Browsing by Author "Mizoguchi, Asao"

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Detection of Microwave Transitions between Ortho and Para States in a Free Isolated Molecule
(2017-10-25)
Kanamori, Hideto
;
Dehghani, Zeinab. T.
;
Mizoguchi, Asao
;
Endo, Yasuki
;
應用化學系
Microwave transitions between the ortho and para states of the S2Cl2 molecule in a free isolated condition are observed for the first time. In the theoretical treatment, we derive eigenfunctions of an effective Hamiltonian including the ortho-para interaction to calculate the intensities and frequencies of forbidden ortho-para transitions in the cm-wave region and pick up some promising candidates for the spectroscopic detection. In the experiment, transitions of the S2Cl2 molecule under a supersonic jet condition are observed with a Fourier transform microwave spectrometer. Seven hyperfine resolved rotational transitions including the lowest rotational level are detected as the ortho-para transitions at the predicted frequencies within the experimental errors. The observed intensities are about 10(-3) times the allowed transitions, which are consistent with the predictions based on the intensity-borrowing model. This result suggests that the orthopara conversion of this molecule occurs in a few thousand years through spontaneous emission even in a circumstance where molecular collisions occur rarely like in interstellar space.