Knowledge Bank

Oka and coworkers1 have detected $C2H3\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ by high-resolution infrared spectroscopy around 3 umm; their preliminary analysis suggested that the species detected is the non-classical(bridged) form. We are endeavouring to observe the perpendicular C-H (bridge) stretch band $(\nu 2)$ of nonclassical $C2H3+$ around $5\mu n$. An initial search was made in $2020-2080cm-1$ region with diode lasers and a cooled hollow cathode discharge in a mixture of $C2H2$ and $H2$. Several series of lines were detected. Although the assignment is not definitive, the species detected in this search is tentatively identified as $C2H3$ on the basis of the observed chemistry and the line spacings. Oka, Phil. Trans. Roy. Soc. London, to be published.