Laser induced fluorescence, energy transfer and dissociation of Cs2

Abstract

Laser induced fluorescences of Cs₂ excited by the Ar⁺ laser lines have been studied. A series of lines with vibrational progression and the successive diffuse bands in the region down to 16 200 cm⁻¹ were found to be polarized and identified as the resonance fluorescence. The diffuse fluctuation band with a maximum of intensity at 16 400 cm⁻¹ consists of several bands at regular interval and it was independent on the line of excitation. By applying the theory on the role of kinetic energy in the Franck–Condon principle proposed by Mulliken, the band was identified as a transition from the internuclear distance of maximum kinetic energy in the vibrational level of the excited state E ¹π_u. All the other fluorescence bands of low frequency were observed to be depolarized completely, and the intensities increased when a foreign gas was added. These bands were identified as the fluorescence from the states which were populated by collision‐induced transitions from the E state. Atomic fluorescence 6p ²P_3/2→6s ²S_1/2 is interpreted as the production of the excited atom Cs 6p ²P_3/2 by predissociation of Cs₂ E ¹π_u through interaction with, most probably, Cs₂ B ¹π_u.