Multistate and multimode vibronic dynamics: The Jahn–Teller and pseudo-Jahn–Teller effects in the ethane radical cation

摘要: Abstract Multimode Jahn–Teller (JT) and pseudo-Jahn–Teller (PJT) coupling effects in the photoelectron spectrum of ethane are theoretically investigated. In this article, we focus on vibronic structure second excited B ∼ 2 E u electronic manifold radical cation which reveals an asymmetric band 14.5–16.5 eV ionization energy range experimental recordings. Ionization electron from third occupied 1eu molecular orbital produces degenerate manifold, is prone to JT instability when distorted along eg vibrational modes. The theoretical formalism employed here based a model diabatic Hamiltonian quadratic scheme with parameters derived ab initio calculations. calculated by carrying out quantum dynamical simulations coupled states. estimated be ∼2.75 eV ∼2.40 eV above its X g A 1 states, respectively. symmetry selection rule suggests PJT these states modes eg/eu symmetry. simulated within shows two maxima at ∼ 14.96 eV ∼15.76 eV attributed split adiabatic sheets manifold. This good accord their position observed ∼15.0 eV ∼15.8 eV, respectively, recording. diffuse overall can accounted large extent considering - interactions. shape agrees very well results. Further refinement results may accomplished including interactions model. Importance latter also discussed text.