Discrete and Diffuse Emission Following Two-Photon Excitation of theEState in Molecular Iodine

Abstract

We studied the fluorescence spectrum of $E\to B$ transitions in molecular iodine following two-photon absorption. Discrete re-emission lines terminating in $B$-state levels ranging from $v=0\mathrm{}$ to the dissociation limit were observed in addition to a series of broad diffuse lines. These diffuse lines represent the first observation of Condon "internal diffraction" resulting from a single vibronic state, and therefore the variation of the bands directly displays the variation of the Franck-Condon factor.