Measurement of the conformational switching of azobenzenes from the macro- to attomolar scale in self-assembled 2D and 3D nanostructures.

It is important, but challenging, to measure the (photo)induced switching of molecules in different chemical environments, from solution through thin layers to solid bulk crystals. We compare the cis-trans conformational switching of commercial azobenzene molecules in different liquid and solid environments: polar solutions, liquid polymers, 2D nanostructures and 3D crystals. We achieve this goal by using complementary techniques: optical absorption spectroscopy, femtosecond transient absorption spectroscopy, Kelvin probe force microscopy and reflectance spectroscopy, supported by density functional theory calculations.

Stoichiometric BiSe topological insulator ultra-thin films obtained through a new fabrication process for optoelectronic applications.

A new fabrication process is developed for growing BiSe topological insulators in the form of nanowires/nanobelts and ultra-thin films. It consists of two consecutive procedures: first BiSe nanowires/nanobelts are deposited by standard catalyst free vapour-solid deposition on different substrates positioned inside a quartz tube. Then, the BiSe, stuck on the inner surface of the quartz tube, is re-evaporated and deposited in the form of ultra-thin films on new substrates at a temperature below 100 °C, which is of relevance for flexible electronic applications.

The incorporation site of Er in nanosized CaF.

The incorporation site of Er dopants inserted at high and low concentration (respectively 5 and 0.5 mol%) in nanoparticles of CaF is studied by x-ray absorption spectroscopy (XAS) at the Er L edge. The experimental data are compared with the results of structural modeling based on density functional theory (DFT).