Understanding the chemical and physical properties of surfaces at the molecular level is highly relevant in the fields of medicine, semiconductors, batteries, etc. where precise atomic level control of determines materials and device performance. In particular, molecular order and domains affect many of the desired functional properties with carrier transport, wettability, and chemical reactivity often controlled by intermolecular coupling. However, both imaging of molecular surfaces and spectroscopy of molecular coupling has long been challenged by limited chemically specific contrast, spatial resolution, sensitivity, and precision. In this work, a team of STROBE researchers demonstrate vibrational excitons as a molecular ruler of intermolecular coupling and quantum sensor for wave function delocalization to image nanodomain formation in self-assembled monolayers. In novel precision spatio-spectral infrared scattering scanning near-field optical microscopy combined with theoretical modelling few nanometer domain sizes and their distribution across micron scale fields of view could be resolved. This approach of vibrational exciton nanoimaging is generally applicable to study structural phases and domains in a wide range of molecular interfaces and the method can be used for engineering better molecular interfaces, with controlled properties for molecular electronic, photonic, or biomedical applications.
