Two-dimensional electronic spectroscopy of bacteriochlorophyll a with synchronized dual mode-locked lasers

TL;DR

This paper introduces a dual mode-locked laser system enabling two-dimensional electronic spectroscopy of bacteriochlorophyll a, capturing both femtosecond vibrational spectra and nanosecond electronic relaxation, advancing the study of energy transfer in complex systems.

Contribution

The study develops and demonstrates a novel dual mode-locked laser-based 2DES technique capable of simultaneous high-resolution vibrational and long-timescale electronic measurements.

Findings

Successful measurement of vibrational spectra in bacteriochlorophyll a

Observation of nanosecond electronic relaxation dynamics

Potential applications in studying energy transfer in biological and material systems

Abstract

How atoms and electrons in a molecule move during a chemical reaction and how rapidly energy is transferred to or from the surroundings can be studied with flashes of laser light. However, despite prolonged efforts to develop various coherent spectroscopic techniques, the lack of an all-encompassing method capable of both femtosecond time resolution and nanosecond relaxation measurement has hampered various applications of studying correlated electron dynamics and vibrational coherences in functional materials and biological systems. Here, we demonstrate that two broadband (>300 nm) synchronized mode-locked lasers enable two-dimensional electronic spectroscopy (2DES) study of chromophores such as bacteriochlorophyll a in condensed phases to measure both high-resolution coherent vibrational spectrum and nanosecond electronic relaxation. We thus anticipate that the dual mode-locked laser-based 2DES developed and demonstrated here would be of use for unveiling the correlation between the quantum coherence and exciton dynamics in light-harvesting protein complexes and semiconducting materials.