Photoinduced Fano-resonance of coherent phonons in zinc

TL;DR

This study investigates how femtosecond laser pulses induce Fano-resonance in zinc's coherent phonons, revealing excitation-dependent asymmetry linked to phonon-electron coupling near structural transitions.

Contribution

It demonstrates the observation of photoinduced Fano-resonance in zinc and models the asymmetric phonon spectra using the Fano function, highlighting excitation fluence effects.

Findings

Fano resonance appears at high excitation levels with asymmetric spectral line shapes.

The Fano parameter varies strongly with excitation fluence.

Coupling between coherent phonons and electronic continuum is responsible for the resonance.

Abstract

Utilizing femtosecond optical pump-probe technique, we have studied transient Fano-resonance in zinc. At high excitation levels the Fourier spectrum of the coherent E$_{2g}$ phonon exhibits strongly asymmetric line shape, which is well modeled by the Fano function. The Fano parameter (1/Q) was found to be strongly excitation fluence dependent while depending weakly on the initial lattice temperature. We attribute the origin of the Fano-resonance to the coupling of coherent phonon to the electronic continuum, with their transition probabilities strongly renormalized in the vicinity of the photoinduced structural transition.