Molecular-sized fluorescent nanodiamonds

Abstract

Doping of carbon nanoparticles with impurity atoms is central to their application. However, doping has proven elusive for very small carbon nanoparticles because of their limited availability and a lack of fundamental understanding of impurity stability in such nanostructures. Here, we show that isolated diamond nanoparticles as small as 1.6 nm, comprising only ∼400 carbon atoms, are capable of housing stable photoluminescent colour centres, namely the silicon vacancy (SiV). Surprisingly, fluorescence from SiVs is stable over time, and few or only single colour centres are found per nanocrystal. We also observe size-dependent SiV emission supported by quantum-chemical simulation of SiV energy levels in small nanodiamonds. Our work opens the way to investigating the physics and chemistry of molecular-sized cubic carbon clusters and promises the application of ultrasmall non-perturbative fluorescent nanoparticles as markers in microscopy and sensing.

Diamond Nanophotonics

“…Here, excitation and emission in the red or near-infrared spectral range allow for deep tissue imaging and aid in avoiding tissue autofluorescence. In this context, the recent discovery of stable SiV centers in nanodiamonds as small as 2 nm is especially interesting as it brings the size of fluorescent nanodiamonds down to the level of the size of typical dye molecules employed in biology [59] .…”

Two-site diamond-like point defects as new single-photon emitters

“…Until the appearance of our paper [23], it has been a quite elusive topic whether molecular-sized diamonds can feasibly host colour centers, just like larger nanodiamonds or bulk diamond can. This was the result of general unavailability of nanodiamonds in this size [24], as well as the low stability of these colour centres, e.g.…”

Near-Infrared Fluorescence from Nanodiamond for Multimodal Bioimaging

“…The defect-originated color centers in ND are suitable for numerous possible applications ranging from quantum information processing as single-photon sources [3][4][5] to optical markers for cellular imaging [1,2,6]. The most well-studied and utilized defect to date is nitrogen-vacancy (NV) color centers which appear in neutral (NV 0 ) and negative (NV -) charge states with zerophonon lines (ZPL) at 575 nm (2.156 eV) and 637 nm (1.945 eV), respectively [3,5,7].…”

“…To circumvent the obvious limitation associated with the use of NV centers, the potential use of fluorescence in the near-infrared region from silicon-vacancy (with ZPL at 737 nm) [6] or some of nickel (Ni) centers [10] would be an alternative for the detection, as its emission is far away from most of the biomolecules and commercial dyes. Synthetic diamond grown by the high-pressure hightemperature technique uses a nickel-containing metallic catalyst, and nickel is usually inevitably included in the resulting diamond.…”