Laboratory characterization and astrophysical detection in Orion KL of higher excited states of

vinyl cyanide

Alicia Lopez,a Belen Tercero,a Jose Cernicharo,a Zbigniew Kisiel,b Lech Pszczółkowski,b Celina Bermudez,c Jose L.Alonso,c Ivan R.Medvedev,d Christopher Neesee, Brian J.Drouin,f

Adam M.Daly,f Nuria Marcelino,g Serena Viti,h Hannah Calcutt,h

aDepartamento de Astrofısica, Centro de Astrobiologia CAB, CSIC-INTA, Madrid, Spain bInstitute of Physics, Polish Academy of Sciences, Warszawa, Poland

cGrupo de Espectroscopia Molecular, Universidad de Valladolid, Valladolid, SpaindDepartment of Physics, Wright State University, Dayton, OH 45435, USA

eDepartment of Physics, The Ohio State University, Columbus, OH 43210, USAfJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

gALMA, National Radio Astronomy Observatory, Charlottesville, VA, USAhDepartment of Physics and Astronomy, University College London, UK

69th International Symposium on Molecular Spectroscopy WF1169th International Symposium on Molecular Spectroscopy WF11

Rotational spectroscopy of acrylonitrile:

Recent laboratory papers: revised: Krasnicki+Kisiel, , J.Mol.Spectrosc. 270, 83 (2011) isotopic+struct: Krasnicki et al., J.Mol.Struct. 1006, 20 (2011) gs to 211: Kisiel et al., J.Mol.Spectrosc. 280, 134 (2012)

Planar (Cs), relatively rigid molecule,positioned in the ab inertial plane

a = 3.821(3) Db = 0.687(8) D

Class 2 astrophysical weed as of 2006 !

Some relevant astrophysical papers:first astro, Sgr B2: Gardner+Winnewisser, Astrophys.J. . 195, L127 (1975)isot. in Sgr B2: Muller et al., J.Mol.Spectrosc. 251, 319 (2008) isot.+es. Sgr B2: Belloche at al., A&A 559, A47 1-187 (2013)

The acrylonitrile rotational spectrum:

a type transitions

b type transitions

updated spectra used in this work

The recorded spectra:

Multiplier of cmw-region pump frequency in cascaded multiplication

GHz

Analysis: AABS package + Pickett’s SPFIT/SPCAT

Spectrum handling: single spectrum (37Mpoints @ 0.05 MHz) + modified baseline subtraction

Loomis-Wood displays: assignment

Difference-frequency plots: location of pairwise perturbations

Distribution plots: essential book-keeping for large data sets

AABS = Assignment and Analysis of Broadband Spectra, available at: http://info.ifpan.edu.pl/~kisiel/prospe.htm

Our previous work on the THz-level spectrum of acrylonitrile:

J.Mol.Spectrosc. 2009:

g.s. n11 perturbations

J.Mol.Struct. 2011:

g.s. n11 perturbations in isotopic acrylonitrile

J.Mol.Spectrosc. 2012:

g.s. n11 n15 2n11 fit

TH10, OSU symposium 2012:

n10 n11n15 fit

Vibrational levels of vinyl cyanide up to 1000 cm-1

All states marked in red have been studied in this work

Rectangles identify polyads of vibrational states treated in terms of coupled fits

The Stark-modulation spectrum of the 413 ← 312 transition:

Each marked line corresponds to the 413 ← 312 transition in either an excited state of the parent species or an isotopic ground state

- note the characteristic lineshape

Analysed in the current work

States in a coupled fit detected in Orion-KL

Summary of fits:

Consistent set of vibrational energies derived by taking advantage of the results of the perturbation analyses and calculated anharmonicity coefficients

Made with a block diagonal Hamiltonian as required by the Cs symmetry of vinyl cyanide with either a-type+b-type Coriolis or c-type Coriolis+Fermi off-diagonal blocks

(details: Kisiel et al., , J.Mol.Spectrosc. 280, 134 (2012))

Perturbations in lowest Ka, aR-type transitions

Perturbation magnitude:

2700 MHz (45x60)

Perturbations are within blocks for a given value of J

Mirror image difference frequency plots relative to the ground state for two vibrational states identify perturbing Ka sequences.

Take-home message: in cases like these it is mandatory to account for perturbations, otherwise linelists will not correctly predict key transitions that may be searched for

Ka+Kc=J +1

Ka+Kc= J

Spectroscopic constants:

a-axis Coriolis

b-axis Coriolis

Confirmation of vibrational assignment by (Bv-B0) values:

different anharmonic force

field calculations

using summation of single excitation vibrational changes

ABC

Observed 11=1 lines (228 cm-1) in Orion KL:

Vinyl cyanide

Complete model (MADEX)IRAM-30m, 9 adjacent panels out of a much larger selection

Observed 11=2 lines (457 cm-1) in Orion KL:

Vinyl cyanide Complete model

Observed n10 n11,n15 dyad (560 cm-1) lines in Orion KL:

Vinyl cyanide Complete model

Vinyl cyanide Complete model

Observed 13C vinyl cyanide lines in Orion KL:

The coverage of the room temperature rotational spectrum of acrylonitrile has been increased in extent to a total of 1248 GHz corresponding to 65.7% of the range up to the upper frequency limit to 1.9 THz

Continuous coverage of the 50-640 GHz region

Broadband coverage turned out to be crucial to locating specific pairwise perturbations between vibrational states

Coupled fits of: n10 n11,n15 dyad (3972 lines)2n15 n14 3n11 triad (3866 lines)n10 n11 2n11,n15 dyad (1702 lines)

Laboratory data and linelists at http://info.ifpan.edu.pl/~kisiel/data.htm

Astrophysical part of this investigation reports a massive amount of data on Orion-KL: column densities, abundances, rotational plots, intensity maps, other molecules (including vinyl isocyanide), soon in A&A?

SUMMARY: