Radio Observations of the Interstellar OH Line at 1,667 Mc/s

@article{Dieter1964RadioOO,
  title={Radio Observations of the Interstellar OH Line at 1,667 Mc/s},
  author={Nannielou H. Dieter and Harold I. Ewen},
  journal={Nature},
  year={1964},
  volume={201},
  pages={279-281}
}
THE first experimental evidence for the presence of 18-cm absorption lines of the hydroxyl (OH) radical in the radio absorption spectrum of Cassiopeia A, as suggested by Lilley1, was obtained by Weinreb et al.2 based on observations made during the period October 15–29, 1963. The Radio Physics Laboratory, Commonwealth Scientific and Industrial Research Organization, in Sydney, Australia, has reported the successful measurement of OH absorption in the spectrum of Sagittarius (see preceding… 
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Radio Observations of Interstellar Hydroxyl Radicals
TLDR
The discovery of the radio frequency lines of OH gave the first positive evidence of the existence of OH in the interstellar medium, but many observations have revealed totally unexpected anomalies in the radio-spectral properties of interstellar OH.
OH Absorption Spectra in Sagittarius
WE have measured the 18-cm OH absorption spectrum of Sagittarius A over a range of 6.4 Mc/s using the 60-ft. radio telescope of Harvard College Observatory. This frequency range covers both the 1,667…
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  • A. Barrett
  • Physics, Mathematics
    IEEE Transactions on Military Electronics
  • 1964
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WE would like to confirm Weinreb, Barrett, Meeks and Henry's1 discovery of the hydroxyl (OH) radical in the interstellar medium at frequency 1667.36 Mc/s. Fig. 1. shows observations of the…
High-resolution Microwave Spectra of H and OH Absorption Lines of Cassiopeia A
IN a recent communication Weinreb, Barrett, Meeks and Henry1 reported the discovery of the 18-cm lines of the hydroxyl (OH) radical in the radio absorption spectra of Cassiopeia A, and the result was…
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The available data on the microwave spectrum of the hydroxyl radical are critically reviewed for information applicable to radio astronomy. Molecular properties such as the rotational constants,…
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TLDR
The observed temporal changes in concentrations, especially the increase of HDO concentration during VUV irradiation, can be interpreted by a model with a rapid conversion from orthohydrogen (oH2) to pH2 in water-o H2 complexes upon VUV photodissociation.
Weak Interactions in Interstellar Chemistry: How Do Open Shell Molecules Interact with Closed Shell Molecules?
The interstellar medium (ISM) is home to several open shell and closed shell molecules considered to be unusual or highly unstable on Earth. The chemistry of these molecules in the ISM has been…
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References

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Radio Observations of OH in the Interstellar Medium
Existence of oh in interstellar medium, detected in radio absorption spectrum of cassiopeia-a
Observation of a Line in the Galactic Radio Spectrum: Radiation from Galactic Hydrogen at 1,420 Mc./sec.
A Note on the Galactic Microwave Spectrum.