Rotationally resolved optical-optical double resonance study of the f′ 0+ (1D2) ion-pair state of I35Cl

The f′ 0+ (1D2) ion-pair state of I35Cl, which correlates to the I+ (1D2) + Cl− (1S0) dissociation limit, was analyzed by an optical-optical double resonance scheme through the B3Π(0+) state as an intermediate state. In total, 442 transitions in the range of 2 ≤ vf′ ≤ 17, 13 ≤ Jf′ ≤ 50 were identified. Dunham coefficients for the f′ 0+ (1D2) ion-pair state were determined to be Y00 = 51200.42(13), Y10 = 160.599(50), Y20 = −0.1760(55), Y30 = −0.00216(18), Y01 = 0.05908(17), Y11 = −1.284(39) × 10−4, Y21 = −2.37(19) × 10−6, and Y02 = −3.198(16) × 10−8 cm−1. An RKR potential of the f′ 0+ (1D2) ion-pair state is constructed based on these constants. [Display omitted] •The f′ 0+ (1D2) ion-pair state of I35Cl was populated by two-step laser excitation method.•The absolute numbering of the vibrational levels was performed through the analyses of the fluorescence.•The Dunham-type constants were determined through the analyses of 442 rotationally-resolved vibronic transitions.•An accurate potential energy curve was constructed.