Threshold resonances in electron photodetachment spectra. Structural evidence for dipole-supported states

Marks, Jeffrey M.; Comita, Paul B.; Brauman, John I.

doi:10.1021/ja00298a053

Cited by 50 publications

(55 citation statements)

References 3 publications

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“…The orbital energy of the LUMO is negative (-0.271 eV), suggesting that the electron affinity of o-BQ is largely positive. The experimental results, 16 along with our SAC-CI results, support this supposition, as seen later. Two π* orbitals (#46, 7b 1 and #61, 7a 2 ) exist in the unoccupied higher energy region.…”

Section: Singlet Excited Statessupporting

confidence: 86%

“…13,14 Koenig et al 13 observed the photoelectron spectrum of o-BQ for the lowest four states; however, these ionized states were not assigned. Schang et al 14 Few studies on the electronic states of the o-BQ anion radical (o-BQ -) can be found, except for an experimental study by Marks et al, 16 which approximately assigned the adiabatic electron affinity as 1.62 eV on the basis of electron photodetachment spectroscopy. They also observed the dipole-bound excited states of o-BQ -below the electron-detachment threshold.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ground and Excited States of Singlet, Cation Doublet, and Anion Doublet States of o-Benzoquinone: A Theoretical Study

et al. 2007

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The singlet excited states and doublet ionized/electron-attached states of o-benzoquinone (o-BQ) were studied by the symmetry adapted cluster (SAC)/ SAC-configuration interaction (SAC-CI) method, and the corresponding spectral bands were assigned. The calculated transition energies reasonably reproduced the experimental spectra with the mean error of about 0.2 eV, except for the 1 1 A 1 states, whose disagreement may be attributed to involvement of the shoulder peak of this state in the intense peak at approximately 6.2 eV. For the singlet states, the lowest four excited states were assigned to n, and π + -π + * ( 1 A 1 ) in order of increasing energy, and the intense band at approximately 6.2 eV in the experimental spectra was assigned to the 1 B 2 state in our calculations. For the cation doublet states, the lowest four states were assigned to n + ( 2 A 1 ), π -( 2 A 2 ), n -( 2 B 2 ), and π + ( 2 B 1 ) in order of increasing energy. Shake-up ionized states appeared in the energy region higher than 16 eV. For the anion doublet states, the ground state was 2 B 1 , and five valence excited states were calculated within 4.0 eV above the anion ground state. The adiabatic electron affinity was calculated to be 1.63 eV, which is in very good agreement with the corresponding experimental value (1.62 eV). The use of Koopmans' theorem does not reproduce this energy order for either the singlet or the doublet states. We showed that, as in the case of p-BQ (J. Phys. Chem. A 2002, 106, 3838), electron correlation is essential in the description of the excited states of o-BQ.

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Section: Singlet Excited Statessupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Ground and Excited States of Singlet, Cation Doublet, and Anion Doublet States of o-Benzoquinone: A Theoretical Study

et al. 2007

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“…21 Finally, Brauman and co-workers have reported low resolution total photodetachment cross sections with photon energies up to ~4.6 eV, identifying two broad maxima centered at ~3.0 eV and ~4.1 eV, as well as the onset of an intense band starting at ~4.4 eV. 25,26 5 pBQ has also been the subject of a number of electron attachment and transmission studies, which have identified at least three resonances centered at 0.7 eV, 1.4 eV and ~2.0 eV above the ground state of the neutral, with the latter producing radical anions that survive for at least several microseconds. 8,12-14 Although some vibrational structure could be discerned in these experiments, on the whole, the bands are very broad and overlapping.…”

Section: Introductionmentioning

confidence: 99%

Anion Resonances of para-Benzoquinone Probed by Frequency-Resolved Photoelectron Imaging

et al. 2014

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract:The resonant attachment of a free electron to a closed shell neutral molecule, and the interplay between the following electron detachment and electronic relaxation channels represents a fundamental but common process throughout chemical and biochemical systems. The new methodology of anion frequency-resolved photoelectron imaging is detailed and used to map-out molecular excited state dynamics of gas-phase para-benzoquinone, which is the electron accepting moiety in many biological electron-transfer chains. Three-dimensional spectra of excitation energy, electron kinetic energy and electron ejection anisotropy reveal clear fingerprints of excited and intermediate state dynamics. The results show that many of the excited states are strongly coupled, providing a route to forming the ground state radical anion, despite the fact that the electron is formally unbound in the excited states. The relation of our method to electron impact attachment studies and the key advantages, including the extension to time-resolved dynamics and to larger molecular systems is discussed.

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“…2 Therefore the radical anion of PBQ (also called the semiquinone radical anion) has been investigated quite thoroughly by different spectroscopic techniques. Its excited state structure has been probed by different methods, both in the gas [3][4][5][6] and condensed phases. [7][8][9][10] With regard to the vibrational structure of PBQ À , several groups have reported and assigned (resonance)…”

Section: Introductionmentioning

confidence: 99%

Vibronic spectra of the p-benzoquinone radical anion and cation: a matrix isolation and computational study

Piech

Bally

Ichino

et al. 2014

Phys. Chem. Chem. Phys.

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The electronic and vibrational absorption spectra of the radical anion and cation of p-benzoquinone (PBQ) in an Ar matrix between 500 and 40 000 cm À1 are presented and discussed in detail. Of particular interest is the radical cation, which shows very unusual spectroscopic features that can be understood in terms of vibronic coupling between the ground and a very low-lying excited state. The infrared spectrum of PBQ + exhibits a very conspicuous and complicated pattern of features above 1900 cm A notable exception is the antisymmetric CQO stretching vibration, which contributes significantly to the vibronic coupling, but has nevertheless quite small intensity in the cation spectrum. This surprising feature is rationalized on the basis of a simple perturbation analysis.

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Threshold resonances in electron photodetachment spectra. Structural evidence for dipole-supported states

Cited by 50 publications

References 3 publications

Ground and Excited States of Singlet, Cation Doublet, and Anion Doublet States of o-Benzoquinone: A Theoretical Study

Ground and Excited States of Singlet, Cation Doublet, and Anion Doublet States of o-Benzoquinone: A Theoretical Study

Anion Resonances of para-Benzoquinone Probed by Frequency-Resolved Photoelectron Imaging

Vibronic spectra of the p-benzoquinone radical anion and cation: a matrix isolation and computational study

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