A spectroscopic study of the E(0+g ) state of Cl2 by optical–optical double resonance

Abstract

An optical–optical double resonance (OODR) technique has been applied to study the E(0+g ) ion-pair state of Cl2 correlating with Cl−(1S)+Cl+(3P2). Observations were made on the v′=0 through v′=23 levels of the 35Cl2 isotope species. A set of Dunham molecular constants was derived by a global weighted least squares fit of 474 transitions (all in cm−1 and 3σ in parentheses): Y00=57 819.366(38), Y10=251.954(15), Y20=−1.0318(19), Y30=2.235(64)×10−3, Y01=0.116 556(62), Y11=−6.403(56)×10−4, and Y02=−4.8(37)×10−8. The emission spectra of the E(0+g )–B 3Π(0+u ) system observed in the OODR experiments were interpreted on the basis of Franck–Condon factor calculations, which established the absolute v′ numbering of the E(0+g ) ion-pair state.