Encapsulation of molecules in nanotubes: Carbon and boron nitride nanotubes contain a special form of cavity, a few nanometers wide and often up to a micrometer long. These cavities naturally present themselves as containers that can be filled with molecular-sized species. The interaction between the guest molecules and the host nanotubes can alter the properties of both, and lead to new, interesting characteristics. As both carbon and boron nitride nanotubes possess a remarkable chemical and thermal stability, they are also suitable templates to facilitate the synthesis of 1D nanostructures, such as graphene nanoribbons within their cavity. Our research focuses on the development and optimization of various encapsulation methods, and spectroscopic characterization of the properties of the synthesized novel nanostructures.

Organic-inorganic halide perovskites are promising candidates for photovoltaic and optoelectronic applications owing to their compositional flexibility, solution processability and easy adaptability to scale up production methods. The band gap of perovskites can be easily tuned in a wide range via appropriately mixed halide compositions and/or addition of larger spacer cations that break up the perovskite structure to layers, creating so-called 2D perovskites. The main challenge that currently hinders the wide-range application of perovskites is the inherent instability of most mixed halide compositions and their instability upon exposure to environmental stressors, such as humidity, oxygen, light and heat. Our research focuses on understanding these phase segregation and degradation processes using optical spectroscopy techniques. Measurements can be performed within the glove box or in an in-house developed environmental cell that allows us to measure the samples in a controlled environment and in a wide temperature range.

Szöveg

Optical techniques that use diffractive optics suffer from a resolution limit depending on the wavelength of the light wave involved in the measurements. This so-called diffraction limit comes the most crucial at infrared wavelengths where the wavelength of the applied light reaches several micrometers. This limitation makes the study of the low energy properties of individual nanostructures almost impossible.

Scanning near-field optical microscopy is an emerging optical method to overcome the diffraction limit with achieving wavelength-independent resolution down to 10 nm. The method is based on atomic force microscopy (AFM). The optical near-fields are created by the side-illumination of a metal-coated (usually) AFM tip. The near-fields that are located at the apex of the tip are used to locally probe the sample. Additionally to the nanoscale resolution, optical near-fields can be utilized to launch highly confined polaritons in low dimensional materials.

Our research uses SNOM for different projects from nanoscale analytics to polariton physics.