Microwave and submillimeter spectroscopy and first ISM detection of 18O-methyl formate
Abstract
Context. Astronomical survey of interstellar molecular clouds needs a previous analysis of the spectra in the microwave and sub-mm energy range to be able to identify them. We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of rotational spectra. These constants can be used to predict transition frequencies that were not measured in the laboratory very precisely.
Aims: We present an experimental study and a theoretical analysis of two 18O-methyl formate isotopologues, which were subsequently detected for the first time in Orion KL.
Methods: The experimental spectra of both methyl formate isotopologues recorded in the microwave and sub-mm range from 1 to 660 GHz. Both spectra were analysed by using the rho-axis method (RAM) which takes into account the CH3 internal rotation.
Results: We obtained spectroscopic constants of both 18O- methyl formate with high accuracy. Thousands of transitions were assigned and others predicted, which allowed us to detect both species in the IRAM 30 m line survey of Orion KL.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- February 2012
- DOI:
- 10.1051/0004-6361/201117072
- Bibcode:
- 2012A&A...538A.119T
- Keywords:
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- astrochemistry;
- ISM: molecules;
- submillimeter: ISM;
- line: identification;
- astronomical databases: miscellaneous;
- ISM: individual objects: Orion KL