2024-10-10 (Czwartek)
Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 10:15  Calendar icon
Katarzyna Krajewska (IFT UW)

Strong- versus ultra-strong-field physics

When increasing the intensity of optical pulses we can probe different regimes of laser-matter interactions. Specifically, in the area of strong-field physics we deal with bound electrons that undergo various atomic transformations due to the interaction with the laserfield. The theoretical framework behind is non-relativistic quantum mechanics, based on the time-dependent Schrodinger equation. Going toward higher intensities, we reach the ultra-strong-field regime. Here,we deal with free electrons whose quiver energy in a laser field becomes comparable to their rest mass energy. Thus, we enter the area governed by relativistic quantum mechanics, that is based on the Dirac equation. The physics in those two regimes has to be treated using different theoretical methods and inherently different physical effects should be observed there. But is it always the case? In my talk, I will address this question considering two seemingly different physical processes, representing each of those regimes: ionization and electron-positron pair creation.
2024-10-03 (Czwartek)
Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 10:15  Calendar icon
Bartosz Krajnik (Politechnika Wrocławska)

Fluorescence Microscopy of Single Nanostructures: From Imaging to Molecular Dynamics

Single-molecule microscopy and spectroscopy are advanced research techniques that enable the real-time tracking and analysis of individual molecules. These methods provide detailed insights into molecular dynamics, interactions, and structures, which cannot be achieved by studying phenomena at the ensemble level. Two techniques in this field, SOFI (Stochastic Optical Fluctuation Imaging) and defocused wide-field fluorescence microscopy, offer unique approaches for high-resolution molecular/nanoparticle analysis. SOFI is based on the statistical analysis of fluorescence signal fluctuations generated by single emitters. This allows for image reconstruction with a resolution beyond the diffraction limit of light, particularly for densely labeled samples. Defocused wide-field fluorescence microscopy involves imaging under deliberately defocused conditions. The emerging single-molecule patterns provide information about the orientation and structure of individual molecules. This technique is particularly suitable for studying rotational dynamics (e.g., molecular motors), allowing for the direct observation of even tens of individual molecules. Both methods are powerful tools in modern molecular research, providing extensive possibilities for analyzing structures and processes at the nanoscale level.