Intense high-order harmonic generation in giant fullerene molecule C$_{240}$

TL;DR

This study models high-order harmonic generation in the giant fullerene molecule C240 under strong laser fields, highlighting the importance of electron-electron interactions and symmetry breaking effects.

Contribution

It introduces a detailed quantum nanostructure model of C240, incorporating many-body Coulomb interactions and vacancy effects, to analyze nonlinear optical responses.

Findings

Many-body Coulomb interactions significantly influence harmonic intensities.

Vacancy defects induce intense even-order harmonics by breaking symmetry.

Harmonic cutoff depends on laser intensity and frequency, revealing multiphoton resonance.

Abstract

In this work the extreme nonlinear optical response of a giant fullerene molecule C$_{240}$ in strong laser field is studied. The investigation of high-order harmonic generation in such quantum nanostructure is presented modeling the C$_{240}$ molecule and its interaction with the laser field in the scope of the tight-binding mean-field approach. Electron-electron interaction is modeled by the parametrized Ohno potentail, which takes into account long-range Coulomb interaction. The essential role of many body Coulomb interaction in determining of harmonics intensities is demonstrated. We also consider vacancy-deffected molecule C$_{240}$. The presence of a single vacancy breaks the icosahedral symmetry leading to the emergence of intense even-order harmonics. We examine the dependence of moderate harmonics on laser frequency that shows the multiphoton resonant nature of high harmonics generation. The dependence of cutoff harmonics on both laser intensity and frequency are examined too.