Infrared and Terahertz Nanospectroscopy of 2D Materials at the National Synchrotron Light Source II

2D materials provide unprecedented opportunities for tailoring material properties, e.g., via exfoliation, stacking of heterostructures, and twisting. Many fundamental material excitations of 2D materials are found at energies of a few 10 meV to a few 100 meV, i.e., in the infrared and terahertz (THz) frequency range. Infrared nanospectroscopy provides direct access to these excitations at a spatial resolution of ~10 nm. At the National Synchrotron Light Source II, we have established a new infrared-to-THz nanospectroscopy setup, which uniquely enables spectroscopy in the ultrabroad frequency range from 5-242 THz (175-8000 cm^‑1, 22-1000 meV, ~1-57 µm). To demonstrate our system’s capabilities for THz nanospectroscopy, we showcase ultrabroadband synchrotron nanospectroscopy of phonons in ZnSe (~7.8 THz) and BaF₂ (~6.7 THz), as well as polariton interferometry of hyperbolic phonon polaritons in the van der Waals material GeS (6-8 THz).

The NSLS-II near-field nanospectroscopy setup at the 22IR2/MET infrared beamline is open for general user beamtime proposals. See: https://www.bnl.gov/nsls2/userguide/