Atomic displacement by X-ray excitation in NaCl crystal containing Cu⁺ ions

The x-ray excitation spectra around Cu K-edge in sodium chloride crystals containing a small amount of Cu⁺ ions are measured at 11K to 200K. We found Cu⁺ ion displacements and growths to micro-clusters (micro-crystals) of CuCl₂ in sodium chloride crystal by x-ray irradiation. The trace of the formation is presented by observing the XAFS spectra and XEOL (X-ray Excitation Optical Luminescence) intensities at various temperatures. At low temperature below about 50 K, the micro-clusters or the micro-crystal s of CuCl₂ hardly create. The higher temperature moves the ions faster and further, and makes more active to form the CuCl₂ micro-crystals in bulk. The process of moving of the Cu⁺ ion is discussed.