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Title: THE MICROWAVE SPECTROSCOPY OF METHYL FORMATE IN THE SECOND TORSIONAL EXCITED STATE

Abstract

The cis-methyl formate molecule is a well known molecule found in interstellar space. Recently, rotational lines of methyl formate in the first CH{sub 3} torsional excited state were observed in Orion KL and W51e2. It is quite natural to observe methyl formate in even higher vibrational states considering the temperature estimated in Orion KL and W51e2. Maeda et al. reported results on the laboratory spectroscopy of methyl formate including the spectral analysis in its second CH{sub 3} torsional state. Their assignments were limited to a series of a-type R-branch lines and low K{sub a} b-type R-branch transitions, and many assigned lines are excluded in the least-squares analysis. In the present study, we extended the line assignments of both the A- and E-species transitions in the second CH{sub 3} torsional state especially in the frequency region below the 120 GHz region. By combining the present assignments and those made by Maeda et al., 1951 transitions in total for the second CH{sub 3} torsional state, 1096 A-species transitions up to J = 39, and K{sub a} = 15 and 855 E-species transitions up to J = 35 and K{sub a} = 13, were least-squares analyzed by using the pseudo-principal-axis-method Hamiltonian with 42more » parameters consisting of rotational, centrifugal distortion, and internal rotational constants in the second CH{sub 3} torsional state. In addition, 1012 transitions out of 1096 A-species transitions could also be least-squares analyzed by using Watson's A-reduced Hamiltonian with 43 parameters, which can serve to calculate the energy levels of the A-species lines of molecules with the CH{sub 3} internal rotation conveniently.« less

Authors:
; ; ;  [1];  [2];  [3]
  1. Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan)
  2. Department of Physics, Meiji University, 1-1-1 Higashi-mita, Tama-ku, Kawasaki 214-8571 (Japan)
  3. Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)
Publication Date:
OSTI Identifier:
22156571
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal, Supplement Series
Additional Journal Information:
Journal Volume: 205; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0067-0049
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; FORMATES; GHZ RANGE 100-1000; HAMILTONIANS; INTERSTELLAR SPACE; LEAST SQUARE FIT; MICROWAVE RADIATION; MOLECULES; SPECTROSCOPY; VIBRATIONAL STATES

Citation Formats

Kobayashi, Kaori, Takamura, Kazunori, Sakai, Yusuke, Tsunekawa, Shozo, Odashima, Hitoshi, and Ohashi, Nobukimi. THE MICROWAVE SPECTROSCOPY OF METHYL FORMATE IN THE SECOND TORSIONAL EXCITED STATE. United States: N. p., 2013. Web. doi:10.1088/0067-0049/205/1/9.
Kobayashi, Kaori, Takamura, Kazunori, Sakai, Yusuke, Tsunekawa, Shozo, Odashima, Hitoshi, & Ohashi, Nobukimi. THE MICROWAVE SPECTROSCOPY OF METHYL FORMATE IN THE SECOND TORSIONAL EXCITED STATE. United States. doi:10.1088/0067-0049/205/1/9.
Kobayashi, Kaori, Takamura, Kazunori, Sakai, Yusuke, Tsunekawa, Shozo, Odashima, Hitoshi, and Ohashi, Nobukimi. Fri . "THE MICROWAVE SPECTROSCOPY OF METHYL FORMATE IN THE SECOND TORSIONAL EXCITED STATE". United States. doi:10.1088/0067-0049/205/1/9.
@article{osti_22156571,
title = {THE MICROWAVE SPECTROSCOPY OF METHYL FORMATE IN THE SECOND TORSIONAL EXCITED STATE},
author = {Kobayashi, Kaori and Takamura, Kazunori and Sakai, Yusuke and Tsunekawa, Shozo and Odashima, Hitoshi and Ohashi, Nobukimi},
abstractNote = {The cis-methyl formate molecule is a well known molecule found in interstellar space. Recently, rotational lines of methyl formate in the first CH{sub 3} torsional excited state were observed in Orion KL and W51e2. It is quite natural to observe methyl formate in even higher vibrational states considering the temperature estimated in Orion KL and W51e2. Maeda et al. reported results on the laboratory spectroscopy of methyl formate including the spectral analysis in its second CH{sub 3} torsional state. Their assignments were limited to a series of a-type R-branch lines and low K{sub a} b-type R-branch transitions, and many assigned lines are excluded in the least-squares analysis. In the present study, we extended the line assignments of both the A- and E-species transitions in the second CH{sub 3} torsional state especially in the frequency region below the 120 GHz region. By combining the present assignments and those made by Maeda et al., 1951 transitions in total for the second CH{sub 3} torsional state, 1096 A-species transitions up to J = 39, and K{sub a} = 15 and 855 E-species transitions up to J = 35 and K{sub a} = 13, were least-squares analyzed by using the pseudo-principal-axis-method Hamiltonian with 42 parameters consisting of rotational, centrifugal distortion, and internal rotational constants in the second CH{sub 3} torsional state. In addition, 1012 transitions out of 1096 A-species transitions could also be least-squares analyzed by using Watson's A-reduced Hamiltonian with 43 parameters, which can serve to calculate the energy levels of the A-species lines of molecules with the CH{sub 3} internal rotation conveniently.},
doi = {10.1088/0067-0049/205/1/9},
journal = {Astrophysical Journal, Supplement Series},
issn = {0067-0049},
number = 1,
volume = 205,
place = {United States},
year = {2013},
month = {3}
}