Seminarium Optyczne

Short wavelength radiation with a wavelength of 10nm to 120nm is called Extreme ultraviolet (EUV) radiation. Radiation with an even shorter wavelength, i.e. 0.1-10nm, is called soft X-ray (SXR). EUV and SXR radiation is very strongly absorbed in matter in the surface, in a layer of about 100-500 nm thick, which allows the to study the properties of these materials using the near edge X-ray absorption fine structure, e.g. for determining chemical composition by NEXAFS spectroscopy [1-4] or atomic structure using EXAFS [5]. In addition due to possible large spectral bandwidth and small coherence length, it allows to record the interference between the beams reflected from the planar discontinuities of index of refraction in the soft X-ray range from nanometer periodic structures and record it as a modifies reflection spectrum. From that spectrum the depth profile of nanometer planar structures can be reconstructed in a spectral-domain optical coherence tomography scheme to study such multilayer structures with nanometer axial resolution and in a noninvasive way [6]. These properties of EUV and SXR radiation will be discussed during the presentation and supported by experiments, performed using compact laser-plasma source, illustrating the issues presented. The research was based on a compact, laser-plasma EUV and SXR radiation source with a double stream gas puff target, developed at the Military University of Technology. This source has been used in recent years for the research work of the Laser-Matter Interaction Team at the Institute of Optoelectronics, Military University of Technology, Poland. 1. “Compact system for near edge X-ray fine structure (NEXAFS) spectroscopy using a laser-plasma light source”, P. Wachulak, M. Duda, A. Bartnik, A. Sarzyński, Ł. Węgrzyński, M Nowak, A. Jancarek, H. Fiedorowicz, Optics Express 26, 7, 8260-8274 (2018), DOI: 10.1364/OE.26.008260 “Single-Shot near Edge X-ray Fine Structure (NEXAFS) Spectroscopy Using a Laboratory Laser-Plasma Light Source”, P. Wachulak, M. Duda, T. Fok, A. Bartnik, Z. Wang, Q. Huang, A. Sarzyński, A. Jancarek, and H. Fiedorowicz, Materials 11, 8, 1303 (2018), doi: 10.3390/ma11081303 “2-D elemental mapping of an EUV-irradiated PET with a compact NEXAFS spectromicroscopy”, P. Wachulak, M. Duda, A. Bartnik, A. Sarzyński, Ł. Węgrzyński, H. Fiedorowicz, Spectrochimica Acta Part B: Atomic Spectroscopy 145, 107-114 (2018), https://doi.org/10.1016/j.sab.2018.04.014 „NEXAFS at nitrogen K-edge and titanium L-edge using a laser-plasma soft x-ray source based on a double-stream gas puff target”, P. Wachulak, M. Duda, A. Bartnik, Ł. Węgrzyński, T. Fok, H. Fiedorowicz, APL Photonics 4, 030807 (2019); https://doi.org/10.1063/1.5085810 “EXAFS of titanium LIII edge using a compact laboratory system based on a laser-plasma soft X-ray source”, P. Wachulak, T. Fok, A. Bartnik, K. A. Janulewicz, H. Fiedorowicz, Applied Physics B 126, 11 (2020), https://doi.org/10.1007/s00340-019-7365-y “Optical coherence tomography (OCT) with 2 nm axial resolution using a compact laser plasma soft X-ray source”, P. Wachulak, A. Bartnik, H. Fiedorowicz, Scientific Reports 8, 8494 (2018), DOI:10.1038/s41598-018-26909-0, https://rdcu.be/QZQP