Recollision-Induced Plasmon Excitation in Strong Laser Fields

TL;DR

This paper reveals a new recollision pathway in multielectron systems like C60, where returning electrons excite collective modes, potentially overshadowing harmonic generation and affecting tomographic imaging.

Contribution

It introduces an analytical theory predicting recollision-induced collective mode excitation dominates harmonic yield in multielectron targets at certain wavelengths.

Findings

Recollision can excite collective modes in multielectron systems.

Longer wavelengths make the dynamics more single-electron-like.

Recollision-induced excitation may obscure tomographic imaging.

Abstract

Recolliding electrons are responsible for many of the interesting phenomena observed in the interaction of strong laser fields with atoms and molecules. We show that in multielectron targets such as C60 a new important recollision pathway opens up: the returning electron may excite collective modes even if the laser frequency is far off-resonant. We formulate a simple analytical theory which predicts that the recollision-induced excitation of collective modes should dominate over the "usual" harmonic generation yield at 800nm wavelength. In this case the tomographic imaging of complex multielectron systems may be obscured. We employ a time-dependent density functional model of C60 and show that with increasing laser wavelength the dynamics becomes more and more single active electron-like, suggesting that long wavelengths are to be preferred for imaging purposes.