plates. Samples B – F were each subsequently annealed under stabilizing pressure for at [1600, 1800, ..., ]{}, respectively: each sample was annealed only once (i.e. [Sample D]{} was annealed at only). [Sample G]{}was annealed at for under stabilizing pressure. All samples were polished post-anneal to remove any etched or graphitic material and provide parallel, low-roughness faces for optical measurements. Each sample was approximately $3\times3\times\SI{1.6}{\milli\meter}$.

As a consequence of the charge transfer effect ($\S\ref{subsec:charge_transfer}$), the annealing behavior of a given defect can be confused with its charge transfer properties if care is not taken to initialize the crystal to a known state before each measurement. We therefore perform all measurements immediately following either UV exposure (the “UV state”) or heating in the dark at for (the “heated state”): the sample is kept in the dark between treatment and measurement. For the UV state, samples were exposed using the xenon arc lamp of a DiamondView instrument for per face; heating was performed under a dry nitrogen atmosphere in a tube furnace (Elite Thermal Systems Ltd.) for at . EPR measurements were performed at X-band using a Bruker EMX-E spectrometer with attenuator to avoid microwave power saturation, and ER4122SHQ resonator. EPR measurements 