Low temperature investigations and surface treatments of colloidal narrowband fluorescent nanodiamonds

TL;DR

This study explores the optical properties of colloidal nanodiamonds with silicon vacancy centers, focusing on low-temperature behavior and surface treatments to enhance their crystalline quality and single-photon emission capabilities.

Contribution

It introduces a method to improve nanodiamond quality via air oxidation and analyzes the temperature-dependent optical features of SiV centers.

Findings

Oxidation reduces ensemble linewidth and enhances single-photon purity.

Single SiV centers exhibit temperature-dependent zero-phonon-line fine structure.

Surface treatments improve the crystalline quality of nanodiamonds.

Abstract

We report fluorescence investigations and Raman spectroscopy on colloidal nanodiamonds (NDs) obtained via bead assisted sonic disintegration (BASD) of a polycrystalline chemical vapor deposition film. The BASD NDs contain in situ created silicon vacancy (SiV) centers. Whereas many NDs exhibit emission from SiV ensembles, we also identify NDs featuring predominant emission from a single bright SiV center. We demonstrate oxidation of the NDs in air as a tool to optimize the crystalline quality of the NDs via removing damaged regions resulting in a reduced ensemble linewidth as well as single photon emission with increased purity. We furthermore investigate the temperature dependent zero-phonon-line fine-structure of a bright single SiV center as well as the polarization properties of its emission and absorption.