Room-temperature ultrafast non-linear spectroscopy of a single molecule

TL;DR

This paper presents the first ultrafast time-resolved spectroscopy on a single molecule at room temperature, revealing its non-linear ultrafast electronic response with 25 fs resolution, enabling 2D electronic spectroscopy at the single-molecule level.

Contribution

It introduces a novel ultrafast transient spectroscopy technique for single molecules, overcoming previous static limitations and opening new avenues for molecular dynamics studies.

Findings

First ultrafast transient spectroscopy on a single molecule at room temperature

Demonstration of 25 fs temporal resolution in single-molecule spectroscopy

Potential for two-dimensional electronic spectroscopy of single molecules

Abstract

Single molecule spectroscopy aims at unveiling often hidden but potentially very important contributions of single entities to a system's ensemble response. Albeit contributing tremendously to our ever growing understanding of molecular processes the fundamental question of temporal evolution, or change, has thus far been inaccessible, resulting in a static picture of a dynamic world. Here, we finally resolve this dilemma by performing the first ultrafast time-resolved transient spectroscopy on a single molecule. By tracing the femtosecond evolution of excited electronic state spectra of single molecules over hundreds of nanometres of bandwidth at room temperature we reveal their non-linear ultrafast response in an effective 3-pulse scheme with fluorescence detection. A first excitation pulse is followed by a phase-locked de-excitation pulse-pair, providing spectral encoding with 25 fs temporal resolution. This experimental realisation of true single molecule transient spectroscopy demonstrates that two-dimensional electronic spectroscopy of single molecules is experimentally in reach.