Electronic and structural fingerprints of charge density wave excitations in extreme ultraviolet transient absorption spectroscopy

2022/11/07 by Tobias Heinrich, Heinrich, Tobias, Hung-Tzu Chang +9 · 3 citations
Engineering · Materials Science · #Chalcogenide Semiconductor Thin Films #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Molecular Junctions and Nanostructures #Optics (physics.optics) #Organic and Molecular Conductors Research

paper · pdf · doi:10.48550/arxiv.2211.03562

openalex publication_date 2022/11/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Femtosecond core-level transient absorption spectroscopy is utilized to investigate photoinduced dynamics of the charge density wave in 1T-TiSe2 at the Ti M2,3 edge (30-50 eV). Photoexcited carriers and phonons are found to primarily induce spectral red-shifts of core-level excitations, and a carrier relaxation time and phonon heating time of approximately 360 fs and 1.0 ps are extracted, respectively. Pronounced oscillations in delay-dependent absorption spectra are assigned to coherent excitations of the optical A_1g phonon (6.0 THz) and the A_1g^* charge density wave amplitude mode (3.3 THz). By comparing the measured spectra with time-dependent density functional theory simulations, we determine the directions of the momentary atomic displacements of both coherent modes and estimate their amplitudes. This work presents a first look on charge density wave excitations with table-top core-level transient absorption spectroscopy, enabling simultaneous access to electronic and lattice excitation and relaxation.

Cited by

• Excitons and Optical Response in Excitonic Insulator Candidate TiSe₂
• Long-lived dynamics of the charge density wave in TiSe2 observed by time-resolved neutron diffraction
• Electron-phonon-dominated charge-density-wave fluctuations in TiSe₂ accessed by ultrafast nonequilibrium dynamics

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