Sanjoy Kr Mahatha

Abstract Interfaces between molecules and 2D materials exhibit energy-driven functionalities, wherein charge transfer directs molecular motion. Unlike equilibrium systems, where molecular assemblies settle into static configurations, continuous energy input can drive transient, collective molecular rearrangements. Here, we reveal ultrafast spectroscopic fingerprints of a collective rotational response of molecules on a 2D material following photoexcitation.

Tin (Sn) thin films are deposited on Bi 2 $_2$ Se 3 $_3$ substrate via vapor deposition under ultrahigh vacuum conditions, and the surface electronic structure and interface chemistry are systematically investigated using X-ray and ultraviolet photoemission spectroscopy (XPS and UPS) measurements. Spectroscopy analysis reveals the formation of SnSe bonds along with a reduction of Bi, leading to the emergence of multiple Sn-based interfacial phases such as SnSe and SnSe 2 $_2$ .

We combine ab initio calculations based on many-body perturbation theory and the cumulant expansion with angle-resolved photoemission spectroscopy (ARPES) to quantify the electron-plasmon interaction in the highly doped semiconducting transition metal dichalcogenide 1T−HfS2. ARPES reveals the emergence of satellite spectral features in the vicinity of quasiparticle excitations at the bottom of the conduction band, suggesting coupling to bosonic excitations with a characteristic energy of 200 meV.