Knowledge Bank

Absorptions arising from the $A~-X~$ transition of normal and isotopically substituted NO$3$ have been observed between 7500 and 9500 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$. Details of the spectra will be discussed and assignments will be proposed. Absorptions arising from the $B~-X~$ transition of NO$3$, with band origin near 15 000 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$, have also been observed for the normal species and two of its isotopologues which possess D symmetry. As in the gas phase, the absorptions are broadened because of predissociation. The observed band structure corresponds closely with that reported for the gas-phase molecule.