Analysis of the Jahn-Teller effect in then p 2 E′ Rydberg series of H3 and D3

Abstract

Spectroscopic signatures of Jahn-Teller (JT) coupling in the np~,.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 JTinduced effects are shown to exhibit a characteristic dependence on the vibrational angular momentum of the bending mode in the initial state.

The Jahn–Teller effect in the 3 pe ′ Rydberg state of H 3 : review of experimental and ab initio determinations

“…As may be seen from the table, a reassuring outcome of the present analysis is the fact that the linear JT (f ) splitting parameter values determined by various authors are all consistent to within about 10 per cent. Moreover, the f value extracted by Staib & Domcke [7] from the frozen-core surface of Nager & Jungen [8] is found to agree to within 1 per cent with the value derived here from the correlated calculation of Mistrík et al [6]. Judging from equation (1.1), we conclude that the corresponding DR cross sections should agree to within 2 per cent.…”

“…The theory presented in Kokoouline et al [1] and dos Santos et al [2] is based on ab initio computations of bound n = 4 Rydberg states of H 3 by Mistrík et al [6], from which the static linear JT splitting was extracted, using a procedure initiated by Staib & Domcke [7] (who based their work on earlier ab initio computations of Nager & Jungen [8] for n = 3). This information then subsequently served to compute the dynamical electron capture process by the positive ion, followed by neutral molecular dissociation [2].…”

Dissociative Recombination of Highly Symmetric Polyatomic Ions

“…Fortunately, it is possible to construct a model Hamiltonian (similar to the one constructed in [14][15][16]) for the electron-ion interaction in the diabatic representation. The same representation can then be used to construct the model matricesμ(Q) orν(Q) , which are not diagonal (as in any diabatic representation) and contain a few parameters that can be fitted to reproduce ab initio energies.…”

Vibrational autoionization in polyatomic molecules

“…The overall rovibronic symmetry of the electronion complex is preserved in this process: Even though the vibrational symmetry changes by a factor of e (through the loss of one quantum of the e vibration), the rotational symmetry also changes by a factor of e in going from K + = 2 to K + = 0. The important point is that the Jahn-Teller interaction provides a mechanism for efficient vibrational autoionization via nontotally symmetric vibrations (31). Thus, for the npe series, resonances analogous to the extremely sharp npa 2 resonance in Figure 8a can actually decay quite rapidly.…”

“…Interestingly, whereas the npe series converging to the H + 3 (v 1 > 0, v 2 • ) N + = 1, K + = 0 levels can autoionize just as the N = 0, npa 2 series do by v 1 = −1 processes, the npe series converging to the (v 1 , v 2 1 ) N + = 2, K + = 2 levels can autoionize by a v 2 = −1 process that is forbidden for the np a 2 series (31)(32)(33)(34). This process is driven by the Jahn-Teller interaction and can be viewed as an npe , = ±1 electron scattering off the H + 3 (v 1 , v 2 1 ) N + = 2, K + = 2 core and de-exciting it to the H + 3 (v 1 , (v 2 -1) 0 ) N + = 1, K + = 0 level, with a concurrent flip of = ±1 to = ∓1.…”