The current research conducts calculations of Core Electron Binding Energies (CEBEs) for NBD/QC, NBN/PPL, and NBA in the gas phase. As of now, experimental measurements for the C1s CEBEs of norbornyl derivatives are unavailable, and accurate theoretical calculations are lacking, except for estimations . The present method, based on Density Functional Theory (DFT), has been validated using approximately 120 compounds, including carbon hydrates and substituted benzenes. Validation includes both adiabatic and vertical CEBEs for other organic and biomolecules in the gas phase, utilizing X-ray Photoelectron Spectroscopy (XPS) measurements with high precision . The averaged absolute deviation (AAD) stands at 0.15 eV, 0.14 eV, 0.14 eV, and 0.11 eV for C1s, N1s, O1s, and F1s, respectively .