Discovery in space and in laboratory of H2CCCN

This species was produced in the laboratory by an electric discharge of a gas mixture of vinyl cyanide, CH_2_CHCN, and Ne, and its rotational spectrum was characterized using a Balle-Flygare narrowband-type Fourier-transform microwave spectrometer operating in the frequency region of 8-40GHz. The observed spectrum shows a complex structure due to tunneling splittings between two torsional sublevels of the ground vibronic state, 0+ and 0-, derived from a large-amplitude inversion motion.

In addition, the presence of two equivalent hydrogen nuclei makes necessary to discern between ortho- and para-H_2_CCCN. A least squares analysis reproduces the observed transition frequencies with a standard deviation of ca. 3kHz. Using the laboratory predictions, this radical is detected in the cold dark cloud TMC-1 using the Yebes 40m telescope and the QUIJOTE line survey.