Electronic Structure of Individual Hybrid Colloid Particles Studied by Near-Edge X-ray Absorption Fine Structure (NEXAFS) Spectroscopy in the X-ray Microscope

The electronic structure of individual hybrid particles was studied by nanoscale near-edge X-ray absorption spectromicroscopy. The colloidal particles consist of a solid polystyrene core and a cross-linked poly-N-(isopropylacrylamide) shell with embedded crystalline titanium dioxide (TiO2) nanoparticles (d = 6 +/- 3 nm). The TiO2 particles are generated in the carrier network by a sol-gel process at room temperature. The hybrid particles were imaged with photon energy steps of 0.1 eV in their hydrated environment with a cryo transmission X-ray microscope (T)(M) at the Ti L-2,L-3-edge. By analyzing the image stacks, the obtained near-edge X-ray absorption fine structure (NEXAFS) spectra of our individual hybrid particles show clearly that our synthesis generates TiO2 in the anastase phase. Additionally, our spectromicroscopy method permits the determination of the density distribution of TiO2 in single carrier particles. Therefore, NEXAFS spectroscopy combined with TXM presents a unique method to get in-depth insight into the electronic structure of hybrid materials.