DIFFERENCE FREQUENCY LASER SPECTROSCOPY OF $HCNH^{+}$: OBSERVATION OF SEVERAL ISOTOPIC SPECIES AND HOT BANDS

Abstract

The $\nu_{1}$ and $\nu_{2}$ fundamental bands of $HCNH^{+}$ and the $\nu_{1}$ fundamental band of $DCNH^{+}$ were recently observed in the laboratory by difference frequency laser spectroscopy. In the present work, measurements of the hot bands $(\nu_{1} + \nu_{4} \leftarrow, \nu_{1} + \nu_{5} \leftarrow \nu_{5})$ have been made possible with a hollow-cathode discharge cell. Also the measurement has been extended to the isotopic species, $HCND^{+}$ and $H^{13}CNH^{+}$. By combining these data with the already existing data on the normal species and $DCNH^{+}$, the $r_{s}$ structure of this ion has been obtained with the aid of the first moment condition. The bond lengths are in very good agreement with the calculated values $(r_{e})$ by Botschwina.