Fine structure in the A – X system of aluminium monochloride molecule, determination of dissociation energy by predissociation

¹ Spectroscopy Division. National Physical Laboratory, New Delhi, India.
² Laser and Spectroscopy Laboratory, Department of Physics Banaras Hindu University, Varanasi-221005, India.

Abstract

The rotational structure of the A — X system of aluminium monochloride molecule has been photographed in the third order of a 10.6 meter concave grating spectrograph with 0.22 Å/mm dispersion in order to obtain precise molecular constants. The rotational predissociation observed in the bands involving V = 9 and 10 vibrational levels of the excited state has been used to determine the precise value of the dissociation energy which comes out to be 5.26 ± 0.01 eV. The nature of the predissociating state has also been discussed.

Résumé

La structure rotationnelle du système A — X du monochlorure d'aluminium a été photographiée dans le 3^e ordre d’un réseau concave de rayon 10,6 m. de dispersion 0,22 Å/mm, afin d’obtenir des constantes moléculaires précises. La prédissociation rotationnelle, observée dans les niveaux ν = 9 et ν = 10 de l’état excité a servi à déterminer la valeur précise de l'énergie de dissociation, qui est de 5,26 ± 0,01 eV. On discute également la nature de l'état prédissociant.