Laboratory millimeter wave spectrum and astronomical search for vinyl acetate

Abstract

Context. The recent discovery of methyl acetate in Orion KL makes vinyl acetate, CH 3 C=OOCH=CH 2 , a potential molecule in the interstellar medium. We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of its rotational spectra which can be used to predict those transition frequencies towards interstellar sources. Aims. We present the experimental study and theoretical analysis of the ground torsional state of vinyl acetate in a large spectral range for astrophysical use. Methods. The room-temperature rotational spectrum of vinyl acetate has been measured from 125 to 305 GHz to provide direct frequencies to the astronomical community. Additional measurements have also been made using a broadband CP-FTMW spectrometer in the region of 6−18 GHz. Transition lines, corresponding to the most stable conformer, have been observed and assigned. All the rotational transitions revealed the A-E splitting due to the methyl internal rotation and had to be treated with a specific internal rotation code (BELGI-Cs). Results. We analyzed 2508 transitions up to J = 75 for v t = 0 for the most stable conformer of vinyl acetate. The new lines were globally fitted with previously published data and 24 parameters of the Hamiltonian were accurately determined. The spectral features of vinyl acetate were then searched for in Orion KL. Using the whole line survey of Orion KL (80−280 GHz) obtained with the IRAM 30 m radio telescope we can provide only an upper limit to the column density of vinyl acetate. However, using the ALMA science verification data we obtain a tentative detection of this species that will require further search at other frequencies to confirm its presence in this high mass star forming region.

Rotational spectroscopic study of S-methyl thioformate

“…For calculations of the line strengths, we used the same procedure as the one described in detail in Section 3.2 of (Kleiner 2010). This method had been used for different molecules with C s symmetry containing one methyl rotor such as methyl formate and its isotopologues (Favre et al 2014;Carvajal et al 2009;Haykal et al 2014;Carvajal et al 2007;Tercero et al 2012;Duan et al 2015) or vinyl acetate (Kolesnikova et al 2015). We used the BELGI-C s code to calculate the line strengths, using the energy parameters determined in Table 2.…”

Rotational Fingerprints of Vinylketene for Astronomical Observations

“…This is demonstrated by first detections of vinylacetylene (C 2 H 3 CCH; Cernicharo et al 2021a), vinylcyanoacetylene (C 2 H 3 C 3 N; Lee et al 2021), and vinylamine (C 2 H 3 NH 2 ; Zeng et al 2021) as well as by observations of excited vibrational states (see, e.g., Belloche et al 2013;López et al 2014) and isotopic species (Müller et al 2008) for vinylcyanide (C 2 H 3 CN): the first vinyl-bearing molecule found in the ISM (Gardner & Winnewisser 1975). Interstellar searches were reported for vinyl formate (C 2 H 3 OCHO; Alonso et al 2016;Coutens et al 2022), vinyl acetate (C 2 H 3 OC(O)CH 3 ; Kolesniková et al 2015), vinyl mercaptan (C 2 H 3 SH; Martin-Drumel et al 2019), vinylisocyanate (C 2 H 3 NCO; Rodríguez-Almeida et al 2021;Vávra et al 2022), acrylic acid (C 2 H 3 C(O)OH; Alonso et al 2015;Calabrese et al 2015;Coutens et al 2022), acrylamide (C 2 H 3 C(O)NH 2 ; Kolesniková et al 2022), and vinyl alcohol (C 2 H 3 OH; Melosso et al 2019). The presence of the latter in the ISM, together with propenal (C 2 H 3 CHO), was announced in the past (Turner & Apponi 2001;Hollis et al 2004) but it has been unambiguously confirmed very recently (Agúndez et al 2021;Manigand et al 2021).…”