Variable angle photoelectron spectroscopy of the fluoroethylenes

Sell, Jeffrey A.; Kuppermann, Aron

doi:10.1063/1.438254

Cited by 32 publications

(31 citation statements)

References 70 publications

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“…18 Ab initio calculations suggest that all four molecules remain planar upon ionization, but when Franck-Condon factors are considered, loss of planarity is discovered for 1,1-C 2 H 2 F 2 as a result of ionization from the C=C double bond. The successful application of fitting the ground state band with the Franck-Condon intensities and apparent similarities between the PES 1,3,5,6 and TPES of this work indicates that no autoionization effects are seen. Locht et al 5,6 reported a large intensity ratio for the excited vs. ground electronic state bands in the TPES, whereas we find that the ground state bands have comparable intensities to the first excited state band in the TPES.…”

Section: Introductionmentioning

confidence: 87%

“…Although some vibrational structure has been observed in the ground-state PE band by others, 1,3 this is the first high resolution TPES of this molecule reported in the literature. The (4a ) 2 HOMO of the neutral C S C 2 HF 3 molecule has C=C π orbital character, and the cation electronic ground state has the term symbolX 2 A .…”

Section: Trifluoroethenementioning

confidence: 99%

“…17 The difference in the extent of coupling and therefore the amount of twist seen could be due, in part, to the larger difference in energy 31 between theX andÃ states of 1,1-C 2 H 2 F 2 + of 4.31 eV compared with that of C 2 H 4 + of 2.31 eV. 3 The second of these minor peaks at 10.382 eV lies 637 cm −1 above the band origin and is also well reproduced in the Franck-Condon fitting by the ν 12 mode of b 1 symmetry at 628 cm −1 . This is the only mode within 50 cm…”

Section: 1-difluoroethenementioning

confidence: 99%

“…The TPES of C 2 F 4 , recorded by Jarvis et al, 7 significantly improved upon the resolution of the early work by Sell and Kuppermann. 3 Lately, the HeI PES of C 2 F 4 has been studied by Eden et al,8 with an even higher resolution and signal-tonoise ratio.…”

Section: Introductionmentioning

confidence: 99%

“…1,2 The earliest comprehensive study of the ionization properties of fluorinated ethene molecules was reported by Sell and Kuppermann,3 who studied the photoelectron angular distributions in the ground and excited state bands of the HeI photoelectron spectra (PES) of C 2 H 4−n F n (n = 0-4) molecules. The HeII PES have been recorded and interpreted, among others, by Bieri et al 1 with many body Green's function calculations.…”

Section: Introductionmentioning

confidence: 99%

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Vibrational and electronic excitations in fluorinated ethene cations from the ground up

Harvey

Hemberger

Bodi

et al. 2013

The Journal of Chemical Physics

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Valence threshold photoelectron spectra of four fluorinated ethenes; C 2 H 3 F, 1,1-C 2 H 2 F 2 , C 2 HF 3 , and C 2 F 4 were recorded at the Swiss Light Source with 0.002 eV resolution. The adiabatic ionization energies were found to be 10.364 ± 0.007, 10.303 ± 0.005, 10.138 ± 0.007, and 10.110 ± 0.009 eV, respectively. The electronic ground state of each cation shows well-resolved multi-component vibrational progressions, the dominant transitions being in the C=C stretching mode. Density functional theory based Franck-Condon simulations are used to model the vibrational structure and assign the spectra, sometimes revising previous assignments. An additional vibrational progression in the first photoelectron band of 1,1-C 2 H 2 F 2 indicates that the ground electronic state of the molecular ion is no longer planar. It is shown that ab initio vibrational frequencies together with the observed vibrational spacings do not always suffice to assign the spectra. In addition to symmetry rules governing the transitions, it is often essential to consider the associated Franck-Condon factors explicitly. Ionization to higher lying excited valence electronic states were also recorded by threshold ionization up to 23 eV photon energy. Equation-of-motion coupled cluster with single and double substitutions for ionization potential (EOM-IP-CCSD/cc-pVTZ) calculations confirmed historic electronic state assignments, and untangled the ever more congested spectra with increasing F-substitution. Previous attempts at illuminating the intriguing dissociative photoionization mechanism of fluorinated ethenes are reconsidered in view of new computational and experimental results. We show how non-statistical F-atom loss from C 2 H 3 F + is decoupled from the ground state dissociation dynamics in the energy range of itsC state. Both the statistical and the non-statistical dissociation processes are mediated by a plethora of conical intersections.

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Section: Introductionmentioning

confidence: 87%

Section: Trifluoroethenementioning

confidence: 99%

Section: 1-difluoroethenementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Vibrational and electronic excitations in fluorinated ethene cations from the ground up

Harvey

Hemberger

Bodi

et al. 2013

The Journal of Chemical Physics

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Symmetriebrechung und Nicht‐Born‐Oppenheimer‐Effekte in Radikalkationen

et al. 1983

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Die verschiedenen elektronischen Zustinde, in denen Molekule existieren konnen, werden oft als voneinander unabhlngig betrachtet. Thematik des vorliegenden Aufsatzes ist es, die Grenzen dieser Annahme zu verdeutlichen, namlich die Wechselwirkung zwischen verschiedenen elektronischen Molekiilzustinden durch die Kernbewegung. Diese Wechselwirkung kann mehrere wichtige Konsequenzen haben, von denen zwei im Detail diskutiert werden. Die erste ist eine Verzerrung des Kerngeriistes des Molekiils, was zu einer Symmetrieerniedrigung in angeregten oder ionischen Zustlnden gegenuber dem Grundzustand der neutralen Spezies fuhrt. Allgemeine Merkmale dieser Symmetrieerniedrigung werden anhand typischer Beispiele interpretiert. Die andere Konsequenz der Wechselwirkung ist die Moglichkeit, daB die Atomkerne wihrend ihrer Schwingungsbewegung zwischen verschiedenen Potentialfllchen des Molekuls hin-und herspringen (Nicht-Born-Oppenheimer-Effekte). Das Wesen dieses Verhaltens wird untersucht, und es wird gezeigt, daB das ,,Spingen" sehr schnell vor sich gehen und die Kernbewegung vollstandig beherrschen kann. Zur Veranschaulichung unserer allgemeinen Ideen benutzen wir die Photoelektronen-Spektren von Ethylen und verwandten Verbindungen und weisen in ihnen das Auftreten starker Nicht-Born-Oppenheimer-Effekte nach. Es stellt sich heraus, daB hier das Franck-Condon-Prinzip bei der Analyse der Schwingungsstruktur versagt.

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Symmetry Breaking and Non‐Born‐Oppenheimer Effects in Radical Cations

Köppel

Cederbaum

Domcke

et al. 1983

Angew. Chem. Int. Ed. Engl.

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The various electronic states in which molecules can exist are often considered to be independent. In this article we turn our attention to the limitations of this assumption, namely the interaction between different electronic states through the nuclear motion. This interaction can have several important consequences, two of which are discussed in some detail. One is a distortion of the molecular framework, leading to a lowering of the symmetry of a molecule in excited or ionic states compared to the neutral ground state. General aspects of this symmetry lowering are outlined and interpreted with the aid of typical examples. The other consequence considered is the ability of the nuclei to "jump" between different molecular potential energy surfaces (non-Born-Oppenheimer effects). The nature of this behavior is analyzed and it is argued that the "jumping" can be very fast and efficient, dominating completely the nuclear motion. To exemplify our general ideas we refer to the photoelectron spectra of ethylene and related compounds and demonstrate that they are governed by strong non-Born-Oppenheimer effects. It emerges that the Franck-Condon principle fails in the analysis of their vibronic structure.

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Variable angle photoelectron spectroscopy of the fluoroethylenes

Cited by 32 publications

References 70 publications

Vibrational and electronic excitations in fluorinated ethene cations from the ground up

Vibrational and electronic excitations in fluorinated ethene cations from the ground up

Symmetriebrechung und Nicht‐Born‐Oppenheimer‐Effekte in Radikalkationen

Symmetry Breaking and Non‐Born‐Oppenheimer Effects in Radical Cations

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