Intramolecular nuclear dynamics in intermolecular Coulombic electron capture

Abstract

We present an analytical model for intermolecular Coulombic electron capture (ICEC), which includes the internal nuclear dynamics of the molecules involved. In ICEC, an electron attaches to an atom or molecule by transferring excess energy to a neighbor, ionizing said neighbor. While previous theoretical investigations assumed fixed nuclei, recent studies indicate that relative motion between the two ICEC partners significantly influences the process. Here, we incorporate the internal nuclear motion of the molecules involved into an analytical equation of the ICEC cross section. We employ two approaches: (1) utilizing theoretical vibrationally resolved photoionization cross sections and (2) applying the Franck–Condon principle. Our theory yields electron spectra, ICEC cross sections for individual vibronic transitions, and temperature dependent cross sections. Nuclear dynamics lead to a distribution of the electronic cross section over several vibrational states and, in our model system H+ LiH, trigger dissociation of LiH during ICEC.