Bonding in light-induced vortices: benzene in a high-frequency circular polarized laser

TL;DR

This study explores how high-frequency circularly polarized lasers induce unique vortex states in benzene, leading to stable, doubly-aromatic electronic structures with potential experimental realization and implications for harmonic generation.

Contribution

It reveals the formation of light-induced vortex states in benzene under high-frequency circularly polarized lasers, introducing a novel stable electronic configuration with doubly-aromatic characteristics.

Findings

Formation of circular current rings at each carbon atom.

Creation of a deep vortex supporting bound electron pairs.

Minimal ionization with sudden laser pulse rise-time.

Abstract

The electronic structure of benzene in the presence of a high-intensity high-frequency circularly polarized laser supports a middle-of-the-ring electron localization. Here, the laser polarization coincides with the ring plane of benzene. The high-frequency oscillating electric field creates circular currents centered at each atom with a circle radius equal to the maximum field amplitude of the laser. All six carbons have six such rings. For a maximum field amplitude of 1.42 {\AA}, which is the carbon-carbon bond distance, all six dynamic current circles intersect to create a deep vortex in the middle, which supports a bound state of a pair of electrons. Such states for benzene can be realized in experiments using a circularly polarized XUV-laser in a range of intensities 10^16-10^17 W/cm^2 and frequencies 16 eV to 22 eV. Electronic dynamics calculations predict a minimal ionization of benzene when the rise-time of the laser pulse is sudden, indicating a possible experimental realization of these states characterized by a large cut-off in the harmonic generation spectra. This stable electronic structure of the light-dressed benzene is doubly-aromatic due to an extra aromaticity from a D6h symmetric circular distortion of the{\sigma}-framework while the {\pi}-electrons, with low density in the ring-plane,are least affected.