This study investigates the elementary excitations of single-photon emitters (SPEs) in hexagonal boron nitride (hBN). Using resonant inelastic X-ray scattering (RIXS) and photoluminescence (PL) spectroscopy, the researchers identify an elementary excitation at 285 meV that gives rise to a series of harmonics correlated with SPEs. The study highlights the role of Nπ* antibonding orbitals in shaping the electronic states of the emitters. The discovery provides new insights into quantum emission in low-dimensional materials and paves the way for future investigations in other platforms. hBN is a versatile material with applications in multiple scientific fields due to its properties, including air stability, hyperbolic dispersion, and strong optical non-linearities. The discovery of SPEs in hBN has sparked scientific interest due to their room temperature operation, high brightness, frequency tunability, stability, narrow linewidth, and optically detected magnetic resonances. However, the microscopic details of the origin and electronic levels of these emitters remain unclear. The study reveals that the elementary excitation at 285 meV is associated with the Nπ* antibonding orbitals and is responsible for the quantum emission in hBN. The RIXS measurements show that the excitation propagates up to 2.3 eV through multiple regular harmonics. The researchers also compare the RIXS data with PL experiments and find a correlation between the RIXS harmonics and the SPEs observed in PL spectra. The results suggest that the elementary excitation at 285 meV is a fundamental component of the quantum emission in hBN. The study also explores the role of donor-acceptor pairs (DAP) in the recombination processes that lead to the emission of single photons. The analysis of the PL data shows that the energy of the harmonics follows a linear trend, indicating a common intrinsic nature. The results suggest that the elementary excitation at 285 meV is a key factor in the quantum emission in hBN. The study concludes that RIXS is an important tool for the discovery and comprehension of low-dimensional photonic quantum materials. The findings provide a solid basis for a complete description of single-photon emitters in hBN and highlight the importance of Nπ* orbitals in the electronic transitions responsible for single-photon emission. The study also suggests that the similarities between the RIXS spectrum at the Nπ* resonance of hBN and N2 molecules could indicate a participation of N-N-like structures in the generation of SPEs.This study investigates the elementary excitations of single-photon emitters (SPEs) in hexagonal boron nitride (hBN). Using resonant inelastic X-ray scattering (RIXS) and photoluminescence (PL) spectroscopy, the researchers identify an elementary excitation at 285 meV that gives rise to a series of harmonics correlated with SPEs. The study highlights the role of Nπ* antibonding orbitals in shaping the electronic states of the emitters. The discovery provides new insights into quantum emission in low-dimensional materials and paves the way for future investigations in other platforms. hBN is a versatile material with applications in multiple scientific fields due to its properties, including air stability, hyperbolic dispersion, and strong optical non-linearities. The discovery of SPEs in hBN has sparked scientific interest due to their room temperature operation, high brightness, frequency tunability, stability, narrow linewidth, and optically detected magnetic resonances. However, the microscopic details of the origin and electronic levels of these emitters remain unclear. The study reveals that the elementary excitation at 285 meV is associated with the Nπ* antibonding orbitals and is responsible for the quantum emission in hBN. The RIXS measurements show that the excitation propagates up to 2.3 eV through multiple regular harmonics. The researchers also compare the RIXS data with PL experiments and find a correlation between the RIXS harmonics and the SPEs observed in PL spectra. The results suggest that the elementary excitation at 285 meV is a fundamental component of the quantum emission in hBN. The study also explores the role of donor-acceptor pairs (DAP) in the recombination processes that lead to the emission of single photons. The analysis of the PL data shows that the energy of the harmonics follows a linear trend, indicating a common intrinsic nature. The results suggest that the elementary excitation at 285 meV is a key factor in the quantum emission in hBN. The study concludes that RIXS is an important tool for the discovery and comprehension of low-dimensional photonic quantum materials. The findings provide a solid basis for a complete description of single-photon emitters in hBN and highlight the importance of Nπ* orbitals in the electronic transitions responsible for single-photon emission. The study also suggests that the similarities between the RIXS spectrum at the Nπ* resonance of hBN and N2 molecules could indicate a participation of N-N-like structures in the generation of SPEs.