1：Experimental Design and Method Selection:

The study utilized Raman and photoluminescence (PL) spectroscopies to investigate electron-phonon interactions in h-BN micropowder with carbon and oxygen impurities at temperatures of 83 K and 296 K. The methods were chosen to analyze vibrational modes and luminescence properties.

2：Sample Selection and Data Sources:

A micropowder of hexagonal boron nitride synthesized under nitrogen deficiency conditions with high carbon (2.9 ± 0.3 at.%) and oxygen (0.6 ± 0.1 at.%) impurity content was used. The sample was characterized for morphology, phase, and chemical composition.

3：9 ± 3 at.%) and oxygen (6 ± 1 at.%) impurity content was used. The sample was characterized for morphology, phase, and chemical composition. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included a Perkin Elmer LS55 fluorescence spectrometer, Janis CCS-100/204N helium closed-cycle cryostat, HiCube 80 Eco turbo pump station, LakeShore 335 controller for thermostating, Horiba LabRAM HR800 Evolution spectrometer with He-Ne laser (632.8 nm), Olympus BX series optical microscope, diffraction grating (1800 pcs/mm), CCD detector with Peltier cooling, and Linkam THMS600 cryo-chamber with LNP96 controller.

4：8 nm), Olympus BX series optical microscope, diffraction grating (1800 pcs/mm), CCD detector with Peltier cooling, and Linkam THMS600 cryo-chamber with LNP96 controller. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: PL emission spectra were recorded at 83 K and 296 K in the range of 295–550 nm under 4.28 eV excitation, with spectral slit widths of 2.5 nm. Time-gated measurements with 100 ns gates were used to isolate short-lived luminescence. Raman spectra were measured at the same temperatures using a 632.8 nm laser with 10 mW power. Spectra were corrected for instrumental functions.

5：28 eV excitation, with spectral slit widths of 5 nm. Time-gated measurements with 100 ns gates were used to isolate short-lived luminescence. Raman spectra were measured at the same temperatures using a 8 nm laser with 10 mW power. Spectra were corrected for instrumental functions. Data Analysis Methods:

5. Data Analysis Methods: Data analysis involved Gaussian fitting of PL spectra to extract peak positions and phonon energies, comparison with theoretical models, and calculation of Huang-Rhys parameters. Raman peak shifts were analyzed in terms of temperature effects and anharmonic interactions.