J/A+A/609/A121 Lab measurements for C-cyanomethanimine (Melosso+, 2018)
Laboratory measurements and astronomical search for cyanomethanimine.
Melosso M., Melli A., Puzzarini C., Codella C., Spada L., Dore L.,
Degli Esposti C., Lefloch B., Bachiller R., Ceccarelli C., Cernicharo J.,
Barone V.
<Astron. Astrophys. 609, A121 (2018)>
=2018A&A...609A.121M 2018A&A...609A.121M (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics ; Interstellar medium
Keywords: ISM: molecules - molecular data - methods: data analysis -
methods: laboratory: molecular
Abstract:
C-cyanomethanimine (HNCHCN), existing in the two Z and E isomeric
forms, is a key prebiotic molecule, but, so far, only the E isomer has
been detected towards the massive star forming region Sagittarius
B2(N) using transitions in the radio wavelength domain.
With the aim of detecting HNCHCN in Sun-like star-forming regions, the
laboratory investigation of its rotational spectrum has been extended
to the milllimeter-/submillimeter-wave (mm-/submm-) spectral window
where several unbiased spectral surveys have been already obtained.
High-resolution laboratory measurements of the rotational spectrum of
C-cyanomethanimine were carried out in the 100-420GHz range using a
frequency-modulation absorption spectrometer. The C-cyanomethanimine
spectral features were then searched for in the mm-wave range using
the high-sensitivity and unbiased spectral surveys obtained with the
IRAM 30-m antenna in the ASAI context, the earliest stages of star
formation from starless to evolved Class I objects being sampled.
For both the Z and E isomers, the spectroscopic work has led to an
improved and extended knowledge of the spectroscopic parameters, thus
providing accurate predictions of the rotational signatures up to
∼700GHz. So far, no C-cyanomethanimine emission has been detected
towards the ASAI targets, and upper limits on the column density of
1011-1012cm-2 could only be derived. Consequently, the
C-cyanomethanimine abundances have to be less than a few 10-10 for
starless and hot-corinos. A less stringent constraint, ≤10-9, is
obtained for shocks sites. The combination of the upper limits on the
abundances of C-cyanomethanimine together with accurate laboratory
frequencies up to ∼700GHz poses the basis for future higher
sensitivity searches around Sun-like star forming regions. For compact
(typically less than 1 arcsec) and chemically enriched sources such as
hot-corinos, the use of interferometers as NOEMA and ALMA in their
extended configurations are clearly needed.
Description:
Table 2 contains measured rotational transitions and residuals from
the fit for the two isomers of C-cyanomethanimine in the ground state.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 80 1185 Measured rotational transitions and residuals
from the fit for the two isomers of
C-cyanomethanimine in the ground state
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See also:
J/A+A/562/A56 : Cyanomethyl anion & its deuterated derivatives (Majumdar+ 2014)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Species Isomer
8- 9 I2 --- N' Upper N quantum number
11- 12 I2 --- Ka' Upper Ka quantum number
14- 15 I2 --- Kc' Upper Kc quantum number
17- 18 I2 --- I' ? Upper I quantum number (1)
20- 21 I2 --- F' ? Upper F quantum number (1)
23- 24 I2 --- N Lower N quantum number
26- 27 I2 --- Ka Lower Ka quantum number
29- 30 I2 --- Kc Lower Kc quantum number
32- 33 I2 --- I ? Lower I quantum number (1)
35- 36 I2 --- F ? Lower F quantum number (1)
39- 49 F11.4 MHz Freq Observed frequency
53- 57 F5.3 MHz Unc Experimental uncertainty
61- 67 F7.4 MHz O-C Observed minus calculated frequencies
71- 74 F4.2 --- Weight ? Relative weight (2)
78- 80 A3 --- Ref Reference (3)
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Note (1): Omitted in cases of unresolved hyperfine components
Note (2): Given only for blended lines
Note (3): References as follows:
(a) = Zaleski et al. (2013ApJ...765L..10Z 2013ApJ...765L..10Z)
(b) = Takeo et al. (1986, CPL, 123, 229 )
(c) = Takano et al. (1990, J. Mol. Spectr., 141, 13)
(d) = This work
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Acknowledgements:
Mattia Melosso, mattia.melosso2(at)unibo.it
(End) Patricia Vannier [CDS] 17-Oct-2017