The spectroscopic characterization of the methoxy radical. III. Rotationally resolved $\skew3\tilde{A}^2A_1\text{&amp;#x2013;}\skew3\tilde{X}^2E$Ã2A1–X̃2E electronic and $\skew3\tilde{X}^2E$X̃2E submillimeter wave spectra of partially deuterated CH2DO and CHD2O radicals

Melnik, Dmitry G.; Liu, Jinjun; Chen, Ming-Wei; Miller, Terry A.; Curl, R. F.

doi:10.1063/1.3615724

Cited by 21 publications

(23 citation statements)

References 56 publications

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“…In discussing the experimental value of the vibronic angular momentum it is useful to recall its definition 14 in terms of components of the electronic and vibronic angular momentum along the inertial axis, α,…”

Section: A Ground State Rotational Constantsmentioning

confidence: 99%

“…The second effect of the chemical substitution is a rather dramatic rotation of the PAS system, and correspondingly the top axis with respect to the IAS axis system, 14,56 resulting in redistribution of the transition moment along the PAS axes contained in the plane of symmetry of the molecule (bc-plane in the PAS of the isopropoxy). Such a redistribution can be simply described by the rotation of the transition moment by the angle 90 • − θ between the c axis and and the CO bond.…”

Section: Transition Intensitiesmentioning

confidence: 99%

“…Most recently, the submillimeter-wave, LIF, and SEP spectra of the asymmetrically deuterated methoxy radicals (CH 2 DO and CHD 2 O) have been recorded and analyzed. 14 Global fitting of the spectra and analysis of the isotopic relations of all four isotopologues provide valuable information of the partial breaking of vibronic symmetry due to asymmetric deuteration. It is found that for both isotopologues, the asymmetric deuteration splits the vibrationless level of the ground electronic state into two levels, with a and a symmetries, respectively.…”

Section: Introductionmentioning

confidence: 99%

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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

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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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Section: A Ground State Rotational Constantsmentioning

confidence: 99%

Section: Transition Intensitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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

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112

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“…55 TheÃ states are therefore thermally populated and impact the reactivity of the radicals. The energies of these states have been probed by dispersed fluorescence spectroscopy from higher-lying excited states 25,26,29,34,44,50,55 or by photoelectron (PE) spectroscopy of the closed shell anionic precursors, 36,57,59,62,63 the latter of which is lower resolution but offers the advantage of mass selectivity.…”

Section: Introductionmentioning

confidence: 99%

Probing alkenoxy radical electronic structure using anion PEI spectroscopy

Patros

Mann

Dobulis

et al. 2019

The Journal of Chemical Physics

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Photoelectron imaging spectra of three alkenoxide radical anions (3-buten-1-oxide, 3-buten-2-oxide, and 2-propenoxide) are presented and analyzed with supporting results of density functional theory calculations. In all spectra, intense detachment features are observed at approximately 2 eV electron binding energy, which is similar to the electron affinities of saturated neutral alkoxy radicals [Ramond et al., J. Chem. Phys. 112, 1158]. Photoelectron angular distributions suggest the presence of several overlapping transitions which are assigned to theX andÃ states of multiple energetically competitive conformers. The term energy of theÃ state of the 2-propenoxy radical, 0.17 eV, is higher than that of 3-buten-2-oxy (0.13 eV) and 3-buten-1-oxy (0.05 eV) radicals. Comparing the butenoxy radicals, we infer that stronger interactions between the non-bonding O 2p orbitals and the π bond increase the splitting between the ground and the first excited state in the 3-buten-2-oxy radical relative to the 3-buten-1-oxy radical.

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“…[37,38] Rotationally resolved spectra have been obtained by a number of techniques including far-infrared laser magnetic resonance (LMR), [39,40] microwave studies, [41,42,43] and LIF. [44,45,46] Many of these experiments have also been applied to the deuterated species. [24,28,47,38] An experimental data fit yields a JTSE of 419 cm −1 .…”

Section: Introductionmentioning

confidence: 99%

Quantifying the effects of higher order coupling terms on fits using a second order Jahn-Teller Hamiltonian

Tran

Stanton

Miller

2018

Journal of Molecular Spectroscopy

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The limitations associated with the common practice of fitting a quadratic Hamiltonian to vibronic levels of a Jahn-Teller system have been explored quantitatively. Satisfactory results for the prototypicalX 2 E state of Li 3 are obtained from fits to both experimental spectral data and to an "artificial" spectrum calculated by a quartic Hamiltonian which accurately reproduces the adiabatic potential obtained from state-of-the-art quantum chemistry calculations. However the values of the Jahn-Teller parameters, stabilization energy, and pseudo-rotation barrier obtained from the quadratic fit differ markedly from those associated with the ab initio potential. Nonetheless the RMS deviations of the fits are not strikingly different. Guidelines are suggested for comparing parameters obtained from fits to experiment to those obtained by direct calculation, but a principal conclusion of this work is that such comparisons must be done with a high degree of caution.

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The spectroscopic characterization of the methoxy radical. III. Rotationally resolved $\skew3\tilde{A}^2A_1\text{–}\skew3\tilde{X}^2E$Ã2A1–X̃2E electronic and $\skew3\tilde{X}^2E$X̃2E submillimeter wave spectra of partially deuterated CH2DO and CHD2O radicals

Cited by 21 publications

References 56 publications

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

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

Probing alkenoxy radical electronic structure using anion PEI spectroscopy

Quantifying the effects of higher order coupling terms on fits using a second order Jahn-Teller Hamiltonian

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