Nonadiabatic electronic interactions in the ion-pair states of NeICl

Abstract

Nonadiabatic interactions in the NeICl van der Waals complex have been explored in the lowest energy triad of ICl ion-pair states (∼39 000 cm−1). Dispersed fluorescence measurements reveal emission characteristic of multiple ion-pair electronic states, with the relative contributions from the E(0+), β(1), and D′(2) states changing with the initial ICl vibrational excitation (vICl). Emission directly from NeICl (vICl=0) complexes indicates that the initially prepared NeICl levels have mixed electronic character and that the ICl electronic parentage changes with the initial van der Waals vibrational level selected. NeICl complexes prepared with 1–4 quanta of ICl stretch undergo rapid vibrational predissociation with a strong propensity for ΔvICl=−1 relaxation. The electronic state(s) populated in the ICl fragments differ from the mixed electronic character of the initially prepared level, demonstrating that vibrational predissociation is accompanied by nonadiabatic electronic state changing processes. The observed final state selectivity may be attributed to the relative strength of the nonadiabatic couplings between the initial NeICl bound state and the final ICl states or a momentum gap rationale based on the overlap between the NeICl bound state wave function and the highly oscillatory continuum wave function of the separating fragments.

The van der Waals potential energy surfaces and structures of He–ICl and Ne–ICl clusters

“…21 In turn, the value for the near T-shaped Ne-ICl binding energy is larger than an early experimental estimation 33 but in good accord with later reported experimental values. 34,36 For the Rg-ICl complexes studied, the present surfaces are the first ab initio ones available and the comparison with experimental data demonstrates the high quality of them. Using these CCSD͑T͒ surfaces, work is in progress to study the dynamics and spectra of the He-ICl and Ne-ICl complexes.…”

“…This leads to larger values of dissociation energy of Ne-ICl in the A and X electronic states than the ones previously estimated. 33 Thus, a higher value of D 0 Ϸ60 cm Ϫ1 has been adopted 34,36 for the bond energy of Ne-ICl in A state, implying an upper value of D 0 ϭ70Ϯ5 cm Ϫ136 for the dissociation energy of the Ne-ICl ground state. The present CSSD͑T͒ result of D 0 ϭ65.2 cm Ϫ1 is consistent with this experimental estimate.…”

Experimental interrogation of the multidimensional He+ICl(E,v†) and He+ICl(β,v†) intermolecular potential energy surfaces

“…12 No fluorescence signals were observed for transition energies above these features, which include the Ϸ45 cm −1 region between the Ne+ I 35 Cl͑E , v † =0͒ and the higher-lying Ne +I 35 Cl͑␤ , v † =0͒ dissociation limits. 12 No fluorescence signals were observed for transition energies above these features, which include the Ϸ45 cm −1 region between the Ne+ I 35 Cl͑E , v † =0͒ and the higher-lying Ne +I 35 Cl͑␤ , v † =0͒ dissociation limits.…”

“…Stephenson et al 12 reported on the varying nonadiabatic electronic interactions in different intermolecular vibrational levels bound within the Ne+ I 35 Cl͑␤ , v † =0-4͒ potentials. These interactions were characterized by recording two- …”

“…12 In the highest energy regime, the metastable Ne¯I 35 Cl͑␤ , v † =0͒ intermolecular levels could promptly couple to the Ne+ I 35 Cl͑E , v † =0͒ and Ne +I 35 Cl͑DЈ , v † =0͒ continua of states. 12 In the highest energy regime, the metastable Ne¯I 35 Cl͑␤ , v † =0͒ intermolecular levels could promptly couple to the Ne+ I 35 Cl͑E , v † =0͒ and Ne +I 35 Cl͑DЈ , v † =0͒ continua of states.…”