Collision-induced fluorescence of Cs2: the 3 1Σu+ → X1Σg+ system

We report the observation of a band system between 510 and 540 nm in laser induced fluorescence spectra of Cs2 excited by Ar+ laser lines λexc = 488 nm, λexc 496.5 nm and λexc = 501.7 nm. Using potential energy curves of Cs2 and performing quantum mechanical simulations of the spectra we assign these new structures to the transition 3 1Σu+ → 1 1Σg+.