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Sub-Doppler infrared spectroscopy of propargyl radical (H2CCCH) in a slit supersonic expansion.
- Source :
-
Journal of Chemical Physics . 2015, Vol. 142 Issue 24, p1-10. 10p. 2 Diagrams, 2 Charts, 5 Graphs. - Publication Year :
- 2015
-
Abstract
- The acetylenic CH stretch mode (v1) of propargyl (H2CCCH) radical has been studied at sub-Doppler resolution (~60 MHz) via infrared laser absorption spectroscopy in a supersonic slit-jet discharge expansion, where low rotational temperatures (Trot = 13.5(4) K) and lack of spectral congestion permit improved determination of band origin and rotational constants for the excited state. For the lowest J states primarily populated in the slit jet cooled expansion, fine structure due to the unpaired electron spin is resolved completely, which permits accurate analysis of electron spin-rotation interactions in the vibrationally excited states (εaa = -518.1(1.8), εbb = -13.0(3), εcc = -1.8(3) MHz). In addition, hyperfine broadening in substantial excess of the sub-Doppler experimental linewidths is observed due to nuclear spin-electron spin contributions at the methylenic (--CH2) and acetylenic (--CH) positions, which permits detailed modeling of the fine/hyperfine structure line contours. The results are consistent with a delocalized radical spin density extending over both methylenic and acetylenic C atoms, in excellent agreement with simple resonance structures as well as ab initio theoretical calculations. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00219606
- Volume :
- 142
- Issue :
- 24
- Database :
- Academic Search Index
- Journal :
- Journal of Chemical Physics
- Publication Type :
- Academic Journal
- Accession number :
- 103636192
- Full Text :
- https://doi.org/10.1063/1.4922931