Collision-Induced Electronic Energy Transfer From v=0 Of The E(0g+) Ion-Pair State In I2: Collisions With I2(X)

The collision-induced electronic energy transfer that occurs when I 2 in the E(0 g ϩ) ion-pair electronic state collides with ground electronic state I 2 has been investigated. We prepare I 2 in single rotational levels in vϭ0 of the E state using two-color double resonance laser excitation. The resulting emission spectrum shows that the nearby (⌬T e ϭϪ385 cm Ϫ1) D(0 u ϩ) electronic state is populated. The cross section for collision-induced E→D energy transfer is found to be 18Ϯ3 Å 2. A range of D state vibrational levels are populated, consistent with a model in which overlap between the initial and final vibrational wave functions is important, but modulated by propensities for small vibrational energy gaps and those energy gaps that are closely matched to the vϭ0→vϭ1 energy separation in the I 2 (X) collision partner.