title: Identification of the interstellar cyanomethyl radical (CH2CN) in the molecular clouds TMC-1 and Sagittarius B2.
abstract: We report the astronomical identification of the cyanomethyl radical, CH2CN, the heaviest nonlinear molecular radical to be identified in interstellar clouds.  The complex fine and hyperfine structures of the lowest rotational transitions at about 20.12 and 40.24 GHz are resolved in TMC-1, where the abundance appears to be about 5 x 10(-9) relative to that of H2.  This is significantly greater than the observed abundance of CH3CN (methyl cyanide) in TMC-1.  In Sgr B2 the hyperfine structure is blended in the higher frequency transitions at 40, 80, and 100 GHz, although the spin-rotation doubling is clearly evident.  Preliminary searches in other sources indicate that the distribution of CH2CN is similar to that for such carbon chain species as HC3N or C4H.
authors.affiliation: Five College Radio Astronomy Observatory, University of Massachusetts, USA.
authors.forename: W M
authors.initials: WM
authors.lastname: Irvine
authors.forename: P
authors.initials: P
authors.lastname: Friberg
authors.forename: A
authors.initials: A
authors.lastname: Hjalmarson
authors.forename: S
authors.initials: S
authors.lastname: Ishikawa
authors.forename: N
authors.initials: N
authors.lastname: Kaifu
authors.forename: K
authors.initials: K
authors.lastname: Kawaguchi
authors.forename: S C
authors.initials: SC
authors.lastname: Madden
authors.forename: H E
authors.initials: HE
authors.lastname: Matthews
authors.forename: M
authors.initials: M
authors.lastname: Ohishi
authors.forename: S
authors.initials: S
authors.lastname: Saito
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: P
authors.initials: P
authors.lastname: Thaddeus
authors.forename: B E
authors.initials: BE
authors.lastname: Turner
authors.forename: S
authors.initials: S
authors.lastname: Yamamoto
authors.forename: L M
authors.initials: LM
authors.lastname: Ziurys
mesh_terms: D000097:Acetonitriles / Q000032:analysis* / Q000737:chemistry; D055580:Astronomical Phenomena; D001256:Astronomy; D055598:Chemical Phenomena; D002621:Chemistry; D005118:Extraterrestrial Environment; D005609:Free Radicals / Q000032:analysis* / Q000737:chemistry; D006838:Hydrocarbons / Q000032:analysis*; D013057:Spectrum Analysis
chemical_list: D000097:Acetonitriles; D005609:Free Radicals; D006838:Hydrocarbons