For the first time, stability of KCl single crystals doped with sodium impurity ions was analyzed via optical absorption and luminescence methods. Using characteristic bands absorption, as well X-ray tunnel luminescence, ascribed to radiation defects exciton-like formations localized near impurity, removal Na+ from regular cation sites into nanosized clusters in KCl:Na stored for a long time at...

The theory of the crystal-field splitting, V,, of the J = I level of an ortho impurity in a parahydl-ogen matrix, due to the coupling of the rotational motion of the ortho molecule to the lattice vibrations, is developed taking due account of the quantum-crystal nature of the solid. Two contl-ibutions to V, are identified, both arising from the anisotropy in the lattice vibrations. One contribu...

A crystal field analysis of the energy level structure of Cr3+ in MgO crystal is performed, using the exchange charge model of the crystal field theory. The crystal field parameters acting on the optical electrons of Cr3+ are calculated from the crystal structure data; good agreement between the calculated and observed energy levels of Cr3+ in the title host is demonstrated. The Stokes shift S=...

Pure and Ni2þ doped KZnF3 single crystals were studied using the combination of the DFT-based ab initio methods, crystal field theory and experimental spectroscopic techniques. The electronic, optical and elastic properties have been calculated and compared with available experimental data and good agreement was achieved. Elastic anisotropy of pure KZnF3 was modeled; calculations of the sound v...

The mechanisms by which macromolecular impurities degrade the diffraction properties of protein crystals have been investigated using X-ray topography, high-resolution diffraction line shape measurements, crystallographic data collection, chemical analysis, and two-photon excitation fluorescence microscopy. Hen egg-white lysozyme crystals grown from solutions containing a structurally unrelated...

It is said that the microgravity environment positively affects the quality of protein crystal growth. The formation of a protein depletion zone and an impurity depletion zone due to the suppression of convection flow were thought to be the major reasons. In microgravity, the incorporation of molecules into a crystal largely depends on diffusive transport, so the incorporated molecules will be ...