X-ray absorption and luminescence studies of $Ba2Ca(BO3)2:$ $Ce3+/Na+$ phosphors

X-ray excited optical luminescence (XEOL) spectroscopy has been used to investigate the optical emission properties of $Ce3+$ activated $Ba2Ca(BO3)2$ with a charge-compensating $Na+$ and the results are compared with the optical emission properties from UV excitation. Further, x-ray absorption near-edge structure (XANES) has been employed to study the chemical environment and energy transfer efficiency to optical emission upon x-ray excitation. XEOL results agree well with optical emission with UV excitation. XANES results across various absorption edges show that while the chemical environment of host materials does not change significantly with doping, luminescence yield decreases significantly at absorption edges due to an abrupt change in the de-excitation mechanism.