The nitrogen-vacancy (NV) center in diamond is a widely-utilized system due to its useful quantum properties. Almost all research focuses on the negative charge state (NV−) and comparatively little is understood about the neutral charge state (NV0). This is surprising as the charge state often fluctuates between NV0, and NV−, during measurements. There are potentially under utilized technical applications that could take advantage of NV0, either by improving the performance of NV−, or utilizing NV0, directly. However, the fine-structure of NV0, has not been observed. Here, we rectify this lack of knowledge by performing magnetic circular dichroism (MCD) measurements that quantitatively determine the fine-structure of NV0. The observed behavior is accurately described by spin-Hamiltonians in the ground and excited states with the ground state yielding a spin-orbit coupling of λ=2.24±0.05 GHz and a orbital g−factor of 0.0186±0.0005. The reasons why this fine-structure has not been previously measured are discussed and strain-broadening is concluded to be the likely reason
@article{arxiv.1905.09037,
title = {The fine structure of the neutral nitrogen-vacancy center in diamond},
author = {M. S. J. Barson and E. Krausz and N. B. Manson and M. W. Doherty},
journal= {arXiv preprint arXiv:1905.09037},
year = {2019}
}