Dynamical Jahn-Teller effects on the generation of electronic ring currents by circularly polarized light

TL;DR

This paper investigates how vibronic couplings, specifically Jahn-Teller effects, influence the generation and control of electronic ring currents in molecules using circularly polarized light, revealing suppression and wavelength-dependent directionality.

Contribution

It demonstrates that Jahn-Teller distortions significantly affect ring current generation, showing suppression effects and wavelength-dependent circulation directions, which were not previously understood.

Findings

Jahn-Teller effects suppress maximum ring currents by at least an order of magnitude.

The direction of electronic ring currents depends on the photon wavelength.

Vibronic couplings can reverse the circulation direction induced by circularly polarized light.

Abstract

The generation of electronic ring currents in ring-shaped molecules by photo-excitation with circularly polarized laser light is considered in the presence of vibronic coupling effects. $(E\times e)$ Jahn-Teller distortions, unavoidable by symmetry in the $(E)$ subset of electronic states supporting the ring current, mix the clockwise and anti-clockwise circulation directions of the electrons and can suppress the maximum achievable current by at least one order of magnitude, already for moderate vibronic coupling strengths, as compared to the Born-Oppenheimer limit of fixed atomic positions. The circulation direction of the electrons is found to depend on the spectral region of the $(E\times e)$ Hamiltonian. This fact results in the surprising effect that the same polarization direction of the laser pulse can trigger either clockwise or anti-clockwise electronic dynamics depending on the wavelength of the photons. These findings are illustrated in a model of the triazine molecule.