title: Fourier transform microwave spectroscopy of CH(2)CFO.
abstract: Rotational spectra of the CH(2)CFO radical in the (2)A(") ground state with resolved fine and hyperfine structures have been observed for the first time by Fourier transform microwave spectroscopy. Rotational transitions are analyzed using the ordinary rigid asymmetric top Hamiltonian for doublet species with three nuclear spins. Seventeen molecular constants including the fine and hyperfine coupling constants have been determined. The CH(2)CFO radical is confirmed to be a planer molecule in the ground electronic state since it has a small positive inertial defect. From the hyperfine coupling constants of protons, the unpaired electron density on the CH(2) carbon atom is estimated to be about 85%. Thus, the formylmethyl-type resonance form (CH(2)CF=O) is a dominant structure in the ground electronic state, and fluorine substitution has negligible effect on the C-C-O pi conjugate system.
authors.affiliation: Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Watanabe
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sumiyoshi
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Endo