Knowledge Bank

The new hollow-cathode discharge source described at previous Symposia1 gives many infrared lines of the $H3$ neutral molecule as well as of the vibration-rotation spectrum of the $H3+ion2$. The former are mostly lines of the known $3s2A1\to 3p2E\prime$ and $3d(2AJ\prime ,2E\prime \prime ,2E\prime )\to 3p2E\prime$ electronic $transitions3,4$, but the higher rotational temperature in the new source makes it possible to extend the previous assignments to higher N levels. The quality of the fit of the spectrum is not significantly improved by introducing additional parameters, suggesting that there are many small but irregular perturbations. A new group of lines near 4300 cm-1 is assigned to the electronic transition $4p2E\prime \to 3s2Aj\prime$, This is the first observation of an $n=4$ state of $H3$. $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ papers TE7 (1985) and RE5 (1986). $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ W.A. Majewski, M.D. Marshall, A.R.W. McKellar, J.W.C. Johns, and J.K.G. Watson, J. Mol. Spectrosc., in press. $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ G. Herzberg, H. Lew, J.J. Sloan, and J.K.G. Watson, Can. J. Phys. 59, 428 (1981). $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}$ G.Herzberg, J.T. Hougen, and J.K. G. Watson, Can. J. Phys. 60. 1261 (1982).