Near-resonant rovibronic Raman scattering from 0g+ (bb) valence state via the D0u+ ion-pair state in iodine molecule

Abstract

Near-resonant Raman scattering from the electronic excited \({I_2}\left( {0_g^ + \left( {bb} \right)\xrightarrow{{hv}}D0_u^ + \to X0_g^ + } \right)\) state via the intermediate ion-pair D0_u⁺ state to the X one is observed for the first time. The Raman scattering follows a laser pulse. Its intensity I_R is inversely proportional to the squared value of detuning from the resonant D, 22, 51 ← 0_g⁺(bb), 7, 52 transition, (Δν₂)², according to the theory of near-resonant Raman scattering. The ratio of Raman D → X scattering intensity to that of the D0_u⁺, ν_D = 22, J_D = 51 → X0_g⁺ luminescence, I_R/I_D‒X < 1.5 × 10^–4 for Δν₂ > 0.5 cm^–1. The Raman and luminescence spectra are found to be identical.