Regensburg 2025 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 18: Focus Session: Nanoscale Light-matter Interaction I

HL 18.1: Invited Talk

Tuesday, March 18, 2025, 09:30–10:00, H17

Ultrafast Nano-Spectroscopy of Photo-Induced Dynamics in Low-Dimensional Materials — •Takashi Kumagai — Institute for Molecular Science, Okazaki, Japan

Low-dimensional semiconductors have been extensively studied as platforms for fascinating physics and as potential components for quantum nano-devices. Their low dimensionality leads to unique physical properties, driven by strong quantum confinement and reduced dielectric screening. However, this also renders low-dimensional materials highly sensitive to local structures and interactions with their surroundings. To fully understand their superior properties, it is essential to investigate their local structures and how they correlate with photo-induced dynamics. Recently, ultrafast infrared nano-spectroscopy based on scanning near-field optical microscopy (IR-SNOM) has emerged as a powerful tool to directly visualize local structures and dynamics in real time and space at the nanoscale. I will present our latest research to apply ultrafast IR-SNOM to explore nanoscale photo-induced dynamics in low-dimensional materials [1]. In single-layer transition metal dichalcogenides, we have visualized the local many-body dynamics of high-density electron-hole plasma, uncovering the significance of dynamic heterogeneity linked to the non-uniform optoelectronic properties. Furthermore, we have extended ultrafast IR-SNOM to study local exciton dynamics in single-walled carbon nanotubes (SWCNTs). Within individual, isolated SWCNTs, the non-uniform formation of electron-hole pairs is correlated with local strain. [1] Y. Wang, J. Nishida et al. ACS Photonics, accepted.

Keywords: Ultrafast nano-spectroscopy; Infrared SNOM; Low-dimensional material; Transition metal dichalcogenide; Carbon nanotube