2026/02/25 by Ramon Cuscó, Thomas Poirier, James H. Edgar · 1 voice
Materials Science · #2D Materials and Applications #Boron and Carbon Nanomaterials Research #Graphene research and applications
paper · doi:10.1103/yq1x-tt5p
openalex created_date 2026/02/25 · openalex publication_date 2026/02/25 · openalex updated_date 2026/07/23
We have measured second-order Raman scattering in high-quality monoisotopic ℎ-BN crystals for all possible boron and nitrogen isotope combinations. The second-order spectra are dominated by phonon combinations and are well aligned with density-functional perturbation-theory calculations of the two-phonon density of states. The isotopic shifts are well described by second-order perturbation of the dynamical matrix. The analysis of the Raman spectra of the monoisotopic samples and their isotopic shifts allows us to unambiguously assign the second-order peaks and to determine phonon frequencies at 𝑀 and 𝐾 zone-edge points, as well as on the 𝑇 line. This study demonstrates the usefulness of Raman spectroscopy as a tool for probing the frequencies of zone-edge phonons. These play a prominent role in the phonon-assisted emission in ℎ-BN. The study also serves as a stringent test of the density-functional theory calculations commonly used to estimate these frequencies.