the radical heat of formation. The photoelectron angular distribution at 355 nm was also extracted from the photoelectron image, revealing p wave photodetachment with an energy-averaged anisotropy parameter of β = 1.5 ± 0.1.

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Infrared Detection of Gaseous Trifluoromethyl Radical

Cited by 67 publications

References 6 publications

Resolved (v₁, v₂ = 1) Combination Vibrational States of CF₃ Fragments in the Photofragment Translational Spectra of CF₃I

Resolved (v₁, v₂ = 1) Combination Vibrational States of CF₃ Fragments in the Photofragment Translational Spectra of CF₃I

Hyperfine Resolved Fourier Transform Microwave and Millimeter-Wave Spectroscopy of the Iodomethyl Radical, CH₂I (X̃²B₁)

Photodetachment Imaging Studies of the Electron Affinity of CF₃

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Infrared Detection of Gaseous Trifluoromethyl Radical

Cited by 67 publications

References 6 publications

Resolved (v1, v2 = 1) Combination Vibrational States of CF3 Fragments in the Photofragment Translational Spectra of CF3I

Resolved (v1, v2 = 1) Combination Vibrational States of CF3 Fragments in the Photofragment Translational Spectra of CF3I

Hyperfine Resolved Fourier Transform Microwave and Millimeter-Wave Spectroscopy of the Iodomethyl Radical, CH2I (X̃2B1)

Photodetachment Imaging Studies of the Electron Affinity of CF3

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Resolved (v₁, v₂ = 1) Combination Vibrational States of CF₃ Fragments in the Photofragment Translational Spectra of CF₃I

Resolved (v₁, v₂ = 1) Combination Vibrational States of CF₃ Fragments in the Photofragment Translational Spectra of CF₃I

Hyperfine Resolved Fourier Transform Microwave and Millimeter-Wave Spectroscopy of the Iodomethyl Radical, CH₂I (X̃²B₁)

Photodetachment Imaging Studies of the Electron Affinity of CF₃