High-resolution velocity-map-imaging photoelectron spectroscopy of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi mathvariant="normal">O</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math>photodetachment fine-structure transitions

Cavanagh, Steven; Gibson, S. T.; Gale, Mary-Anne; Dedman, Colin J; Roberts, E; Lewis, B. R.

doi:10.1103/physreva.76.052708

Cited by 98 publications

(52 citation statements)

References 37 publications

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“…The circularisation method used in this study was designed by Lawrance and Gascooke 26 and has been used in previous VMI studies. 27,28 The process involves partitioning the image into wedges, each having a fixed angle and centred on the image centre. One wedge is taken as a reference wedge to which all other wedges can be compared.…”

Section: Experimental Methodsmentioning

confidence: 99%

Spectroscopic observation of gold-dicarbide: Photodetachment and velocity map imaging of the AuC2 anion

Visser

Addicoat

Gascooke

et al. 2013

The Journal of Chemical Physics

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Photoelectron spectra following photodetachment of the gold dicarbide anion, ${\rm AuC}_2^ - $ AuC 2−, have been recorded using the velocity map imaging technique at several excitation wavelengths. The binding energy spectra show well-defined vibrational structure which, with the aid of computational calculations and Franck-Condon simulations, was assigned to a progression in the Au–C stretching mode, ν3. The experimental data indicate that the features in the spectrum correspond to a 2A′ ← 3A′ transition, involving states which we calculate to have bond angles ∼147° but with a low barrier to linearity.

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Section: Experimental Methodsmentioning

confidence: 99%

Spectroscopic observation of gold-dicarbide: Photodetachment and velocity map imaging of the AuC2 anion

Visser

Addicoat

Gascooke

et al. 2013

The Journal of Chemical Physics

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“…Several alternative VMI designs with excellent focusing capability for photoelectrons have been reported in the literature (55)(56)(57). The key changes made in these designs include adding a fourth electrode whose voltage is adjusted to optimize focus (55,57) and increasing the total length of the VMI stack (56).…”

Section: Methodsmentioning

confidence: 99%

“…The key changes made in these designs include adding a fourth electrode whose voltage is adjusted to optimize focus (55,57) and increasing the total length of the VMI stack (56). Increasing the length of the VMI lens along the electron flight axis can significantly improve its focusing ability, as the volume of the interaction region is smaller relative to the size of the lens.…”

Section: Methodsmentioning

confidence: 99%

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Isomer-specific vibronic structure of the 9-, 1-, and 2-anthracenyl radicals via slow photoelectron velocity-map imaging

Weichman

DeVine

Levine

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Polycyclic aromatic hydrocarbons, in various charge and protonation states, are key compounds relevant to combustion chemistry and astrochemistry. Here, we probe the vibrational and electronic spectroscopy of gas-phase 9-, 1-, and 2-anthracenyl radicals (C 14 H 9 ) by photodetachment of the corresponding cryogenically cooled anions via slow photoelectron velocity-map imaging (cryo-SEVI). The use of a newly designed velocity-map imaging lens in combination with ion cooling yields photoelectron spectra with <2 cm −1 resolution. Isomer selection of the anions is achieved using gasphase synthesis techniques, resulting in observation and interpretation of detailed vibronic structure of the ground and lowest excited states for the three anthracenyl radical isomers. The groundstate bands yield electron affinities and vibrational frequencies for several Franck-Condon active modes of the 9-, 1-, and 2-anthracenyl radicals; term energies of the first excited states of these species are also measured. Spectra are interpreted through comparison with ab initio quantum chemistry calculations, Franck-Condon simulations, and calculations of threshold photodetachment cross sections and anisotropies. Experimental measures of the subtle differences in energetics and relative stabilities of these radical isomers are of interest from the perspective of fundamental physical organic chemistry and aid in understanding their behavior and reactivity in interstellar and combustion environments. Additionally, spectroscopic characterization of these species in the laboratory is essential for their potential identification in astrochemical data.polycyclic aromatic hydrocarbons | anion photoelectron spectroscopy | velocity-map imaging | vibronic structure P olycyclic aromatic hydrocarbons (PAHs) are an important class of species in many areas of chemistry. They are major components in coal (1) and in soot formed from combustion of organic matter (2, 3). PAHs are therefore common environmental pollutants and have well-documented mutagenic and carcinogenic biological activity (4, 5). PAHs are also believed to be abundant in the interstellar medium (6) and may be carriers of the anomalous IR emission bands (7-9). Recent molecular beam studies indicate that PAH growth can proceed through cold collisions of smaller hydrocarbons under interstellar conditions (10, 11). Individual PAH molecules can subsequently provide nucleation sites for amorphous graphitic grains (9). Interstellar PAHs and their clusters therefore bridge the gap between small carbonaceous molecules and larger particles, analogous to their role in soot condensation in combustion environments (12).In space, PAH species are likely to exist as an equilibrium of neutral and ionic charge states, with varying degrees of hydrogenation and dehydrogenation (13-15). Models of dense interstellar clouds find that anionic PAHs are the major carriers of negative charge, rather than free electrons (16). Closed-shell, singly deprotonated PAH carbanions have large electron affinities compared with ...

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“…The electron kinetic energy scale was calibrated by measuring the photoelectron spectra of H − and O − . [22][23][24] In this experiment, 15 000-30 000 laser shots were needed to produce an image with good signal to noise. Photoelectron images were analyzed using the Basis Set Expansion, BASEX, Abel transformation method to obtain photoelectron spectra and photoelectron angular distributions, PADs.…”

mentioning

confidence: 99%

Communication: Photoelectron angular distributions of CH− reveal a temporary anion state

Bandyopadhyay

Pruitt

Goebbert

2013

The Journal of Chemical Physics

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Photoelectron imaging has broadened the scope of traditional photoelectron spectroscopy by combining a simultaneous photoelectron angular distribution, PAD, measurement with kinetic energy analysis. A fundamental understanding of PADs has been largely limited to simple atomic systems. However, a new model has recently been developed that predicts PADs as a function of electron kinetic energy for a simple linear combination of s and p atomic orbitals. We used CH− to test this model by acquiring PADs in a photoelectron imaging spectrometer at wavelengths from 600 to 355 nm. The PADs for electron detachment from the HOMO (1π) of CH− fit model predictions. However, the PADs associated with detachment from the HOMO-1 (3σ) orbital exhibit anomalous behavior at low electron kinetic energies because of a resonant process that arises from a previously undetected excited state of CH−.

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High-resolution velocity-map-imaging photoelectron spectroscopy of theO−photodetachment fine-structure transitions

Cited by 98 publications

References 37 publications

Spectroscopic observation of gold-dicarbide: Photodetachment and velocity map imaging of the AuC2 anion

Spectroscopic observation of gold-dicarbide: Photodetachment and velocity map imaging of the AuC2 anion

Isomer-specific vibronic structure of the 9-, 1-, and 2-anthracenyl radicals via slow photoelectron velocity-map imaging

Communication: Photoelectron angular distributions of CH− reveal a temporary anion state

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