Photo-excitation dynamics of color centers in diamond

The negatively-charged nitrogen-vacancy (NV^-) center in diamond is among the most promising candidates for developing quantum technologies in the realm of solid state materials. The projects reported in this thesis tackle the ongoing challenges of understanding the electronic structure and charge state conversion mechanisms in the neutral and the negatively-charged states of the NV center using transient absorption (TA) spectroscopy. The results from such investigations reveal high-energy excited states localized in the conduction band (CB) of NV^-. In the neutral state NV⁰, a series of transitions reminiscent of the Rydberg states, followed by the onset of the hole excitation threshold in NV⁰, were observed. The population dynamics intrinsically and between these two charge states are also reported, including the electron tunneling mechanism of the NV^-+N⁺→NV⁰+N⁰ process. While the observations in the NV center have improved the overall understanding of this system, there exists multiple open questions that cannot be answered due to the necessary existence of substitutional nitrogen in the lattice. To remove this parameter, the vacancy center is also studied. The precursor system to all vacancy-related defects in diamond, including NV, the vacancy center also exhibited very similar features, especially in the neutral state. Many of the charge conversion processes between the neutral and the negatively-charged states persist even with the lack of substitutional nitrogen to mediate charge carriers. The results from the vacancy center paved way towards the understanding not only in the NV center, but also novel vacancy-related defects in diamond as well as silicon carbide (SiC).