Luminescence of ion-pair and spin-excited states of I2 in solid xenon

We report UV and visible molecular ion-pair emission upon 193 nm excitation of I2 in solid Xenon. By comparison to molecular emission observed in Kr matrices it is assigned to the δ(2u)→2g (I∗+I) and δ(2u)→2g (I+I) transitions. The solvation energy of this charge transfer state is surprisingly small, and the fluorescence is efficiently quenched when the sample temperature is raised. Population may partially flow into valence states correlating to the I∗+I∗ asymptotes. In contrast to all lighter matrices, I∗+I∗→I2 luminescence is observed upon excitation in the region of ion-pair absorption in solid Xe.