Optical-Optical Double-Resonance Spectroscopy of the 1u(3P2) and 2u(3P2) States of I2 Through the A3Π(1u) State

Abstract

Abstract Optical-optical double-resonance spectroscopy is used to study the 1u(3P2) and 2u(3P2) ion-pair states of I2 correlating to the lowest ionic state, I-(1S) + I+(3P2). In the (1 + 2) photoexcitation sequence, we gain access to the 1u(3P2) ion-pair state through the A3Π(1u) state. The 2u(3P2) state is also identified from the occurrence of extra lines through heterogeneous coupling with the 1u(3P2) state and an apparent energy shift in the 1u(3P2) state. The energy levels of the 1u(3P2) and 2u(3P2) states were analyzed in detail by including the heterogeneous interaction between these states. We have established the vibrational numbering of the 2u(3P2) state in considering the 1u-2u(3P2) interaction terms under a pure precession approximation. Combined with other results, the present study has allowed us to characterize and map out the ion-pair states of I2 in the 5 eV region.