Towards the Optical Control of Resonantly Bonded Materials: An Ultrafast X-Ray Study

This thesis highlights advancements in time-domain methodologies using ultrafast pulses from X-ray free-electron lasers to probe the interactions between electrons and phonons in photoexcited materials. It demonstrates the reconstruction of the nonequilibrium lattice structure and identification of a novel lattice instability in SnSe. The study of excited-state phonon dispersion in SnSe provides insight into how photoexcitation alters the strength of specific bonds. Additionally, quantitative measurements of electron-phonon coupling in Bi2Te3 and Bi2Se3 highlight the importance of time-resolved X-ray scattering techniques in understanding the interplay between electron orbitals, atomic bonds, and structural instabilities.

Format: Hardback
Length: 159 pages
Publication date: 23 January 2024
Publisher: Springer International Publishing AG

This thesis delves into fundamental insights into materials structure and dynamics, focusing on a microscopic perspective. It showcases significant advancements in time-domain methodologies utilizing ultrafast pulses from X-ray free-electron lasers (FELs) to explore the intricate interactions between electrons and phonons in photoexcited materials. Through femtosecond time-resolved X-ray diffraction, the author quantifies the coherent atomic motion trajectory upon sudden excitation of carriers in SnSe, enabling the reconstruction of the nonequilibrium lattice structure and the identification of a novel lattice instability towards a higher-symmetry structure. This research is followed by an in-depth investigation of the excited-state phonon dispersion in SnSe using time-resolved X-ray diffuse scattering, providing valuable insights into how photoexcitation modifies the strength of specific bonds, ultimately leading to the observed lattice instability in X-ray diffraction. Furthermore, by combining ultrafast X-ray diffraction and ARPES, the author conducts quantitative measurements of electron-phonon coupling in Bi2Te3 and Bi2Se3, highlighting the significance of time-resolved X-ray scattering techniques based on FELs in unveiling the intricate details of interplay between electron orbitals, atomic bonds, and structural instabilities. The microscopic information obtained from these methods empowers the rationalization of materials control and functional property design, paving the way for innovative advancements in various fields.

Weight: 430g
Dimension: 235 x 155 (mm)
ISBN-13: 9783031428258
Edition number: 1st ed. 2023