J/ApJS/184/133 New ground-state measurements of ethyl cyanide (Brauer+, 2009)
New ground-state measurements of ethyl cyanide.
Brauer C.S., Pearson J.C., Drouin B.J., Yu S.
<Astrophys. J. Suppl. Ser., 184, 133-137 (2009)>
=2009ApJS..184..133B 2009ApJS..184..133B
ADC_Keywords: Atomic physics ; Spectroscopy
Keywords: catalogs - line: identification - methods: laboratory - molecular data
techniques: spectroscopic
Abstract:
The spectrum of ethyl cyanide, or propionitrile (CH3CH2CN), has been
repeatedly observed in the interstellar medium with large column
densities and surprisingly high temperatures in hot core sources. The
construction of new, more sensitive, observatories accessing higher
frequencies such as Herschel, ALMA, and SOFIA have made it important
to extend the laboratory data for ethyl cyanide to coincide with the
capabilities of the new instruments. We report extensions of the
laboratory measurements of the rotational spectrum of ethyl cyanide in
its ground vibrational state to 1.6THz. A global analysis of the
ground state, which includes all of the previous data and 3356 newly
assigned transitions, has been fitted to within experimental error
to J=132, K=36, using both Watson A-reduced and Watson S-reduced
Hamiltonians.
Description:
Several large, nearly complete portions of the spectrum between 595
and 1626GHz were recorded using a commercial synthesizer, driving
actively multiplied sources at JPL (Jet Propulsion Laboratory).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
a200k.dat 73 46920 A-reduced, T=200K predictions
a300k.dat 73 64344 A-reduced, T=300K predictions
a500k.dat 73 88833 A-reduced, T=500K predictions
s200k.dat 73 46973 S-reduced, T=200K predictions
s300k.dat 73 64523 S-reduced, T=300K predictions
s500k.dat 73 89182 S-reduced, T=500K predictions
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See also:
http://spec.jpl.nasa.gov : JPL catalog home page
http://www.astro.uni-koeln.de/cdms/catalog : the Cologne Database for
Molecular Spectroscopy
J/A+A/466/255 : Isotopic ethyl cyanide (Demyk+, 2007)
J/ApJS/181/433 : Spectrum of ethyl formate (Medvedev+, 2009)
Byte-by-byte Description of file (#): [as]*.dat
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Bytes Format Units Label Explanations
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2- 13 F12.4 MHz Freq Frequency of the line
14- 21 F8.4 MHz e_Freq Estimated or experimental error of Freq
23- 29 F7.4 [nm+2.MHz] lgInt Base 10 logarithm of the integrated intensity
in units of nm2MHz at 300K (1)
31 I1 --- DOF [3] Degrees of freedom in the rotational
partition function (0 for atoms, 2 for linear
molecules, and 3 for nonlinear molecules) (1)
33- 41 F9.4 cm-1 E0 Lower state energy relative to the ground state
42- 44 I3 --- g Upper state degeneracy
47- 51 I5 --- Tag [55001] Species tag or molecular identifier (1)
53- 55 I3 --- QNFMT [303] Identifies the format of the quantum
numbers (1)
56- 57 A2 --- J' Upper J quantum number (2)
58- 59 I2 --- Ka' Upper Ka quantum number (2)
60- 61 A2 --- Kc' Upper Kc quantum number (2)
68- 69 A2 --- J" Lower J quantum number (2)
70- 71 I2 --- Ka" Lower Ka quantum number (2)
72- 73 A2 --- Kc" Lower Kc quantum number (2)
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Note (1): More explanations about these parameters can be found in the
paper by Muller et al. 2001A&A...370L..49M 2001A&A...370L..49M
A negative value of Tag indicates that the line frequency has been
measured in the laboratory. The absolute value of Tag is then the
species tag and e_Freq is the reported experimental error. The three
most significant digits of the species tag are coded as the mass
number of the species.
Note (2): The rotational levels of an asymmetric top are characterized by
the overall rotational quantum number J and two pseudo-quantum numbers
Ka and Kc, which represent the projections of the total angular
momentum on the symmetry axes of the prolate and oblate symmetric
top limits (Gordy & Cook, 1984, Microwave Molecular Spectra
(New York: Wiley)).
Quanta numbers are coded with uppercase letters for values larger than
100 (e.g. values between 100 and 109 are shown as A0 through A9, and
Z9 stands for 359). Negative quanta numbers below -10 are coded with
lowercase letters (e.g. values between -10 and -19 are shown as a0
through a9, and z9 stands for -259).
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 12-Feb-2010