Advanced characterization of molecular nanostructures and interfaces with resonant X-ray scattering*

Emergent properties within molecular materials are determined by their nanoscale ordering, in particular at interfaces. This has revealed a potential for their use in drug delivery, printable electronics, and bottom-up nano-assembly if their ordering can be controlled. A major roadblock is the lack of nanoprobes that can precisely characterize ordering within these delicate materials that contain light elements, 3D structures, and low crystallinity. I will discuss recent progress in developing a new class of measurements based on X-rays resonant with molecular transitions to enable quantitative characterization of molecular order. Resonant soft X-ray scattering (RSoXS) combines polarized spectroscopy with scattering, enabling sensitivity to bond type and orientation – similar to ellipsometry and RAMAN spectroscopy but with higher spatial resolution. Contrast variation can be achieved by tuning the photon energy – similar to deuteration in neutron scattering but without the need of laborious and disruptive chemical labelling. I will highlight our recent progress in developing quantitative RSoXS analyses for characterizing molecular interfaces as well as ordering within and between nanostructures. In particular, the ability of polarized RSoXS to measure local molecular orientation even in polydisperse 3D matrices is not possible with any other technique. I will also touch on our work in developing a new instrument to measure structural evolution of solvated nanoparticles and operando electrochemical processes. As RSoXS continues to mature, it will enable increased understanding and control of molecular and hybrid nanostructures resulting in revolutionary new technologies based on these novel materials.