Three-dimensional optical trapping and orientation of microparticles for coherent X-ray diffraction imaging

Obtaining a fundamental understanding of crystal growth and chemical reactions in solution is of broad and enduring interest for materials discovery, structural biology, and catalysis. The recent availability of bright, coherent X-ray sources can enable these fluctuation-driven processes to be monitored in situ through the technique of coherent X-ray diffractive imaging (CXDI), in which the 3D internal structure of microscopic objects is determined with nanometer resolution from the fine structure of diffraction peaks. So far, Bragg CXDI has required immobilization of particles on a substrate, which modifies their structure and chemical activity. Here, we demonstrate Bragg CXDI on a single particle that is trapped and oriented in solution using optical tweezers and thus obtain its 3D structure and strain map.