Analysis of the Jahn-Teller effect in the n p²E′ Rydberg series of H₃ and D₃

Spectroscopic signatures of Jahn-Teller (JT) coupling in the n p_x,y²E′ Rydberg series of H₃ and D₃ are analyzed within a simple multi-channel-quantum-defect-type model. The JT coupling constant has been inferred from existing ab initio calculations of the potential-energy surfaces of low Rydberg states of H₃. The model predicts pronounced resonant perturbations in Rydberg members with intermediate n (n=5-7) as well as strong JT-induced autoionization in absorption and ion-yield spectra from vibrationally excited initial levels. The JT-induced effects are shown to exhibit a characteristic dependence on the vibrational angular momentum of the bending mode in the initial state.