Regensburg 2025 – scientific programme

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DS: Fachverband Dünne Schichten

DS 13: Poster

DS 13.29: Poster

Thursday, March 20, 2025, 18:00–20:00, P1

Investigating Lateral Molecular Heterogeneity with Phase-Resolved Vibrational SFG Microscopy — •ben john, alexander p. fellows, tuhin khan, martin wolf, and martin thämer — Fritz Haber Institute of the Max Planck Society, Berlin, Germany

Understanding molecular heterogeneity at interfaces is crucial for applications in fields such as biophysics and materials science. Systems like lipid rafts in biological membranes or functionalized surfaces in microfluidics require techniques capable of resolving molecular structures, orientations, and compositions with high sensitivity and spatial resolution. Phase-resolved vibrational sum-frequency generation (vSFG) microscopy has emerged as a powerful tool to meet these needs, offering vibrational specificity, orientational sensitivity via second-order selection rules, and sub-micron spatial resolution through frequency upconversion. Despite its potential, traditional vSFG microscopy has faced significant technical challenges in detecting weak signals from monolayers and spatially mapping them. We address these limitations with an advanced phase-resolved vSFG microscope, which achieves improved signal-to-noise ratios and spatial resolution. Using this system, we successfully image phase-separated monolayers of mixed chiral lipids, revealing spatial heterogeneity in molecular orientations and packing structures. This breakthrough positions phase-resolved vSFG microscopy as a transformative approach for characterizing interfacial molecular systems, enabling deeper insights into the complex behaviors of molecular assemblies in both natural and engineered environments.

Keywords: SFG; Microscopy; Phospholipids; Nonlinear Imaging