White Light Excited Two-Dimensional Fluorescence Excitation Spectroscopy: Picosecond Time-Resolved Excitation Emission Matrix

Two-dimensional electronic spectroscopy (2DES) has been widely employed to probe the dynamics of electronic excitations. However, conventional 2DES often encounters challenges in spectral assignment due to the intrinsic limitations of transient absorption detection. To overcome these issues, fluorescence-detected 2DES has been anticipated, and broadband excitation sources can enhance its performance. In this study, we have developed a two-dimensional fluorescence excitation (2DFLEX) spectroscopy by combining white-light excitation with Kerr-gate detection. This approach exploits the white light generated from a high-repetition-rate Yb-amplifier laser, providing both broad spectral coverage and excellent stability. Importantly, 2DFLEX exhibits intrinsic selectivity for stimulated emission, enabling the isolation of excited-state dynamics. This technique represents a significant advancement in fluorescence-detected 2DES and opens new opportunities for elucidating complex electronic processes. 2DFLEX is a spectroscopic technique that integrates excitation-spectrum measurements with time-resolved photoluminescence and has the potential to become a novel standard analytical method for photofunctional materials.