Study of the 7¹Π _u state of sodium dimer by polarisation labelling spectroscopy

Abstract

Two-colour polarisation labelling experiment measuring excitation spectra of Na${}_2$ in the spectral range 34, 600−39, 400 cm${}^{-1}$ has furnished observation of the previously unknown $7^1{\mathrm{\Pi }}_u$ electronic state. The excited state is characterised by a set of Dunham coefficients describing the f parity levels up to vibrational level v = 28 and the corresponding potential energy curve is constructed by the inverted perturbation approach method. Molecular parameters determined in the fit include $T_e=36583.86$ ± 0.03 cm${}^{-1}$, ${\omega }_e=107.50$ ± 0.03 cm${}^{-1}$ and $R_e=3.640$ ± 0.001 Å.

GRAPHICAL ABSTRACT

Keywords:

• Laser spectroscopy
• alkali dimers
• electronic states
• molecular constants
• potential energy curves

Acknowledgments

This article is dedicated to the late Professor Lutosław Wolniewicz in recognition to his outstanding contribution to quantum chemistry and molecular physics.

Disclosure statement

No potential conflict of interest was reported by the author(s).