Physico-Chemical nanomaterials science 

Laser-stimulated reversible structural modification of surface As-enriched As-S nanolayers 

Kondrat O.B.1, Holomb R.M.1,2, Mitsa V.M.1, Tsud N.3, Vondráček M.4, Mitsa O.V.1, Matolin V.3, Veres M.2
1 Information Control Systems and Technologies Department, Uzhhorod National University. 88000 Uzhhorod, Ukraine. 
E-mail: oleksandr.kondrat@uzhnu.edu.ua
2 Wigner Research Centre for Physics, Hungarian Academy of Sciences, 1121 Budapest, Hungary.
3 Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague, Czech Republic.
4 Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, 182 21 Prague, Czech Republic.

The As45S55 nanolayers were prepared in-situ in preparation chamber of Materials Science Beamline (MSB, Elettra–Sincrotrone Trieste) by thermal evaporation of bulk glass powder and deposition onto a silicon substrate. The atomic composition, local structure, and their characteristics, as well as reversible structural changes during thermal annealing and laser illumination by monochromatic coherent light with over band-gap photon energy of in-situ fabricated As45S55 nanolayers were examined by synchrotron radiation photoelectron spectroscopy [1]. It was established that the structure of as-deposited sample is slightly enriched by As. In situ thermal annealing rearranges the structure of As-S film and leads to the formation As-S3 and As-Se2As s.u. following by dissociation of s.u. with As-As bonds. From the other hands, in situ over band-gap laser illumination increases the contribution of As-S2As s.u. in the structure of As-Se nanolayers even more then in the as-deposited film. The "thermal annealing" - "laser illumination" of As-S nanolayers performed in cycle mode reveals the reversibility of the structural changes.

1.	Holomb R., Kondrat O., Mitsa V., Mitsa A., et al. Gold nanoparticle assisted synthesis and characterization of As-S crystallites: scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray and Raman spectroscopy combined with DFT calculations. Journal of Alloys and Compounds 894 (2021) 162467