Bonn 2025 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 24: Poster – Interaction with VUV and X-ray light
A 24.6: Poster
Mittwoch, 12. März 2025, 17:00–19:00, Tent
Probing few femtosecond dynamics in thin solids using a table top extreme ultraviolet transient absorption spectroscopy — •Monalisa Mallick1, Tobias Helk1, Zichen Xie1, Rudrakant Sollapur1, Michael Zürch1,2, and Christian Spielmann1 — 1Institute of Optics and Quantum Electronics, Friedrich Schiller University, 07743 Jena, Germany — 2Department of Chemistry, University of California, Berkeley, 94720, USA
In 2D materials like transition metal dichalcogenides and thin metallic films, nanoscale dimensions strongly affect the processes like carrier and phonon relaxation and scattering timescale. We are developing an extreme ultraviolet (XUV) spectroscopy system which offers element and site-specific sensitivity and high temporal resolution. It employs a pump-probe scheme, where samples are excited by few-cycle near-infrared (NIR) pulses and probed with broadband XUV pulses. Transient absorption changes near the absorption edges of metals or chalcogens are recorded to reveal the underlying few femtosecond-scale dynamics.To generate few-cycle pulses, 40 fs, 800 nm pulses from a commercial Ti:Sapphire laser are compressed using a neon-filled hollow-core fiber (HCF).The dispersion is compensated using dielectric chirped mirrors, achieving pulse durations as short as ~5 fs. These pulses enable broadband XUV generation via high harmonic generation (HHG) in argon gas, producing radiation spanning 30-100 eV. By employing a recirculating HHG gas, and active beam pointing stabilization at the fiber entrance, the system demonstrates stability for over 12 hours.
Keywords: broadband extreme ultraviolet; transient absorption spectroscopy; high harmonic generation; transition metal dichalcogenides; femtosecond