Abstract

Following our investigation of intercalated bilayer graphene [1], we show how intercalation can be used to decouple h-BN from a Ni(111) substrate, yielding a quasi-free-standing layer. Using helium atom scattering, we assess energy dissipation through the electron–phonon coupling parameter λ and reveal how decoupling from the substrate modifies this coupling. We then turn to molecular dynamics in weakly interacting systems, where friction is low and motion is typically too fast to access by real-space methods [2]. Using helium spin-echo (HeSE) spectroscopy, we identify clear differences in the nanoscale motion of both benzene and water on h-BN-based interfaces compared with graphene: benzene on h-BN/Ni exhibits a higher diffusion barrier than on graphene/Ni, while water shows lower activation energies and stronger rotational–translational coupling on h-BN/Ni than on graphene/Ni [3]. Together, these results highlight how subtle differences in surface bonding and substrate coupling govern mobility and energy dissipation on 2D materials. More broadly, we highlight recent advances showing that HeSE can provide quantitative access to the intrinsic lifetimes of low-energy surface phonons at finite wavevectors, as demonstrated for the Rayleigh mode on Ag(001), thereby opening a direct route to vibrational energy dissipation at surfaces.

[1] How does intercalation affect the structure and dynamics of bilayer graphene? Carbon 238, 120156 (2025). [2] Nanoscale Motion of Organic π-Conjugated Molecules: Exploring van der Waals Forces, Friction, and Quantum Effects. Nanoscale Horiz. 10, 3158 (2025). [3] Understanding water behaviour on 2D material interfaces through single-molecule motion on h-BN and graphene Nat. commun. 16, 10465 (2025).