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O: Fachverband Oberflächenphysik

O 61: Organic molecules on inorganic substrates: electronic, optical and other properties II

O 61.3: Vortrag

Mittwoch, 11. März 2026, 15:30–15:45, HSZ/0201

Azimuthal-Scanning SFG Microscopy for Mapping Packing Motifs and In-Plane Disorder in Molecular Films — •Nasim Mirzajani, Ben John, Alex Fellows, and Martin Thaemer — Fritz-Haber-Institut, Berlin, Germany

Phase-resolved vibrational sum-frequency generation (SFG) microscopy is a powerful tool for probing anisotropic and heterogeneous structure of molecular films. As a second order nonlinear technique, SFG is uniquely sensitive to disorder in film morphology but it has not been yet used to quantify order in molecular film assemblies. Here, we introduce an azimuthal-scanning SFG microscopy approach that extracts detailed information on structure as well as in-plane orientational order by analyzing the full set of rotational frequencies arising from azimuthal dependence. Applying the method to a lipid monolayer, we determine the full 3D structure of the lipids, the packing motif as well as the degree of its in-plane disorder. This technique provides a general framework for probing packing structure in thin films and is broadly applicable to diverse molecular and phononic materials.

Keywords: sum frequency generation; microscopy; molecular films; order; heterogeneity