ENDOR Study of Atomic Hydrogen on Cation Sites in KCl Doped with Sr⁺⁺

Abstract

Atomic hydrogen trapped on cation sites (Ht,,-centres) next to Sr2+ in [ l l O ] in KC1 is investigated by ENDOR and ENDOR-induced ESR. The superhyperfine and quadrupole interactions and their relative signs of three types of inequivalent nearest C1-nuclei are determined. The transition energy for the first excited vibrational hydrogen state is derived from the superhyperfine temperature dependence. A further Ht,,-centre is found with Sr2+ probably on a [200] site. The superhyperfine data are discussed considering the local lattice distortion around the cation vacancy.Atomarer Wasserstoff auf Kationenplatz (Ht,.,-Zentren) neben einem Sr2+-Ion in [110] wird in KCI mit Hilfe von ENDOR und ENDOR-induzierter ESR untersucht. Die Superhyperfein-und Quadrupol-Wechselwirkungen und ihr relatives Vorzeichen werden fur drei nichtaquivalente nachste C1-Nachbarn bestimmt. Die Anregungsenergie fur den ersten angeregten Schwingungszustand des Wasserstoffs wird aus der Temperaturabhingigkeit der ENDOR-Linien abgeleitet. Es wird ein weiteres Ht, ,-Zentrum gefunden, bei welchem ein Sr2+-Ion vermutlich auf einem [200]-Platz sitzt. Die Superhyperfein-Wechselwirkungen werden unter Berucksichtigung der lokalen Gitterverzerrung um die Kationenleerstelle diskutiert.

Atomic Hydrogen Centres in LiF–H− and LiF–H−, Mg2+ Crystals

“…Due to the presence of Mg2+ along (1 lo), the six nearest F-neighbours consist of three pairs of nonequivalent nuclei which were labelled as a, p, and y. The configuration of a, p, y ions is the same as reported for the H:,,(Ca2+) [5,6] (Fig. 3).…”

“…[5] and Studzinski et al [6], using ESR and ENDOR methods, that the Ho-centres are converted to H:,,-centres on warming above 130 K in the KC1-SH-and RbC1-SH-crystals, additionally doped with divalent cations. To produce HY,,-centres one lets Ho-centres diffuse into cation vacancies provided by the doping with divalent cations like Ca2+, Sr2+ [5, 61. This paper reports the results of electron spin resonance measurements of the hydrogen atom centres in LiF-H-and LiF-H-, Mg2+.…”

H ‐Centres in LiFH−, Mg2+

“…Atomic hydrogen can be trapped at substitutional cation sites in alkali halides additionally doped with divalent cations [l, 21. It was shown by Hoentzsch and Spaeth [l] and Studzinski et al [2] that the introduction of divalent cations like CaZ+ or Sr2+ produces in KClLOHand RbC1-OH-H:,,-centres perturbed by the impurity because the impurity-vacancy dipoles remain unaffected by irradiation.…”

Endor Spectroscopy

“…F and H color centers can be formed in inorganic host crystals by ionizing radiation [155][156][157][158][159][160][161][162][163][164][165][166][167][168][169][170][171][172]. The centers formed have been characterized by ENDOR measurements.…”