Spectroscopic Identification of the Resonance-Stabilized cis- and trans-1-Vinylpropargyl Radicals

Reilly, Neil J.; Nakajima, Masakazu; Troy, Tyler P.; Chalyavi, Nahid; Duncan, K; Nauta, Klaas; Kable, Scott H.; Schmidt, Timothy W.

doi:10.1021/ja904521c

Cited by 45 publications

(60 citation statements)

References 46 publications

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“…Comparison of the observed frequencies with those calculated for I2MR and 2MIR (see ESI †) reveals that only I2MR can account for all of the observed frequencies. As has been shown to be effective in the past, 12,13 ground-state frequencies were scaled by 0.97. We find that the scaled calculated I2MR frequencies show good agreement with experiment, allowing for facile assignment of the origin dispersed fluorescence spectrum.…”

Section: 1328mentioning

confidence: 99%

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The spectroscopy and thermochemistry of phenylallyl radical chromophores

et al. 2011

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The resonant two-color two-photon ionization and laser induced fluorescence excitation spectra of the 1-phenylallyl (cinnamyl) and inden-2-ylmethyl radicals are reported. The 1-phenylallyl radical is found to fluoresce with low yield, permitting only a coarse dispersed fluorescence spectrum, while the inden-2-ylmethyl radical yields sufficient fluorescence to obtain ground-state vibrational frequencies and twodimensional fluorescence spectra. Computed ionization energies and thermochemical properties including radical stabilization energies are reported for a range of resonance-stabilized radicals, including the phenylpropargyl, vinylpropargyl and phenylallyl radicals.

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Section: 1328mentioning

confidence: 99%

“…11,12 This radical was found to be the most conspicuous fluorescent species in this environment after the ever-present C 2 , C 3 and CH molecules. In addition, another product of this and other hydrocarbon discharges was identified as the cis-and trans-1-vinylpropargyl radicals 13 ( Fig. 1, 1VPR).…”

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confidence: 91%

The spectroscopy and thermochemistry of phenylallyl radical chromophores

et al. 2011

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“…Our investigation is based on the technique of two-dimensional laser induced fluorescence (2D-LIF). [16][17][18][19][20][21][22][23][24][25] This technique involves measuring a region of the dispersed fluorescence spectrum as the laser is scanned over absorption features. The dispersed fluorescence effectively provides a filter that allows different species to be separated.…”

Section: Introductionmentioning

confidence: 99%

Methyl rotor dependent vibrational interactions in toluene

Gascooke

Lawrance

2013

The Journal of Chemical Physics

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The methyl rotor dependence of a three state Fermi resonance in S 1 toluene at ∼460 cm −1 has been investigated using two-dimensional laser induced fluorescence. An earlier time-resolved study has shown the Fermi resonance levels to have different energy spacings at the two lowest methyl rotor states, m = 0 and 1 [J. A. Davies, A. M. Green, and K. L. Reid, Phys. Chem. Chem. Phys. 12, 9872 (2010)]. The overlapped m = 0 and 1 spectral features have been separated to provide direct spectral evidence for the m dependence of the resonance. The resonance has been probed at m = 3a 1 for the first time and found to be absent, providing further evidence for a large change in the interaction with m. Deperturbing the resonance at m = 0 and 1 reveals that the m dependence arises through differences in the separations of the "zero-order," locally coupled states. It is shown that this is the result of the local "zero-order" states being perturbed by long-range torsion-vibration coupling that shifts their energy by small amounts. The m dependence of the shifts arises from the m = ±3n (n = 1, 2, . . . ) coupling selection rule associated with torsion-rotation coupling in combination with the m 2 scaling of the rotor energies, which changes the E for the interaction for each m. There is also an increase in the number of states that can couple to m = 1 compared with m = 0. Consideration of the magnitude of reported torsion-rotation coupling constants suggests that this effect is likely to be pervasive in molecules with methyl rotors.

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“…Of the known gas-phase spectra of neutral, closed-shell PAHs, including up to C 42 H 18 , there is no match with a DIB (Salama et al 2011). Fewer neutral radicals have been studied, but there is an emerging body of work on resonance-stabilized radicals (RSRs) containing up to 13 carbon atoms which suggests that these species are also not DIB carriers (Reilly et al 2008(Reilly et al , 2009Troy et al 2009;Sebree et al 2010;Troy et al 2011;Chalyavi et al 2010;Sebree et al 2011;O'Connor et al 2011). …”

Section: Introductionmentioning

confidence: 99%

On the electronic spectroscopy of closed-shell cations derived from resonance-stabilized radicals: Insights from theory and Franck-Condon analysis

Troy

Kable

Schmidt

et al. 2012

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Context. Recent attention has been directed on closed-shell aromatic cations as potential carriers of the diffuse interstellar bands. The spectra of mass-selected, matrix-isolated benzylium, and tropylium cations were recently reported. The visible spectrum of benzylium exhibits a large Franck-Condon (FC) envelope, inconsistent with diffuse interstellar band carriers. Aims. We perform a computational analysis of the experimentally studied benzylium spectrum before extending the methods to a range of larger, closed-shell aromatic cations to determine the potential for this class of systems as diffuse interstellar band carriers. Methods. Density functional theory (DFT), time-dependant ((TD)DFT), and multi-configurational self-consistent field second-order perturbation theory (MRPT2) methods in concert with multidimensional FC analysis is used to model the benzylium spectrum. These methods are extended to larger closed-shell aromatic hydrocarbon cations derived from resonance-stabilized radicals, which are predicted to show strong S 0 → S n transitions in the visible region. The ionization energies of a range of these systems are also calculated by DFT. Results. The simulated benzylium spectrum was found to yield excellent agreement with the experimental spectrum showing an extended progression in a low frequency (510 cm −1 ) ring distortion mode. The FC progression was found to be significantly quenched in the larger species: 1-indanylium, 1-naphthylmethylium, and fluorenium. Excitation and ionization energies of the closed-shell cations were found to be consistent with diffuse interstellar band carriers, with the former lying in the visible range and the latter straddling the Lyman limit in the 13−14 eV range. Conclusions. Large closed-shell polycyclic aromatic hydrocarbon cations remain viable candidate carriers of the diffuse interstellar bands.

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Spectroscopic Identification of the Resonance-Stabilized cis- and trans-1-Vinylpropargyl Radicals

Cited by 45 publications

References 46 publications

The spectroscopy and thermochemistry of phenylallyl radical chromophores

The spectroscopy and thermochemistry of phenylallyl radical chromophores

Methyl rotor dependent vibrational interactions in toluene

On the electronic spectroscopy of closed-shell cations derived from resonance-stabilized radicals: Insights from theory and Franck-Condon analysis

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