Near-field infrared microscopy of low-dimensional systems

Nyomtatóbarát változatNyomtatóbarát változat
Doctoral school: 
Fizikai Tudományok Doktori Iskola
Pekker Áron
Wigner Research Centre for Physics (WIGNER FK)
Job title: 
Senior Research Scientist
Academic degree: 
Sándor Bordács
Department of Physics
Job title: 
Assistant Professor
Academic degree: 

The spatial resolution of classical far-field spectroscopy is constrained by the so-called diffraction limit. For the workaround of this problem we need to change the measurement configuration. Near surfaces we can create electromagnetic fields containing components with much finer spatial information than their propagating counterparts. However, these fields decay quickly away from the surface. With the use of an optical antenna in close proximity to the surface these evanescent fields can be converted to propagating ones and detected with conventional instruments. This is the working principle of the scattering type near-field microscope, a novel optical characterization tool capable of nanometer resolution regardless of the used wavelength.

The instrument in our laboratory is a combination of an atomic force microscope (AFM) and infrared lasers. The laser is focused on the metallic AFM tip and by scanning the tip over the sample we can measure the optical response of the sample with nanometer scale resolution. The optical signal and the sample topography are measured simultaneously, thus the correlation of sample features with the optical response is straightforward. Our infrared lasers work in the mid-infrared range where ligt can interact with molecular vibrations, phonons, free electrons, and other collective excitations like surface plasmon polaritons.

Our group works mainly with various low-dimensional materials like hexagonal boron nitride, graphene, carbon nanotubes and boron nitride nanotubes . These materials can be modified with chemical or physical methods. We can fill the inner cavity of the nanotubes with different small molecules or modify the surface of the two-dimensional materials. These modifications can be followed and analyzed with the help of the near-field infrared microscope. Recently we expanded our field of interest to biological samples with few nanometers in size like extracellular vesicules.

The task of the applicant is to carry out near-field infrared measurements on the aforementioned systems, explain their optical response by the use of theoretical models and contribute to the development and modification of the experimental setup.

English language proficiency for reading scientific articles. Interest in experimental work. Optics and solid state physics background.