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Submillimeter-Wave Measurements and Analysis of the Ground and ν2 = 1 States of Water

Chen, Pin and Pearson, J. C. and Pickett, Herbert M. and Matsuura, Shuji and Blake, Geoffrey A. (2000) Submillimeter-Wave Measurements and Analysis of the Ground and ν2 = 1 States of Water. Astrophysical Journal Supplement Series, 128 (1). pp. 371-385. ISSN 0067-0049. doi:10.1086/313377.

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In order to facilitate further studies of water in the interstellar medium, the envelopes of late-type stars, jets, and shocked regions, the frequencies of 17 newly measured H_2 ^(16)O transitions between 0.841 and 1.575 THz are reported. A complete update of the available water line frequencies and a detailed calculation of unmeasured rotational transitions and transition intensities as a function of temperature are presented for the ground and ν_2 = 1 state levels below 3000 cm^(-1) of excitation energy. The new terahertz transitions were measured with a recently developed laser difference frequency spectrometer. Six of these transitions arise from the ν_2 = 1 state, and the other 11 are in the ground state; all have lower state energies from 700 to 1750 cm^(-1) and should be accessible to Stratospheric Observatory For Infrared Astronomy (SOFIA) through the atmosphere. The transitions near 0.850 THz are accessible from the ground with existing receivers. Observations of the newly measured ν_2 = 1 state transitions, which include the 1_(1, 1)-0_(0, 0) fundamental at 1.2057 THz and five other very low J transitions, should provide valuable insights into role played by the ν2 = 1 state in the cooling dynamics of jets, shocks, masers, and strongly infrared-pumped regions. The line list is presented to assist in the planning of observational campaigns with the Far-Infrared Space Telescope (FIRST) and other proposed space missions with which a full suite of water observations can be carried out.

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Matsuura, Shuji0000-0002-5698-9634
Blake, Geoffrey A.0000-0003-0787-1610
Additional Information:© 2000 American Astronomical Society. Received 1999 July 15; accepted 1999 November 24. Parts of the research described in this paper were carried out by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). G. A. Blake acknowledges the support of NASA and the National Science Foundation. We thank Simon Verghese of MIT Lincoln Laboratories for supplying the photomixers used in this study. J. C. Pearson thanks Robert A. Toth for making available his latest water measurements prior to publication and for useful discussions concerning their analysis.
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Subject Keywords:infrared: ISM; ISM: lines and bands; ISM: molecules; methods: laboratory; molecular data
Issue or Number:1
Record Number:CaltechAUTHORS:20120914-103111591
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Official Citation:Submillimeter-Wave Measurements and Analysis of the Ground and ν2 = 1 States of Water Pin Chen et al. 2000 ApJS 128 371
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:34092
Deposited On:14 Sep 2012 18:33
Last Modified:09 Nov 2021 23:06

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