Optical–optical double resonance study of the H' 1 (1D2) ion-pair state of I35Cl: Rovibrational structure and electronic transition dipole moment function

Abstract

The H' 1 (1D2) ion-pair state of I35Cl, which correlates to the I+ (1D2) + Cl− (1S0) dissociation limit, was analyzed spectroscopically by H' 1 (1D2) ← A3Π1 ← X1Σ+ optical–optical double resonance excitation. In total, 751 transitions covering 0 ≤ vH' ≤ 20 and 10 ≤ JH' ≤ 41 were observed. An e/f-parity splitting (Ω-type doubling) in the H' 1 (1D2) state was observed. By fitting 656 transitions to Dunham type expansion, Dunham coefficients for the H' 1 (1D2) state were determined to be Y00 = 51615.194(14), Y10 = 184.2440(59), Y20 = −0.63083(67), Y30 = 0.001400(21), Y01 = 0.05780468(82), Y11 = −2.2465(19) × 10−4, and Y21 = −2.227(88) × 10−7 cm−1. The vibration-dependent Ω-type doubling constants were determined to be q0 = 1.97(17) × 10−5, q1 = 8.76(38) × 10−6, and q2 = −3.498(18) × 10−7 cm−1. The electronic transition dipole moment function of the H' 1 (1D2) – A3Π1 transition in the range of 2.977–3.683 Å was determined experimentally by analyzing the dispersed ultraviolet (UV) fluorescence spectra combined with the fluorescence lifetime of the H' 1 (1D2) state.