Laser-induced excitation and dispersed fluorescence spectra of the ethoxy radical

Zhu, Xinming; Kamal, Mohammed M.; Misra, Prabhakar

doi:10.1088/0963-9659/5/6/027

Cited by 21 publications

(21 citation statements)

References 7 publications

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“…Relative energies for the photoproducts are determined using values in refs 52-54. than 49 and the dissociation threshold for C-O bond fission is about 900 cm -1 higher in ethoxy (31 620 cm -1 ). As a consequence, the highest-energy ethoxy transition seen by laserinduced fluorescence 26 at 32 139 cm -1 results in an excited state with five quanta in the C-O bond that lies only 520 cm -1 above the C 2 H 5 + O asymptote, whereas the ν 3 ) 6 level of the Ã 2 A 1 in methoxy lies 4738 cm -1 above the threshold for dissociation to CH 3 + O. 47 Thus, if the repulsive states correlating to this asymptote are similar to those in methoxy, considerably more excitation in the C-O stretch is needed in ethoxy for predissociation to occur, and the Franck-Condon factors for these transitions may simply be too small to be observable in our PFY spectrum.…”

Section: Discussionmentioning

confidence: 99%

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Photodissociation Dynamics of the Ethoxy Radical (C₂H₅O)

2000

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Photodissociation of the ethoxy (C 2 H 5 O) radical is investigated using photofragment translational spectroscopy. The ethoxy radical is generated by photodetachment of C 2 H 5 O -and subsequently dissociated by photon absorption in the range of 270-220 nm; no dissociation is seen at higher wavelengths. The photofragment yield (PFY) spectrum is structureless but exhibits abrupt increases in intensity at 260 and 225 nm. The product mass distribution shows that C 2 H 5 O dissociates into the vinyl radical (C 2 H 3 ) and H 2 O throughout the entire absorption band. We propose that these products are formed by isomerization and dissociation on electronically excited surfaces rather than by internal conversion to the ground state. The translational energy P(E T ) distributions for this channel are largely insensitive to photon energy. However, at the two highest photon energies (5.51 and 5.96 eV), a new feature appears at E T e 0.3 eV, which is assigned as production of an excited state of C 2 H 3 .

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Section: Discussionmentioning

confidence: 99%

“…No significant dissociation signal was observed in the region of 342-311 nm, where laser-induced fluorescence from the B 2 A′ f X 2 A′′ transition of C 2 H 5 O radicals was previously reported. 22,23,26 The photofragment flux increases around 260 and 225 nm.…”

Section: A Photofragment Yield (Pfy) Spectrum Of C 2 H 5 Omentioning

confidence: 99%

Photodissociation Dynamics of the Ethoxy Radical (C₂H₅O)

2000

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“…The jet-cooled LIF excitation spectrum of ethoxy has been reported by several groups [8][9][10] and selected vibrational bands in this spectrum were chosen to obtain the natural lifetimes. The lifetimes were measured using the following procedure.…”

Section: Methodsmentioning

confidence: 99%

Radiative and non-radiative decay of selected vibronic levels of the B state of alkoxy radicals

Gopalakrishnan

Miller

2003

Chemical Physics Letters

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“…An interesting question is the magnitude of the energy separation and the ordering of the two lowest states. TheÃ −X separation of the vibrationless levels (T 00 ) of ethoxy was found to be 364 cm −1 in DF spectroscopy 7,16 and 355(10) cm −1 in a photoelectron study. 17 Simulation of the origin band of theB −X LIF transition with rotational and fine-structure resolution was found to require a perpendicular transition type, 18 which implies that the ground electronic state is of A symmetry.…”

Section: Introductionmentioning

confidence: 95%

Rotationally resolved ${\tilde{B}} \leftarrow {\tilde{X}}$B̃←X̃ electronic spectra of the isopropoxy radical: A comparative study

Liu

Melnik

Miller

2013

The Journal of Chemical Physics

112

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The B̃-X̃ laser-induced-fluorescence spectrum of jet-cooled isopropoxy radical (i-C3H7O[middle dot]) has been recorded. Using an isolated state model the observed rotational and fine structure of the origin band has been well simulated to determine rotational constants for both the X̃ and B̃ states and the electron spin-rotation constants of the X̃ state. The line intensities are well simulated with a parallel transition type, requiring the same symmetry for the levels involved of each the X̃ and B̃ state, which confirms the previous suggestion that going from ethoxy (C2H5O[middle dot]) to isopropoxy, the energy ordering of the electron configurations with in- and out-of-plane half-filled p-orbitals of the oxygen atom is reversed and the ground vibronic symmetry changes from a" to a'. However, the observed spin-rotation coupling constants are not consistent with their predication from either semi-empirical theory or quantum chemical calculations. Additionally, the lack of observed transitions involving the out-of-plane transition moment component is not consistent with high level electronic structure calculations suggesting mixing of vibronic levels by strong spin-orbit coupling. A new twofold model has been developed that explicitly includes Coriolis and spin-orbit coupling between different vibronic levels. This model renders the discrepancy between theoretical and experimental spin-rotation constants moot. Moreover, it determines independently the contributions to the observed splitting between the lowest two levels, resulting from non-relativistic kinetic and Coulombic effects, and that due to the relativistic spin-orbit interaction. The experimental values show that these effects are comparable, but that the vibronic one is slightly more important. This result is at variance with state-of-the-art electronic structure calculations which otherwise do a remarkably good job of describing the ground state of isopropoxy.

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Laser-induced excitation and dispersed fluorescence spectra of the ethoxy radical

Cited by 21 publications

References 7 publications

Photodissociation Dynamics of the Ethoxy Radical (C₂H₅O)

Photodissociation Dynamics of the Ethoxy Radical (C₂H₅O)

Radiative and non-radiative decay of selected vibronic levels of the B state of alkoxy radicals

Rotationally resolved ${\tilde{B}} \leftarrow {\tilde{X}}$B̃←X̃ electronic spectra of the isopropoxy radical: A comparative study

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Laser-induced excitation and dispersed fluorescence spectra of the ethoxy radical

Cited by 21 publications

References 7 publications

Photodissociation Dynamics of the Ethoxy Radical (C2H5O)

Photodissociation Dynamics of the Ethoxy Radical (C2H5O)

Radiative and non-radiative decay of selected vibronic levels of the B state of alkoxy radicals

Rotationally resolved ${\tilde{B}} \leftarrow {\tilde{X}}$B̃←X̃ electronic spectra of the isopropoxy radical: A comparative study

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Photodissociation Dynamics of the Ethoxy Radical (C₂H₅O)

Photodissociation Dynamics of the Ethoxy Radical (C₂H₅O)