Nonlinear terahertz polarizability of electrons solvated in a polar liquid

TL;DR

This study investigates the nonlinear terahertz response of solvated electrons in liquid 2-propanol, revealing coherent polaron oscillations at 3.9 THz and their phase modulation by off-resonant THz pulses, supported by theoretical modeling.

Contribution

It demonstrates the nonlinear terahertz polarizability of solvated electrons and provides a combined experimental and theoretical analysis of polaron dynamics.

Findings

Coherent polaron oscillations at 3.9 THz observed

Off-resonant THz pulses modulate polaron phase

Theoretical calculations reproduce nonlinear response

Abstract

The nonlinear polaronic response of electrons solvated in liquid 2-propanol is studied by two-dimensional terahertz spectroscopy. Solvated electrons with a concentration of c$_e \approx$ 800 $\mu$M are generated by femtosecond photoionization of alcohol molecules. Electron relaxation to a localized ground state impulsively excites coherent polaron oscillations with a frequency of 3.9 THz. Off-resonant perturbation of the THz coherence by a pulse centered at 1.5 THz modifies the polaron oscillation phase. This nonlinear change of electron polarizability is reproduced by theoretical calculations.