At LSU, I am responsible for the research activities at its LOUVRE laboratory, which stands for Lots Of UV–Radiation for your Experiments. In the spirit of this name, we develop femtosecond laser pulse sources and ultrafast spectroscopy setups in the deep-UV spectral region, down to 250 nm. This lets us access important UV-chromophores, such as amino acid residues in proteins and peptides, the nucleobases in DNA-systems, organic ligands in metal complexes and large bandgap transitions in transition metal oxides. Our time-resolved deep-UV spectroscopy tools allow us to capture the dynamic response of these chromophores with femtosecond (10^-15 second) resolution and investigate the fastest chemical and biological processes taking place in the systems they are embedded in. Typically, these include energy and charge transfer processes and conformational changes in biological systems and charge separation and injection processes in metal-complexes and metal-oxides. Our work therefore aims to contribute to our fundamental understanding of the functioning of biological and chemical systems, such as proteins, and electronic processes in novel materials, which are important for solar cell development, for example.
My own research focusses on using the polarization of light to capture the fastest structural changes in the above systems in real-time, with femtosecond resolution. For this I have developed a time-resolved circular dichroism setup that is currently unique worldwide in its broadband detection in the deep-UV, spanning 250 – 370 nm. With this setup, we are capturing ultrafast chirality changes in (photo-)excited molecular systems in solution, which gives us direct access to their conformational dynamics. This perspective is especially relevant for understanding the dynamic relationship between structure and function in proteins and the kinetics of novel synthetic molecular machines, such as unidirectional molecular motors. In addition, we are applying the setup’s unique capability of capturing the chirality of electronically excited states to study materials for light-emitting diodes (LEDs), where the chirality of the emitting state causes strong circularly polarized luminescence.
By Malte Oppermann