High Resolution Temperature-Resolved Spectroscopy of the Nitrogen Vacancy ${}^{1}E$ Singlet State Ionization Energy

Abstract

The negatively charged diamond nitrogen-vacancy (${\mathrm{NV}}^{-}$) center plays a central role in many cutting edge quantum sensing applications; despite this, much is still unknown about the energy levels in this system. The ionization energy of the ${}^1\mathrm{E}$ singlet state in the ${\mathrm{NV}}^{-}$ has only recently been measured at between 2.25 eV and 2.33 eV. In this work, we further refine this energy by measuring the ${}^1\mathrm{E}$ energy as a function of laser wavelength and diamond temperature via magnetically mediated spin-selective photoluminescence (PL) quenching; this PL quenching indicating at what wavelength ionization induces population transfer from the ${}^1\mathrm{E}$ into the neutral ${\mathrm{NV}}^0$ charge configuration. Measurements are performed for excitation wavelengths between 450 nm and 470 nm and between 540 nm and 566 nm in increments of 2 nm, and for temperatures ranging from about 50 K to 150 K in 5 K increments. We determine the ${}^1\mathrm{E}$ ionization energy to be between 2.29 and 2.33 eV, which provides about a two-fold reduction in uncertainty of this quantity. Distribution level: A. Approved for public release; distribution unlimited.

9 pages, 5 figures, invited manuscript for Recent Advances in Diamond Science and Technology - SBDD XXIX special issue of Physica Status Solidi (a)