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Laboratory Measurements and Tentative Astronomical Identification of H_2NCO^+

Gupta, H. and Gottlieb, C. A. and Lattanzi, V. and Pearson, J. C. and McCarthy, M. C. (2013) Laboratory Measurements and Tentative Astronomical Identification of H_2NCO^+. Astrophysical Journal Letters, 778 (1). Art. No. L1. ISSN 2041-8205.

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The rotational spectrum of H_2NCO^+, 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_a ≤ 3 allow the principal rotational transitions to be calculated to 1 km s^(–1) or better in equivalent radial velocity well into the far IR. Two low-lying rotational transitions of H_2NCO^+ in the centimeter band (0_(0,0)-1_(0,1) and 1_(1,0)-2_(1,1)) were tentatively identified in absorption in the PRIMOS spectral line survey of Sgr B2(N) with the Green Bank Telescope. The lines of H_2NCO^+ arise in a region of the Sgr B2(N) halo whose density is low (n < 1 × 10^4 cm^(–3)). The derived column density of (6-14) × 10^(11) cm^(–2) implies that the fractional abundance is ~10^(–12). Owing to the ubiquity of HNCO in galactic molecular clouds, H_2NCO^+ is a good candidate for detection in sources spanning a wide range of physical conditions.

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McCarthy, M. C.0000-0002-5450-5894
Additional Information:© 2013 American Astronomical Society. Received 2013 July 30; accepted 2013 September 11; published 2013 October 30. We are indebted to P. F. Goldsmith, M. Gerin, and D. C. Lis for helpful discussions; S. Thorwirth for communicating results of his high-level coupled cluster quantum calculations; J. Neill for sharing unpublished measurements of HNCO in Sgr B2(N) with Herschel; and F. Crim for advice and D. Kokkin for assistance with the preparation of the HNCO precursor in the laboratory experiments. The work in Cambridge was supported by NASA Grants NNX13AE59G, NNX08AE05G, and NNX08AI41G. A portion of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
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Subject Keywords:ISM: molecules
Issue or Number:1
Record Number:CaltechAUTHORS:20140107-120245254
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Official Citation:Laboratory Measurements and Tentative Astronomical Identification of H2NCO+ H. Gupta et al. 2013 ApJ 778 L1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43247
Deposited By: Ruth Sustaita
Deposited On:07 Jan 2014 22:06
Last Modified:09 Mar 2020 13:19

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