Laboratory Detection of the Ring-Chain Molecule C[TINF]7[/TINF]H[TINF]2[/TINF]

Open Access
Publisher Website
Google Scholar
Abstract
Following the recent laboratory detection of the ring-chain carbene C5H2, we have now detected C7H2, the next longer member of the sequence formed by substituting a carbon chain for one of the hydrogen atoms of cyclic C3H2. The strongest lines, again obtained with a diacetylene-neon discharge, were roughly 15 times weaker than those of C5H2. Enough rotational lines were detected in both the normal and doubly deuterated isotopic species to be certain of the identification and to obtain the rotational and leading centrifugal distortion constants accurately enough for calculation of the entire rotational spectrum below 300 GHz to a fraction of 1 km s-1 in equivalent radial velocity. The ring chain here is calculated to be the most stable isomer of C7H2 and extremely polar, so it is of considerable astronomical interest. Several other isomers of C7H2 may be detectable in the laboratory and in space with present techniques.