Shaping excitons in light-harvesting proteins through nanoplasmonics

TL;DR

This study demonstrates how nanoplasmonics can be used to selectively excite and probe individual pigments within light-harvesting proteins, enabling detailed investigation of quantum processes in biological systems.

Contribution

The paper introduces a multiscale quantum chemical model showing that tip-shaped metal nanoparticles can target specific regions of light-harvesting complexes for enhanced spectroscopic analysis.

Findings

Selective excitation of individual pigments achieved

Potential to observe quantum diffusion processes

Enhanced spatial resolution in spectroscopic measurements

Abstract

Nanoplasmonics has been used to enhance molecular spectroscopic signals, with exquisite spatial resolution down to the sub-molecular scale. By means of a rigorous, state-of-the-art multiscale model based on a quantum chemical description, here we show that optimally tuned tip-shaped metal nanoparticles can selectively excite localized regions of typically coherent systems, eventually narrowing down to probing one single pigment. The well-known major light-harvesting complex LH2 of purple bacteria has been investigated because of its unique properties, as it presents both high and weak delocalization among subclusters of pigments. This finding opens the way to the direct spectroscopic investigation of quantum-based processes, such as the quantum diffusion of the excitation among the chromophores, and their external manipulation