title: Laboratory detection of a new interstellar free radical CH2CN(2B1).
abstract: An asymmetric-top free radical CH2CN, which as a 2B1 ground state, was detected for the first time by laboratory microwave spectroscopy.  The radical was produced in a free-space absorption cell by a DC glow discharge in pure CH3CN gas.  About 60 fine-structure components were observed for the N = 11-10 to 14-13 a-type rotational transitions in the frequency region of 220-260 GHz, and many hyperfine resolved components for the N = 4-3 and 5-4 transitions in the 80 and 100 GHz regions, respectively.  The molecular constants, including the rotational constants, centrifugal distortion constants, and spin-rotation coupling constants with centrifugal distortion correction terms were determined from the fine-structure resolved transitions, and the hyperfine coupling constants due to the hydrogen and nitrogen nuclei were obtained from the low-N transitions.  As a result we assigned U100602 and U80484 from Sgr B2, and U40240 and U20120 from TMC-1, to the N = 5-4, 4-3, 2-1, and 1-0 transitions with K-1 = 0 of the CH2CN radical.
authors.affiliation: Department of Astrophysics, Nagoya University.
authors.forename: S
authors.initials: S
authors.lastname: Saito
authors.forename: S
authors.initials: S
authors.lastname: Yamamoto
authors.forename: W M
authors.initials: WM
authors.lastname: Irvine
authors.forename: L M
authors.initials: LM
authors.lastname: Ziurys
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: M
authors.initials: M
authors.lastname: Ohishi
authors.forename: N
authors.initials: N
authors.lastname: Kaifu
mesh_terms: D000097:Acetonitriles / Q000032:analysis*; D055580:Astronomical Phenomena; D001256:Astronomy; D055598:Chemical Phenomena; D002621:Chemistry; D005118:Extraterrestrial Environment; D005609:Free Radicals / Q000032:analysis*; D006838:Hydrocarbons / Q000032:analysis*; D008872:Microwaves; D008958:Models, Molecular; D013057:Spectrum Analysis
chemical_list: D000097:Acetonitriles; D005609:Free Radicals; D006838:Hydrocarbons