A NEW FUNDAMENTAL HYDROGEN DEFECT IN ALKALI-HALIDESReport as inadecuate




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Abstract : Atomic hydrogen in neutral H0 and negative H- form on substitutional and interstitial lattice sites gives rise to well-characterized model defects in alkali-halides U, U1, U2, U3 centers, which have been extensively investigated in the past. When studying the photo-decomposition of OH- defects, a new configuration of atomic charged hydrogen was discovered, which can be produced in large quantities in the crystal and is apparently not connected to any other impurity. This new hydrogen defect does not show any pronounced electronic absorption, but displays a single sharp local mode band at 1114 cm-1 in KCl with a perfect √2 H → D isotope shift. The defect can be produced by various UV or X-ray techniques in crystals doped with OH-, SH- or H- defects. A detailed study of its formation kinetics at low temperatures shows that it is primarily formed by the reaction of a mobile Cl-2 crowdion H-center with hydrogen defects. Attempts will be discussed to derive from the local mode and formation-kinetics data a consistent model for this new hydrogen defect.





Author: S. Morato F. Lüty

Source: https://hal.archives-ouvertes.fr/



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