Rotational analysis of the B3Π(0+) → X1Σ+ band systems of 35Cl35Cl and 35Cl37Cl in the chlorine afterglow emission spectrum

Abstract

The B3Π(0+) → X1Σ+ band system of Cl2, excited by the recombination of ground state Cl2P32 atoms at total pressures near 2 Torr, has been rotationally analyzed in the range 6300–9900 Å. About 30 bands, with 0 ≤ v′ ≤ 6 and 5 ≤ v″ ≤ 14, were investigated, mostly for both 35Cl35Cl and 35Cl37Cl. The band origins and rotational constants for the B state were obtained with the help of the known constants for the ground state. The principal molecular constants (cm−1) for the B3Π(0+) state of 35Cl35Cl are as follows: Te′ = 17 817.67(3); ωe′ = 255.38(3); ωe′xe′ = 4.59(1); ωe′ye′ = −0.038(8); De′ = 3341.17(14); Be′ = 0.16313(3); αe′ = 2.42(3) × 10−3; γe′ = −5.7(7) × 10−5. The equilibrium internuclear separation is 2.4311(2) Å. The results of Briggs and Norrish on a transient absorption spectrum of Cl2 assigned as 0g+ ← B3Π(0+) are reinterpreted with the present constants.