21–23 Sept 2023
Central European University, CEU Nador 15 Campus (Budapest, Hungary)
Europe/Budapest timezone

Structural characterization and reversible laser-assisted modification of chalcogenide photonic media

22 Sept 2023, 11:40
30m
room 103 (Central European University, CEU Nador 15 Campus (Budapest, Hungary))

room 103

Central European University, CEU Nador 15 Campus (Budapest, Hungary)

H-1051 Budapest, Nádor utca 9. (Hungary)
Fr2

Speaker

Roman Holomb (Wigner Research Centre for Physics, Hungary)

Description

The super-bandgap laser irradiation of the in situ prepared As-S chalcogenide films was found to cause drastic structural transformations and unexpected selective diffusion processes, leading to As enrichment on the nanolayer surface. Excitation energy dependent synchrotron radiation photoelectron spectroscopy showed complete reversibility of the molecular transformations and selective laser-driven mass transport during "laser irradiation"-"thermal annealing" cycles. Molecular modeling and density functional theory calculations performed on As-rich cage-like nonoclusters built from basic As1S3, As2S2 and As3S1 structural units indicate that the underlying microscopic mechanism of laser induced transformations is connected with the realgar-pararealgar transition in the As-S structure. The detected changes in surface composition as well as the related local and molecular structural transformations are analyzed and a model is proposed and discussed in detail. It is suggested that the formation of a concentration gradient is a result of bond cleavage and molecular reorientation during transformations and anisotropic molecular diffusion.

Primary author

Roman Holomb (Wigner Research Centre for Physics, Hungary)

Co-author

Miklós Veres (Wigner Research Centre for Physics)

Presentation materials

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