Photoluminescence of single colour defects in 50 nm diamond nanocrystals

TL;DR

This study investigates the optical properties of 50 nm diamond nanocrystals containing stable nitrogen-vacancy defects, highlighting their potential as long-lasting, biocompatible fluorescent probes for biological applications.

Contribution

The paper demonstrates the presence of stable NV0 defects in 50 nm diamond nanocrystals and characterizes their photoluminescence properties at room temperature.

Findings

Stable NV0 defects observed in nanocrystals.

Photoluminescence spectrum shows zero-phonon line at 575 nm.

Nanocrystals are promising for bio-compatible fluorescent probes.

Abstract

We used optical confocal microscopy to study optical properties of diamond 50 nm nanocrystals first irradiated with an electron beam, then dispersed as a colloidal solution and finally deposited on a silica slide. At room temperature, under CW laser excitation at a wavelength of 514.5 nm we observed perfectly photostable single Nitrogen-Vacancy (NV) colour defects embedded in the nanocrystals. From the zero-phonon line around 575 nm in the spectrum of emitted light, we infer a neutral NV0 type of defect. Such nanoparticle with intrinsic fluorescence are highly promising for applications in biology where long-term emitting fluorescent bio-compatible nanoprobes are still missing.