[@Stoll2006] using the spin Hamiltonian parameters given in Table \[tab:spin\_hamiltonian\_parameters\].[]{data-label="fig:si29_epr"}](graphs_epr_principal_directions_si29_epr){width="\columnwidth"}

A previous DFT study into silicon-containing defects in diamond identified SiVN as a simple and stable defect candidate in high-nitrogen high-silicon diamond [@Goss2007]. DFT calculations of the hyperfine parameters of the silicon and nitrogen in [$\mathrm{SiVN}^0$]{}(improving on previously-reported values [@Goss2007]) were used as a guide for experimental parameters \[Table \[tab:spin\_hamiltonian\_parameters\]\]. To confirm the presence of silicon in the defect, long-term scans designed to increase the signal-to-noise enough to easily identify any $^{29}\mathrm{Si}$-related spectrum (approximately of the natural abundance of $^{28}\mathrm{Si}$) were performed. These scans measured approximate replicas of the primary spectrum split by a nucleus of $I=1/2$, approximately abundant, which we identify as $^{29}\mathrm{Si}$ \[Fig \[fig:si29\_epr\]\]. The hyperfine interaction strengths $A_{1,2,3}=\num{98.24}$, $\num{98.13}$, $\SI{94.47}{\mega\hertz}$ are remarkably similar to the DFT-calculated values ($\num{87}$, $\num{89}$, $\SI{92}{\mega\hertz}$, respectively) and have identical directions. A similar case is found for the nitrogen hyperfine, where the experimentally-measured values are within of the DFT-calculated values. When taken in conjunction with the dopant and treatment history of [Sample G]{}, these data are enough to conclusively assign the observed spectrum to the defect [$\mathrm{SiVN}$]{}\[Fig \[fig:orbitals\](a)\].

The expected charge state of [$\mathrm{SiVN}$]{}can be calculated from the group theoretical descriptions of the 