Fig. 1. Optical microscope photos of diamond samples before and after the irradiation and annealing experiments

Fig. 2. Fluorescence images and phosphorescent images of diamond samples before and after irradiation and annealing experiments.

Fig. 3. Ultraviolet-visible-near-infrared spectra of diamond samples before and after irradiation and annealing experiments (R means irradiation, and T means annealling). (a) M1, M2, and M7 samples before irradiation; (b) M1, M2, and M7 samples after irradiation; (c) M1, M2, and M7 samples after annealing

Fig. 4. Infrared spectra of diamond samples before and after irradiation and annealing experiments. (a) M2 sample; (b) brown shaded part of M2 sample; (c) M7 sample; (d) brown shaded part of M7 sample

Fig. 5. Photoluminescence spectra of sample measured by 405 nm laser before and after irradiation and annealing experiments. (a) M2 sample; (b) M7 sample

Fig. 6. PL spectra of diamond sample measured by 532 nm laser before and after irradiation and annealing experiments. (a) PL spectra before irradiation; (b) PL spectra after irradiation; (c) PL spectra after annealing; (d) image of sample under irradiation after annealing

Fig. 7. PL spectra of diamonds for 532 nm laser irradiation after annealing，and variation of [NV]^- fluorescence intensity with irradiation dose. (a) PL spectra of diamonds for 532 nm laser irradiation after annealing; (b) variation of fluorescence intensity of [NV]^- with irradiation dose

Fig. 8. PL spectra of diamond for 532 nm laser irradiance after annealing, and variation of fluorescence intensity of [NV]^- with annealing temperature. (a) PL spectra of diamond for 532 nm laser irradiance after annealing; (b) variation of fluorescence intensity of [NV]^- with annealing temperature