Disentangling Single- and Biexciton Dynamics with Photoelectron-Detected Two-Dimensional Electronic Spectroscopy

TL;DR

This paper demonstrates that time gating and kinetic-energy filtering in photoelectron-detected 2D spectroscopy can disentangle complex exciton dynamics, including annihilation processes, providing insights comparable to coherent detection methods.

Contribution

The study introduces numerical simulation protocols showing how time gating and kinetic-energy filtering enhance photoelectron-detected 2D spectroscopy to resolve specific excited-state and annihilation dynamics.

Findings

Time gating extracts information similar to coherent 2D spectroscopy.

Kinetic-energy filtering isolates specific excited-state dynamics.

Simulations confirm the effectiveness of these methods in complex systems.

Abstract

Action-detected two-dimensional (2D) spectroscopy resolves the time-dependent nonlinear optical response of a quantum system by recording incoherently detected observables such as fluorescence, photoelectrons, or photocurrents which reflect the system's excited-state population. Processes such as exciton-exciton annihilation alter this population and obscure, for instance, energy transfer processes. This limits the information available from action-detected 2D spectra compared to their coherently detected counterparts. Here we investigate time gating and kinetic-energy filtering in photoelectron-detected 2D spectroscopy to disentangle various processes. We implement a numerical simulation protocol that allows us to calculate photoelectron-detected 2D spectra for various systems, demonstrating that time gating can extract the same information as coherently detected 2D spectroscopy, even when annihilation is present. Furthermore, we can directly infer annihilation dynamics. Kinetic-energy filtering additionally enables the isolation of specific excited-state dynamics. Our simulations demonstrate that time gating and kinetic-energy filtering are promising extensions for photoelectron-detected 2D spectroscopy.