Dynamics of Single Molecule Stokes Shifts: Influence of Conformation and Environment

TL;DR

This study investigates how the Stokes shift in single molecules varies over time due to conformational changes and environmental factors, revealing their interplay through spectroscopic measurements.

Contribution

It provides new insights into the temporal dynamics of Stokes shifts in single molecules, highlighting the influence of conformation and environment.

Findings

Stokes shift varies between individual molecules and over time.

Fluctuations are linked to conformational and environmental changes.

Emission and excitation spectra shift unidirectionally during fluctuations.

Abstract

We report on time dependent Stokes shift measurements of single molecules. Broadband excitation and emission spectroscopy were applied to study the temporal Stokes shift evolution of single perylene diimide molecules (PDI) embedded in a polymer matrix on the time scale of seconds. The Stokes shift varied between individual molecules as well as for single molecules undergoing different conformations and geometries. From the distribution and temporal evolution of Stokes shifts, we unravel the interplay of nano-environment and molecular conformation. We found that Stokes shift fluctuations are related to simultaneous and unidirectional shifts of both emission and excitation spectra.