Rotational Fingerprints of Vinylketene for Astronomical Observations

A high degree of isomerism in the realm of interstellar molecules stimulates systematic astronomical investigations of members of different families of isomers. Among them, vinyl-bearing compounds have kindled considerable interest due to recent detections of vinylamine, vinylacetylene, and vinylcyanoacetylene. Herein, we open the possibility to search for vinylketene in the interstellar space by means of its rotational transitions. The pure rotational spectrum of the title molecule was recorded in the frequency regions 195-218 and 293-324 GHz and an improved and extended set of spectroscopic parameters has been obtained for the most stable trans conformer. In addition, rotational signatures and molecular constants for the less stable cis form are reported for the first time. We provide a catalog of precise transition frequencies and intensities of vinylketene to the astronomical community and pave the way toward interstellar explorations of C4H4O isomer family.