Exploring 2D Materials with Synchrotron Infrared-to-Terahertz Nanospectroscopy

Many fundamental excitations of 2D materials have resonance energies of a few 10 to 100 meV, i.e., in the infrared and terahertz (THz) frequency range. Infrared nanospectroscopy provides direct access to these excitations with a spatial resolution of ~10 nm. At the National Synchrotron Light Source II (NSLS-II), we established a new nanospectroscopy setup, which uniquely covers the ultrabroad frequency range from 5-242 THz (175-8000 cm^‑1, 22-1000 meV). We highlight various results obtained with this setup, such as terahertz polariton interferometry of the van der Waals material GeS [1], graphene cavity plasmonics [2], and negative polaritonic refraction in an hBN-MoO₃ hetero-bicrystal [3]. Also, we will discuss the novel opportunities of performing infrared nanospectroscopy in high magnetic fields (≤7 T) [4,5].



The infrared nanospectroscopy setup at the 22IR2/MET beamline of NSLS-II is available for general use. Application for beamtime: https://www.bnl.gov/nsls2/userguide/



[1] L. Wehmeier et al., ACS Photonics 10, 4329 (2023).

[2] R. A. Vitalone et al., ACS Nano (2024).

[3] L. Wehmeier, S.-J. Yu et al., Adv. Mater. 36, 2401349 (2024).

[4] M. Dapolito et al., Nat. Nanotechnol. 18, 1409 (2023).

[5] L. Wehmeier et al., Sci. Adv. 10, eadp3487 (2024).