Knowledge Bank

Instead of describing molecular spectra in terms of electronic energy plus vibrational energy plus rotational energy, with rotational energy constants depending on vibrational quantum numbers; molecular spectra can be described in terms of electronic energy plus rotational energy with vibrational energy energy constants dependent on rational quantum numbers. This latter procedure provides a unique potential energy curve for each value of a rotational quantum number. The square array wave numbers for lines corresponding to vibrational quantum numbers $v\prime J\prime$ and $v\prime J\prime$ have constant separations of the wave number values in rows and in columns. Each line in a band provides a determination of $(\nu oo)J\prime J\prime$ so that the final average value of constants are expected to be more accurate than constants obtained by usual methods. A sample calculation for TlCl will be described.