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Updated: May 21, 2026

Polarization-Sensitive Two-Photon Microscopy for a Label-Free Amyloid Structural Characterization
Published on: September 8, 2023
Line narrowing of excited-state transitions in nonlinear polarization spectroscopy: application to water-soluble
Mario Schoth1, Marten Richter, Andreas Knorr
1Institut für Theoretische Physik, Technische Universität Berlin, Berlin, Germany. schoth@itp.tu-berlin.de
Abstract:
The homogeneous linewidth of dye aggregates like photosynthetic light-harvesting complexes contains important information about energy transfer and relaxation times that is, however, masked by inhomogeneous broadening caused by static disorder. Whereas there exist line narrowing techniques for the study of low-energy exciton states, the homogeneous linewidth of the high-energy states is not so easy to decipher. Here we present a microscopic theory for nonlinear polarization spectroscopy in the frequency domain that contains a dynamic aggregate selection revealing the homogeneous linewidth of these states. The theory is applied to the water-soluble chlorophyll-binding protein for which the high-energy exciton state was predicted to exhibit a sub-100-fs lifetime.
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