Diamond nitrogen-vacancy center charge state ratio determination at a given sample point

Abstract

A new, all-optical, relatively simple, and fast method for determining the concentration ratio of negatively charged (NV−) to neutral (NV0) nitrogen-vacancy centers at a given microdiamond point is proposed. The photoluminescence spectra of NV centers were measured at various excitation powers exploiting the photoinduced interconversion effect. An isoemission point was found, and a range of incident laser intensity was determined, under which the total concentration of NV centers of both charge states was conserved, justifying decomposition of the set of photoluminescence curves into NV− and NV0 emission spectra by the standard non-negative matrix factorization (NNMF) procedure. Based on these results, the relative photoluminescence rate of NV− to NV0 centers for HPHT microdiamond was obtained with high accuracy. Possible applications of the new method are discussed.