1：Experimental Design and Method Selection:

The study involved controlled electron beam irradiation of ND pellets to generate vacancies, followed by annealing and surface modification. Fluorescence properties were analyzed using steady-state and time-resolved spectroscopy, including Time-Correlated Single Photon Counting (TCSPC) and Fluorescence Lifetime Imaging Microscopy (FLIM).

2：Sample Selection and Data Sources:

Oxidized nanodiamond (OND) samples with a nitrogen content of about 100 ppm were used, prepared from aqua regia cleaned MSY

3：0–05 NDs. Samples were pressed into pellets for irradiation and analysis. List of Experimental Equipment and Materials:

Equipment included a linear electron accelerator (MB10-30MP, Mevex Corp.), confocal microscope (IX71, Olympus), spectrometer (iHR320, HORIBA JobinYvon), FLIM setup with diode laser (513 nm, Becker & Hickl), AFM (MFP-3D, Oxford Instruments), SEM (ULTRA 55, Carl Zeiss), XRD (ULTIMA IV, RIGAKU), ATR-IR, and XPS. Materials included nanodiamonds, argon gas, air, hydrogen gas, ammonia gas, and polyvinyl alcohol.

4：Experimental Procedures and Operational Workflow:

ND pellets were irradiated with 10 MeV electrons at varying fluences, annealed at 800°C in argon, and subjected to surface modifications (oxygen, hydrogen, nitrogen termination). Fluorescence spectra and lifetimes were measured before and after treatments using specified lasers and filters. Particle size and NV center counts were determined via AFM and photon antibunching measurements.

5：Data Analysis Methods:

Data were analyzed using bi-exponential fitting for fluorescence lifetimes, saturation models for intensity and lifetime dependencies, and statistical methods for particle size and fluorescence correlations. Software included SPCimage for FLIM data analysis.