Observation of Resonance Raman Scattering below the Dissociation Limit in I2 Vapor

Inelastic photon scattering from I₂ vapor was observed to change from resonance Raman scattering to resonance fluorescence as a single-mode argon laser was tuned through the 5145-Å gain profile. 3 orders of magnitude enhancement in the Stokes and the first-overtone intensities were measured in going from resonance Raman scattering to resonance fluorescence. The intensity distribution of the first 47 overtones is shown for the laser frequency coincident with the 43-->0 P(12) and 43-->0 R(14) transitions of B³Π0u+-->X¹Σ0g+. The resonance Raman cross section of I₂ compared with N₂ was found to be 2.6 × 10⁶.