Hydride Formation in Single Palladium and Magnesium Nanoparticles Studied By Nanoplasmonic Dark-Field Scattering Spectroscopy

Nanosystems can exhibit interesting novel chemical and physical properties and are widely exploited for their functionalities. [ 1–6 ] Scrutinizing such systems and relating, e.g., details in their chemistry and geometry to functionality, remains, however, a signifi cant experimental challenge. Unwanted artifacts and averaged responses are always present in ensembles of a sample material and are mainly caused by inhomogeneous size distributions and differences in the local chemistry and the local structure of (quasi-identical) nanoentities in the ensemble. Experiments aiming at the characterization of single functional nanoentities have the potential to completely eliminate such problems, which facilitates highly relevant systematic studies of correlations between details in nanoentity geometrical, physical and chemical properties, and functionality. In applications such as catalysis or other areas of gas–solid or liquid–solid interactions as well as in solid-state reactions issues including temperature or mass-transport gradients present in powder samples, which often have to be stabilized by surfactants or similar, can cause signifi cant problems in data interpretation and quantifi cation by causing false apparent kinetics, “smeared out” phase transitions, etc. The same problems are also signifi cant in situations when statistical averaging over even (potentially) identical particles may hide interesting phenomena such as oscillatory kinetics. [ 7 ] In general, such effects make it very diffi cult or even impossible to correlate details in the local structure, size, and chemical composition of the probed nanomaterials with their functionality, e.g., kinetics, phase transitions, thermodynamics, catalytic activity, etc., when ensemble samples are used. In the fi eld of nanoplasmonic sensing, the introduction of dark-fi eld scattering spectroscopy (DFSS) has made it possible to study the optical properties of single nanoparticles and to study effects of particle size and particle shape [ 8 ] as well as the refractive index of the surrounding medium [ 9 ] on the localized surface plasmon resonance (LSPR) in single Au and Ag nanoparticles. It has also been shown that it is feasible to directly