10min:
FOURIER-TRANSFORM SPECTROSCOPY OF I2 (D-X) EMISSION FOLLOWING OPTICAL-OPTICAL DOUBLE RESONANCE EXCITATION OF THE I2 (E) STATE.

VADIM A. ALEKSEEV, Institute of Physics, St.Petersburg State University, Peterhof, 198504 Russia; AMANDA J. ROSS, Laboratoire de Spectrométrie Ionique et Moléculaire, Université' de Lyon (Lyon 1), 69622 Villeurbanne, France.

The E 0+g ion-pair state of I2 molecule may be excited by the optical-optical double resonance (OODR) via the valence state B 0+u,

I2(X 0+g) + hv1 rightarrow I2 (B 0+u ) + hv2 rightarrow I2 ( E 0+g ).

Emission spectra of pure I2 vapor selectively excited in this way show not only ransitions from the E 0+g state, but also D 0+u rightarrow X 0+g transition in the near ultraviolet. Typically the populated levels in the D 0+u state are located less than ~ 300 cm-1 below the laser-excited level. In this contribution we examine rotationally resolved Fourier-transform spectra of the D 0+u rightarrow X 0+g emission following OODR excitation of various E 0+g v, J levels with single mode cw dye lasers. We show that the E 0+g rightarrow D 0+u population transfer obeys the JD=JE +- 1, 3, 5 ... propensity rule. Transfer to the JD=JE +-1 levels is the most probable although in some cases, JD=JE-1 and JD=JE+1 have significantly different populations.