J/A+A/564/A82 Microwave spectra of CH3CHCCHCN (Carles+, 2014)
Rotational spectrum of 4-methylcyanoallene (CH3CH=C=CH-CN), a chiral molecule
of potential astrochemical interest.
Carles S., Mollendal H., Trolez Y., Guillemin J.-C.
<Astron. Astrophys. 564, A82 (2014)>
=2014A&A...564A..82C 2014A&A...564A..82C
ADC_Keywords: Atomic physics
Keywords: methods: data analysis - surveys - molecular data -
methods: analytical - techniques: spectroscopic
Abstract:
A successful identification of an interstellar compound requires that
its spectrum has first been assigned in the laboratory. New and
sensitive radiotelescopes, such as ALMA, will make it possible to
detect interstellar molecules in much smaller concentrations than
before. Cyanoallene (CH2=C=CH-CN) has recently been observed in the
dense molecular cloud TMC-1 by means of its rotational spectrum. Its
methyl congener, 4-methylcyanoallene (CH3CH=C=CH-CN), may also be
present in the interstellar medium (ISM). This chiral compound exists
in two forms, which are mirror images. Chirality is an essential
feature of life. So far, no chiral compounds have been detected in the
ISM.
The synthesis and assignment of the rotational spectrum of
CH3CH=C=CH-CN, will facilitate the potential detection of this
compound in the ISM.
Description:
The CH3CH=C=CH-CN molecule is a candidate for a possible interstellar
detection. We have recorded the microwave spectra of this molecule
between 13 and 116GHz. We have assigned 654 transitions of the ground
state (Table 3) and 379 transitions of the first excited state of the
lowest bending vibration (Table 4). Sorensen' s program ROTFIT was
used to least-squares fit the lines employing Watson' s S-reduction
and Ir-representation.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 76 654 Rotational spectrum of CH3CH=C=CH-CN in the
ground vibrational state
table4.dat 74 379 Rotational spectrum of CH3CH=C=CH-CN in the
lowest vibrationally excited state
--------------------------------------------------------------------------------
See also:
J/A+A/466/255 : Isotopic ethyl cyanide (Demyk+, 2007)
J/A+A/493/565 : Deuterated and 15N ethyl cyanides (Margules+, 2009)
J/ApJ/714/476 : Complete spectrum of ethyl cyanide (Fortman+, 2010)
J/ApJS/184/133 : New ground-state measurements of ethyl cyanide (Brauer+, 2009)
J/A+A/543/A135 : New analysis of 13C-CH3CH2CN up to 1THz (Richard+, 2012)
J/A+A/558/A6 : Microwave spectra EtCCCN (C2H5CCCN) (Carles+, 2013)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ju [5/52] Transition J of the upper level (1)
4- 5 I2 --- K-1u [0/30] Transition K-1 of the upper level
7- 8 I2 --- K+1u [3/50] Transition K+1 of the upper level
10- 11 I2 --- Jl [6/52] Transition J of the lower level
13- 14 I2 --- K-1l [0/30] Transition K-1 of the lower level
16- 17 I2 --- K+1l [4/49] Transition K+1 of the lower level
19- 28 F10.3 MHz Freq [18124/114662] Observed frequency
30- 35 F6.3 MHz O-C [-0.6/0.5] Observed minus Calculated residual
37- 40 F4.2 MHz e_Freq [-0.6/0.5] Estimated uncertainties of the
observed frequencies (G1)
42- 45 F4.1 --- t [-2/2] Student's t-test
47- 54 F8.3 MHz CorrT [-328/1310] Total Distortion Corrections:
correction from quartic and sextic (if included)
centrifugal distortion constants
56- 63 E8.2 MHz CorrH [-68/1.4] Higher Distortion Corrections:
contribution from sextic centrifugal distortion
constants
65- 76 E12.6 MHz Eu [64328/11883000] Upper energy
--------------------------------------------------------------------------------
Note (1):
rms deviation: 1.3595
Rotational constants (MHz) and kappa:
12732.907 1576.05831 1488.96638 -0.98450865
± 0.015 0.00083 0.00081 0.00000008
Inertial constants and defect (uÅ**2):
39.690786 320.660139 339.416043 -20.93488
± 0.000047 0.00017 0.00018 0.00010
Quartic distortion constants:
0.586265 -22.93721 327.05 -0.1050828 -0.0033843
± 0.0010 0.0033 0.85 0.000096 0.000032
Standard distortion constants (kHz):
-1218.811 -3.212795 -1.531471 43.94969 -2.263835 43.10903
Sextic and higher distortion constants:
0.002362 -0.037678 -1.0664 0 0
± 0.00040 0.0016 0.0026 fixed fixed
± fixed fixed
0 0
Significant Digits and Correlation Matrix:
-------------------------------------------------------------------------
8 0.031 0.078
9 0.868
9
0.020 0.074 0.898 0.047 -0.089 0.018 0.029 0.046
0.860 0.019 -0.014 -0.293 0.196 0.732 0.065 -0.090
0.847 0.036 0.027 0.179 -0.112 0.719 0.066 -0.068
6 -0.363 0.015 -0.090 0.082 0.963 -0.257 -0.080
7 -0.021 0.057 -0.080 -0.517 0.867 -0.075
5 0.022 -0.042 0.024 -0.020 -0.010
7 -0.803 -0.089 0.027 0.032
5 0.092 -0.073 0.017
4 -0.457 0.043
5 -0.543
5
-------------------------------------------------------------------------
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ju [5/36] J of the upper level (1)
4- 5 I2 --- K-1u [0/15] K-1 of the upper level
7- 8 I2 --- K+1u [4/35] K+1 of the upper level
10- 11 I2 --- Jl [6/37] J of the lower level
13- 14 I2 --- K-1l [0/15] K-1 of the lower level
16- 17 I2 --- K+1l [5/36] K+1 of the lower level
19- 27 F9.2 MHz Freq [18170/114618] Observed frequency
29- 34 F6.3 MHz O-C [-0.6/0.7] Observed minus Calculated residuals
36- 39 F4.2 MHz e_Freq [0.1/0.25] Estimated uncertainties of the
observed frequencies (G1)
41- 44 F4.1 --- t [-2/2.6] Student's t-test
46- 53 F8.3 MHz CorrT [-130/240] Total Distortion Corrections:
correction from quartic and sextic (if included)
centrifugal distortion constants
55- 64 E10.4 MHz CorrH [-2.7/0.95] Higher Distortion Corrections:
contribution from sextic centrifugal distortion
constants
66- 74 E9.3 MHz CorrF [-0.5/0.95] Fixed Distortion Corrections:
contribution from fixed quartic and/or
fixed sextic centrifugal distortion constants
--------------------------------------------------------------------------------
Note (1):
rms deviation: 1.4316
Rotational constants (MHz) and kappa:
12765.402 1581.9800 1492.0504 -0.9840456
± 0.055 0.0014 0.0013 0.0000004
Inertial constants and defect (uÅ**2):
39.589751 319.45984 338.71448 -20.3351
± 0.00017 0.00028 0.00029 0.0006
Quartic distortion constants:
0.596914 -22.7018 338.2 -0.105874 -0.003614
± 0.00037 0.012 4.7 0.00059 0.00037
Standard distortion constants (kHz):
-1264.504 -3.263561 -1.569574 43.43938 -2.300924 42.59238
Sextic and higher distortion constants:
0.002362 -0.037678 -0.6914 0 0
± fixed fixed 0.069 fixed fixed
± fixed fixed
0 0
Significant Digits and Correlation Matrix:
-----------------------------------------------------------------------
8
0.497 -0.371 -0.009 0.158 0.942 -0.193 -0.625 0.121
8 -0.523 0.286 0.258 0.358 -0.621 -0.227 0.187
8 0.448 0.064 -0.272 0.727 0.109 0.063
6 -0.158 -0.015 0.213 -0.037 -0.107
6 0.083 -0.081 -0.061 0.954
4 -0.116 -0.590 0.053
6 -0.076 -0.044
4 -0.033
4
-----------------------------------------------------------------------
--------------------------------------------------------------------------------
Global notes:
Note (G1): Each transition is weighted according to the inverse square of its
estimated uncertainty.
--------------------------------------------------------------------------------
Acknowledgements:
Sophie Carles, sophie.carles(at)univ-rennes1.fr
(End) Sophie Carles [IPR, France], Patricia Vannier [CDS] 05-Feb-2014