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Title: LABORATORY MEASUREMENTS AND TENTATIVE ASTRONOMICAL IDENTIFICATION OF H{sub 2}NCO{sup +}

The rotational spectrum of H{sub 2}NCO{sup +}, the ground-state isomer of protonated HNCO, has been measured in a molecular beam in the centimeter band with a Fourier transform microwave spectrometer and in a low-pressure laboratory discharge in absorption in the millimeter band. Spectroscopic constants, including the nitrogen-14 hyperfine coupling constant, derived from 30 a-type transitions between 20 and 367 GHz with J ≤ 18 and K{sub a} ≤ 3 allow the principal rotational transitions to be calculated to 1 km s{sup –1} or better in equivalent radial velocity well into the far IR. Two low-lying rotational transitions of H{sub 2}NCO{sup +} in the centimeter band (0{sub 0,} {sub 0}-1{sub 0,} {sub 1} and 1{sub 1,} {sub 0}-2{sub 1,} {sub 1}) were tentatively identified in absorption in the PRIMOS spectral line survey of Sgr B2(N) with the Green Bank Telescope. The lines of H{sub 2}NCO{sup +} arise in a region of the Sgr B2(N) halo whose density is low (n < 1 × 10{sup 4} cm{sup –3}). The derived column density of (6-14) × 10{sup 11} cm{sup –2} implies that the fractional abundance is ∼10{sup –12}. Owing to the ubiquity of HNCO in galactic molecular clouds, H{sub 2}NCO{sup +} is a good candidatemore » for detection in sources spanning a wide range of physical conditions.« less
Authors:
;  [1] ; ; ;  [2]
  1. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22364141
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 778; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTRA; ABUNDANCE; ASTROPHYSICS; COUPLING CONSTANTS; ELECTRIC DISCHARGES; FOURIER TRANSFORMATION; GHZ RANGE; GROUND STATES; ISOMERS; MICROWAVE RADIATION; MILKY WAY; MOLECULAR BEAMS; MOLECULES; NITROGEN 14; RADIAL VELOCITY; STARS; TELESCOPES