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Updated: Jun 20, 2026

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Ortho-para mixing interaction in the vinyl radical detected by millimeter-wave spectroscopy
Keiichi Tanaka1, Masato Hayashi, Mitsuhiko Ohtsuki
1Department of Chemistry, Faculty of Sciences, Kyushu University, Hakozaki, Higashiku, Fukuoka 812-8581, Japan. ktanaka@chem.kyushu-univ.jp
Abstract:
Ortho-para mixing interaction due to the coupling of nuclear and electron spins was detected for the first time by millimeter-wave spectroscopy of the deuterated vinyl radical H(2)CCD. The ground state of H(2)CCD is split by the deuteron tunneling into two components 0(+) and 0(-) separated by DeltaE(0)=1186.794(16) MHz. Rotational levels in the 0(+) and 0(-) states, one being an ortho level and the other a para level, are coupled by the interaction expressed by 0(+/-)mid R:H(')mid R:0(-/+)=(deltaa(F)/2)S(I(1)-I(2)), where I(1) and I(2) are spins of the two protons and S is the electron spin. The deltaa(F) constant has been determined to be 68.06(52) MHz. The para to ortho conversion rate constant is predicted to be 1.2x10(5) s(-1) torr(-1).
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