Communication: A vibrational study of propargyl cation using the vacuum ultraviolet laser velocity-map imaging photoelectron method
- Department of Chemistry, University of California, Davis, California 95616 (United States)
By employing the vacuum ultraviolet (VUV) laser velocity-map imaging photoelectron (VUV-VMI-PE) method, we have obtained a vibrationally resolved photoelectron spectrum of gaseous propargyl radical [C{sub 3}H{sub 3}(X{sup 2}B{sub 1})] in the energy range of 0-4600 cm{sup -1} above its ionization energy. The cold C{sub 3}H{sub 3} radicals were produced from a supersonically cooled radical beam source based on 193 nm ArF photodissociation of C{sub 3}H{sub 3}Cl. The VUV-VMI-PE spectrum of C{sub 3}H{sub 3} thus obtained reveals a Franck-Condon factor (FCF) pattern with a highly dominant origin band along with weak vibrational progressions associated with excitations of the C-C {nu}{sub 5}{sup +}(a{sub 1}) and C{identical_to}C {nu}{sub 3}{sup +}(a{sub 1}) symmetric stretching modes and the CCH {nu}{sub 7}{sup +}(b{sub 1}) out-of-plane bending mode of C{sub 3}H{sub 3}{sup +}(X{sup 1}A{sub 1}). The {nu}{sub 5}{sup +}(a{sub 1}) vibrational frequency of 1120 cm{sup -1} determined in the present study is lower than the value deduced from the recent Ar-tagged infrared photodissociation study by 102 cm{sup -1}, confirming the highly accurate vibrational frequency predictions obtained by the most recent state-of-the-art ab initio quantum calculations. The observation of the FCF disallowed {nu}{sub 7}{sup +}(b{sub 1}) mode is indicative of vibronic interactions. The discrepancy observed between the FCF pattern determined in the present study and that predicted by a recent high-level quantum theoretical investigation can be taken as evidence that the potential energy surfaces used in the latter theoretical study are in need of improvement in order to provide a reliable FCF prediction for the C{sub 3}H{sub 3}/C{sub 3}H{sub 3}{sup +} photoionization system.
- OSTI ID:
- 22099065
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 16 Vol. 137; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
Similar Records
Photoelectron spectrum of the propargyl radical in a supersonic beam
High resolution pulsed field ionization-photoelectron study of CO{sub 2}{sup +}(X {sup 2}{pi}{sub g}) in the energy range of 13.6-14.7 eV
Related Subjects
74 ATOMIC AND MOLECULAR PHYSICS
ARGON FLUORIDES
CATIONS
DISSOCIATION
EXCITATION
FAR ULTRAVIOLET RADIATION
FORECASTING
INTERACTIONS
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
PHOTOLYSIS
PHOTON-MOLECULE COLLISIONS
PROPARGYL RADICALS
SPECTRA
SURFACES
VIBRATIONAL STATES