Donor–Acceptor Recombination Emission in Hydrogen-Terminated Nanodiamond

Fluorescence spectra of nanodiamonds synthesized at high pressure from adamantane and other organic compounds show narrow (≈1 nm) lines of unknown origin over the spectroscopic range from ≈500 to 800 nm. The study proposes and experimentally confirms the hypothesis that these lines are related to radiative recombination of donor–acceptor pairs (DAP). According to the experimental data, these pairs can be formed from donor-like substitutional nitrogen present in the diamond lattice and 2D acceptor layer resulting from the effect of transfer doping on the nanodiamond surface. A peculiar behavior of the narrow lines is identified within the temperature range of 100–10 K: their energy position slightly shifts downward, and the majority of the lines divide into two or more components as the temperature decreases. The lines are shown to be predominantly associated with single photon emitters, with an emission rate exceeding 1 million counts s⁻¹ at room temperature. A new narrowband source of room-temperature fluorescence found in hydrogen-terminated nanodiamonds push horizons for quantum optical technologies related to the development of single photon emitters and temperature nanosensors.