Ultrafast Multidimensional Fluorescence-Excitation Spectroscopy – 2D-FLEX

• Applicant: Professor Dr. Jürgen Hauer
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 548646502

Ultrafast spectroscopy is an indispensable research tool for understanding molecular dynamics and photochemical reactions. Modern techniques resolve their signals not only in time but also in multiple frequency dimensions. Two-dimensional electronic spectroscopy (2D-ES) reached the maximum information content by dispersing the signal in excitation and detection frequencies while retaining femtosecond time resolution. This completeness can, however, turn into a drawback: signals from 2D-ES may consist of a multitude of overlapping contributions, not all of which are relevant to photochemical reaction pathways. In this proposal, we address this challenge by devising a technique that retains both the multidimensional character and the superb time resolution of 2D-ES. We propose a new method where overlapping contributions are avoided by only detecting time-resolved fluorescence signals dispersed in excitation and detection frequency. This leads us to ultrafast two-dimensional fluorescence excitation spectroscopy (2D-FLEX). This novel technique offers femtosecond time resolution and a single contributing signal pathway exclusive to photochemically reactive excited states. 2D-FLEX will deliver a new level of clarity for convoluted and highly relevant processes such as singlet-to-triplet conversion in metal-organic complexes. The new method proposed here comprehensively describes fully resolved spectroscopic signals exclusive to electronic excited states with sub 80 femtosecond time resolution. The main objective is an unobscured perspective on excited state energy transfer in photochemically relevant complexes.

• DFG Programme: Research Grants
• International Connection: China, Czech Republic
• Co-Investigator: Terrance Hadlington, Ph.D.
• Cooperation Partners: Professor Dr. Maxim Gelin; Professor Dr. Frantisek Sanda