2-COLOR DOUBLE-RESONANCE MULTIPHOTON IONIZATION SPECTROSCOPY OF S-2

The S-2 radical has been studied in a pulsed molecular beam via two-co lour multiphoton ionisation spectroscopy. This has resulted in the ext ended characterisation of the (3d pi)(3) Delta(g) Rydberg state, and o f the first observation of an ion-pair state, a (5) Sigma(g)(-), state . The two-colour transition involved the mixed B/B'' states of the rad ical as the intermediate level of the ionisation scheme. The bands rec orded showed sharp rotational structure, and spectroscopic constants f rom a rotational analysis of the spectra are presented.