Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 27: Plasmonics and nanooptics: Light-matter interaction, spectroscopy – Poster

O 27.4: Poster

Monday, March 9, 2026, 18:00–20:00, P2

Tunable Stokes-shifted photoluminescence and defect emission from hBN excited with a supercontinuum laser — •Prabhdeep Singh, Bharti Garg, Maximilian Black, Masoud Taleb, and Nahid Talebi — Institute of Experimental and Applied Physics, Kiel University, Kiel, Germany

We investigate the photoluminescence (PL) of hexagonal boron nitride (hBN) flakes placed on holey carbon grids under tunable supercontinuum excitation from 460 to 650 nm. The spectra consistently show a fixed defect emission around 537 nm together with a stokes-shifted peak that moves linearly with the excitation wavelength. The excitation emission energy differences cluster around 0.17 eV and 0.20 eV, matching the in-plane E_1u and E_2g phonon modes of hBN. Cathodoluminescence measurements on the same flakes exhibit only the defect line, along with phonon sidebands. On a gold substrate, we additionally observe a weak third moving peak at the sum of the two phonon energies, arising from surface enhanced Raman spectroscopy scattering (SERS). Spatial PL maps, intensity variations, and measurements with different optical density filters further allow us to evaluate the local emission characteristics and estimate the down-conversion efficiency. The results provide a consistent picture of phonon-mediated optical processes in hBN. Using tunable supercontinuum excitation, we reveal phonon-assisted stokes emission in hBN and a SERS phonon-combination peak on gold an excitation scheme not previously explored for Raman-type processes in this material.

Keywords: hexagonal boron nitride (hBN); phonon-assisted emission; defect photoluminescence; Stokes shift; supercontinuum excitation