title: The interstellar 4.62 micron band.
abstract: We present new 4.5-5.1 micron (2210-1970 cm-1) spectra of embedded protostars, W33 A, AFGL 961 E, AFGL 2136, NGC 7538 IRS 9, and Mon R2 IRS 2, which contain a broad absorption feature located near 4.62 micron (2165 cm-1), commonly referred to in the literature as the "X-C triple bond N" band. The observed peak positions and widths of the interstellar band agree to within 2.5 cm-1 and 5 cm-1, respectively. The strengths of the interstellar 4.62 micrometers band and the ice absorption features in these spectra are not correlated, which suggests a diversity of environmental conditions for the ices we are observing. We explore several possible carriers of the interstellar band and review possible production pathways through far-ultraviolet photolysis (FUV), ion bombardment of interstellar ice analog mixtures, and acid-base reactions. Good fits to the interstellar spectra are obtained with an organic residue produced through ion bombardment of nitrogen-containing ices or with the OCN- ion produced either through acid-base reactions or FUV photolysis of NH3-containing ices.
authors.affiliation: NASA Ames Research Center, Moffett Field, CA 94035, USA.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Pendleton
authors.forename: A G
authors.initials: AG
authors.lastname: Tielens
authors.forename: A T
authors.initials: AT
authors.lastname: Tokunaga
authors.forename: M P
authors.initials: MP
authors.lastname: Bernstein
mesh_terms: D000641:Ammonia / Q000032:analysis; D055580:Astronomical Phenomena; D001256:Astronomy; D019443:Cosmic Dust / Q000032:analysis*; D003485:Cyanates / Q000032:analysis; D005118:Extraterrestrial Environment; D006838:Hydrocarbons / Q000032:analysis; D007053:Ice / Q000032:analysis*; D009570:Nitriles / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D010782:Photolysis; D012821:Silanes / Q000032:analysis; D013055:Spectrophotometry, Infrared; D013057:Spectrum Analysis; D013861:Thiocyanates / Q000032:analysis; D014466:Ultraviolet Rays
chemical_list: D019443:Cosmic Dust; D003485:Cyanates; D006838:Hydrocarbons; D007053:Ice; D009570:Nitriles; D012821:Silanes; D013861:Thiocyanates; D000641:Ammonia; D009584:Nitrogen