Measurement of buried molecular interfaces enabled by resonant X-ray scattering analysis
We demonstrate a new quantitative X-ray scattering analysis that probes 3D molecular nanostructures and even buried interfaces between those structures. These organic nanomaterials are of increasing impact in bottom-up assembly, electronic devices, and biomimetic applications, but their internal structure is difficult to probe due to light elements and no or low crystallinity. For example, only planar interfaces were previously accessible with laborious and disruptive chemical tagging. This new technique eliminates the need for tagging and can investigate nonplanar interfaces more commonly found in nature. The technique is a leap in X-ray science because the analysis requires absolute scattering intensity at an absorption edge where low sample penetration depths preclude the use of calibration standards. Each molecule has a unique fingerprint encoded as a function of photon energy, which the technique uses to chemically separate components of the nanostructure. Through our new spectral analysis, complex molecular structures composed of any number of unique molecular species can now be fully analyzed.