Ionization photophysics and Rydberg spectroscopy of diacetylene

Martin Schwell, Yves Bénilan, Nicolas Fray, Marie Claire Gazeau, Et-touhami Es-sebbar, François Gaie-Levrel, Norbert Champion, Sydney Sydney Leach

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Photoionization of diacetylene was studied using synchrotron radiation over the range 8-24 eV, with photoelectron-photoion coincidence (PEPICO) and threshold photoelectron-photoion coincidence (TPEPICO) techniques. Mass spectra, ion yields, total and partial ionization cross-sections were measured. The adiabatic ionization energy of diacetylene was determined as IE ad=(10.17±0.01) eV, and the appearance energy of the principal fragment ion C4H+ as AE=(16.15±0.03) eV. Calculated appearance energies of other fragment ions were used to infer aspects of dissociation pathways forming the weaker fragment ions C+ 4, C3H+, C+3 and C 4H+. Structured autoionization features observed in the PEPICO spectrum of diacetylene in the 11-13 eV region were assigned to vibrational components of three new Rydberg series, R1(nsσg, n=4-11), R2(ndσg, n=4-7) and R3(ndδg, n=4-6) converging to the A2Πu state of the cation, and to a new series R01(nsσg, n=3) converging to the B' 2Σ+u state of the cation. The autoionization mechanisms and their consistence with specific selection rules are discussed. © 2012 Taylor and Francis.
Original languageEnglish (US)
Pages (from-to)2843-2856
Number of pages14
JournalMolecular Physics
Issue number21-22
StatePublished - Jul 11 2012

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01

ASJC Scopus subject areas

  • Molecular Biology
  • Physical and Theoretical Chemistry
  • Biophysics
  • Condensed Matter Physics


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