The helium(I) photoelectron spectrum of cyclopentadienone

Koenig, Thomas; Smith, Mary W.; Snell, W.

doi:10.1021/ja00462a031

Cited by 37 publications

(22 citation statements)

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“…Specifically, the ionisation energy for C 5 H 4 O obtained by interpreting the PIE curves (ca. 9.35 eV) was significantly smaller than that obtained previously in a pioneering experiment [13] (9.49 ± 0.02 eV). While the conditions used in our experiments are such that redshifts can be expected from thermal excitation of the neutrals, it was found that neither the character nor approximate onset of the PIE curves obtained for The stick spectrum comes from the Franck-Condon calculations discussed in the text, and is purely ab initio, in the sense that the origin peaks are not shifted from the positions calculated theoretically.…”

Section: Ipepico Studycontrasting

confidence: 67%

“…Those observed in typical aldehydes and ketones [12] are nπ * , resulting from the excitation of a non-bonding electron to the anti-bonding π orbital in the carbonyl group, whereas in C 5 H 4 =O, the lowest lying electronic transition is a ππ * transition localised largely within the ring. The earlier, pioneering photoelectron studies [13,14] identified the ground state of the C 5 H 4 =O cation as X + 2 A 2 and the first excited states of the cation as A + 2 B 2 and B + 2 B 1 , as would be predicted from the molecular orbital diagram in Figure 1, thereby tending to corroborate the proposal that the highest occupied molecular orbital of the neutral is a π orbital in the ring of a 2 symmetry. Cyclopentadienone not only presents an interesting chemical problem with intriguing electronic structure questions, it is also a system with practical importance.…”

Section: Introductionmentioning

confidence: 58%

“…cyclopentadienone was particularly sensitive to reactor temperature nor -significantly -was any appreciable isotope shift noted when fully deuterated o-phenylene sulphite was used as a precursor. Preliminary Franck-Condon simulations were broadly consistent with the original lowresolution He I photoelectron spectrum [13], so it is logical to attribute the difference to a calibration error. Since we have found a successful avenue for producing relatively large quantities of C 5 H 4 =O, it was felt worthwhile to carry out a careful study of its adiabatic ionisation potential and photoelectron spectrum.…”

Section: Ipepico Studymentioning

confidence: 70%

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The ionisation energy of cyclopentadienone: a photoelectron–photoion coincidence study

et al. 2015

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Imaging photoelectron photoion coincidence (iPEPICO) spectra of cyclopentadienone (C 5 H 4 =O and C 5 D 4 =O) have been measured at the Swiss Light Source Synchrotron (Paul Scherrer Institute, Villigen, Switzerland) at the Vacuum Ultraviolet (VUV) Beamline. Complementary to the photoelectron spectra, photoionisation efficiency curves were measured with tunable VUV radiation at the Chemical Dynamics Beamline at the Advanced Light ). For both experiments, molecular beams diluted in argon and helium were generated from the vacuum flash pyrolysis of o-phenylene sulphite in a resistively heated microtubular SiC flow reactor. The Franck-Condon profiles and ionisation energies were calculated at the CCSD(T) level of theory, and are in excellent agreement with the observed iPEPICO spectra. The ionisation energies of both cyclopentadienone-d 0 , IE(C 5 H 4 =O), and cyclopentadienoned 4 , IE(C 5 D 4 =O), were observed to be the same: 9.41 ± 0.01 eV. The mass-selected threshold photoelectron spectrum (ms-TPES) of cyclopentadienone reveals that the C=C stretch in the ground state of the cation is excited upon ionisation, supporting computational evidence that the ground state of the cation is X + 2 A 2 , and is in agreement with previous studies. However, the previously reported ionisation potential has been improved considerably in this work. In addition, since o-benzoquinone (o-O=C 6 H 4 =O and o-O=C 6 D 4 =O) is also produced in this process, its ms-TPES has been recorded. From the iPEPICO and photoionisation efficiency spectra, we infer an adiabatic ionisation energy of IE(o-O=C 6 H 4 =O) = 9.3 ± 0.1 eV, but the rather structureless spectrum indicates a strong change in geometry upon ionisation making this value less reliable.

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Section: Ipepico Studycontrasting

confidence: 67%

Section: Introductionmentioning

confidence: 58%

Section: Ipepico Studymentioning

confidence: 70%

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The ionisation energy of cyclopentadienone: a photoelectron–photoion coincidence study

et al. 2015

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“…The SAC-CI results for the ionized states are shown in Table 4, which also shows the experimental 13,14 and MINDO/3 calculated values. 14 The intensities of the ionization bands were calculated by monopole approximation.…”

Section: Ionized Ground and Excitedmentioning

confidence: 93%

“…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.…”

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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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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Photoelektronen‐Spektren und Moleküleigenschaften: Echtzeit‐Gasanalytik in strömenden Systemen

Bock¹,

Solouki²

1981

Angewandte Chemie

103

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Zur Analyse und zur Optimierung zahlreicher Gasreaktionen in strömenden Systemen hat sich die Photoelektronen‐Spektroskopie bestens bewährt: So gelingt es mit dieser Echtzeit‐Meßsonde bei den meisten Pyrolysen – in Millimol‐Ansätzen und innerhalb weniger Stunden –, die Temperaturen für die verschiedenen Zersetzungskanäle zu ermitteln, die Hauptprodukte zu charakterisieren und gegebenenfalls deren Ausbeute zu verbessern. Bei geeigneter Versuchsführung lassen sich kurzlebige und/oder reaktive Moleküle wie P2, Thioformaldehyd oder Silabenzol nachweisen. Von Vorteil ist die PE‐spektroskopische Gasanalytik insbesondere bei der Suche nach Heterogen‐Katalysatoren, die innerhalb eines Tages zwischen 300 und 1300 K mit Gasgemischen wechselnder Zusammensetzung getestet werden können. PE‐Spektrometer eignen sich zum ”︁on line„‐Anschluß an Rechner; tragbare Geräte für den Laborbetrieb befinden sich in Entwicklung.

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The helium(I) photoelectron spectrum of cyclopentadienone

Cited by 37 publications

References 3 publications

The ionisation energy of cyclopentadienone: a photoelectron–photoion coincidence study

The ionisation energy of cyclopentadienone: a photoelectron–photoion coincidence study

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

Photoelektronen‐Spektren und Moleküleigenschaften: Echtzeit‐Gasanalytik in strömenden Systemen

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