Nanomechanical method to gauge emission quantum yield applied to NV-centers in nanodiamond

TL;DR

This paper introduces a nanomechanical technique to measure the quantum yield of fluorophores, demonstrated on NV centers in nanodiamonds, revealing they can have quantum efficiencies less than one.

Contribution

The paper presents a novel nanomechanical method for gauging emission quantum yield by controlling the local optical environment of fluorescent sources.

Findings

NV centers in nanodiamonds have quantum yields less than one

The method is compatible with existing near-field microscopy setups

Quantum efficiency variations can be precisely measured using the proposed technique

Abstract

We present a technique to nanomechanically vary the distance between a fluorescent source and a mirror, thereby varying the local density of optical states at the source position. Our method can therefore serve to measure the quantum efficiency of fluorophores. Application of our technique to NV defects in diamond nanocrystals shows that their quantum yield can significantly differ from unity. Relying on a lateral scanning mechanism with shear-force probe-sample distance control our technique is straightforwardly implemented in most state-of-the-art near-field microscopes.