title: Upper limits for the ethyl-cyanide abundances in TMC-1 and L134N:  chemical implications.
abstract: We have sought interstellar ethyl-cyanide via its 2(02)-1(01) transition towards two cold, dark clouds and  report upper limits of the total column densities of 3 x 10(12) cm-2 and 2 x 10(12) cm-2 for TMC-1 and L134N, respectively.  We also observed the 2(02)-1(01) transition of vinyl cyanide previously identified in TMC-1 by Matthews and Sears (1983b).  The detection of vinyl cyanide and the non-detection of ethyl cyanide in TMC-1 are consistent with gas phase ion-molecule chemical models, and there is thus no necessity of invoking grain surface synthesis for vinyl cyanide in cold clouds.
authors.affiliation: Department of Physics and Astronomy, University of Massachusetts, Amherst, USA.
authors.forename: Y C
authors.initials: YC
authors.lastname: Minh
authors.forename: W M
authors.initials: WM
authors.lastname: Irvine
mesh_terms: D000181:Acrylonitrile / Q000032:analysis* / Q000737:chemistry; D055580:Astronomical Phenomena; D001256:Astronomy; D005118:Extraterrestrial Environment; D008956:Models, Chemical; D009570:Nitriles / Q000032:analysis* / Q000737:chemistry; D016082:Solar System
chemical_list: D009570:Nitriles; C005557:propionitrile; D000181:Acrylonitrile