Absorption spectra of Ag+ doped NaCl, KCl, KBr, and KJ are measured at low temperatures in the spectral range from 6.8 to 4.4 eV. The fine structure of the Ag+ bands and their temperature dependence are investigated. The oscillator strenghts at low temperatures are in the order of 10−3. These Ag+ absorption bands are due to vibronic transitions: The parity‐forbidden electronic transitions 4d10 → 4d95s are allowed by an interaction with odd phonons. The temperature dependence of the oscillator strengths can be fitted by a function which takes care of one‐ and two‐phonon processes. This function contains an effective lattice frequency which turns out to lie on the low‐frequency side of the acoustic branches of the host lattice near the resonance mode of the Ag+ ion.
UV absorption spectra of -4g+, Cut, and TIt centres in alkali halide crystals are measured between 5 and 300 O K in order to determine the electronic fine struct'ure of the bands as well as the magnitude and temperature dependence of the UV dipole strength. The structure and temperature dependence of the spectra are interpreted in terms of electron-phonon interaction and off-centre effects.UV-Absorptionsspektren von Agt-, Cut-und T1+-Zentren in Alkalihalogenid-Kristallen werden zwischen 5 und 300 O K gemessen, um die elektronische Feinstruktur der Banden und die GroBe und Temperaturabhangigkeit, der UV-Dipolstarke zu bestimmen. Die Struktur und Tempcraturabhangigkeit der Spektren werden durch Elektron-Phonon-Wechselwirkung und ,,Off-centre"-Effektc intcrpretiert.
The absorption spectrum of Ag+ doped RbCl is measured at various low temperatures in the spectral range from 6.4 to 5.0eV. The temperature dependence of the Ag+ dipole strength in RbCl is different from that found in NaCI, KCl, and KBr. The different temperature behaviours are interpreted as being due to the different lattice potentials seen by the Ag+ in the various host crystals. The static potentials for Ag+ in the crystals are calculated by a semiphenomenologicel method. For NaCl, KCI, and KBr a potential minimum is found a t the symmetry centre. For RbCI, however, a potential barrier exists a t the symmetry centre and potential mimima occur a t 0.25A away from the centre in the [ill] direction.
Das Absorptionsspektrum vonAg+-dotiertem RbCl wird bei verschiedenen tiefen Temperaturen im Spektralbereich von 6,4 bis 5,O eV gemessen. Die Temperaturabhangigkeit der Dipolstiirke zeigt einen anderen Verlauf als er bisher von Ag+ in NaCl, KCl und KBr bekannt ist. Die verschiedenen Temperaturabhlngigkeiten der Dipolstarke werden mit verschiedenen Gitter-Potentialen erklart, die auf das Ag+ Ion in den verschiedenen Wirtskristallen wirken. Mit einer halbklassischen Methode werden die statischen Potentiale fur das Ag+ Ion in den Kristallen berechnet. Die Berechnungen ergeben fur NaCI, KCl und KBr ein Potentialminimum im Syrnmetriezentrum, fur RbCl dagegen einen Potentialberg im Symmetriezentrum und Potentialminirna 0,25 A auSerhalb in [ 1111-Richtung.
The different temperature dependences of the UV dipole strength of forbidden electronic Ag+, CU+, and T1+ transitions in alkali halide crystals are interpreted by electron-phonon interaction, anharmonicity of phonons, off-centre effects, and thermal relaxations of the centres.Die verschiedenen Temperaturabhangigkeiten der UV-Dipolstarke von verbotenen, elektronischen Ag+-, Cu+-und Tl+-Ubergangen in Alkalihalogenid-Kristallen werden durch Elektron-Phonon-Wechselwirkung, Anharmonizitat der Phononen, ,,Off-centre"-Effekte und thermische Relaxationen der Storzentren gedeutet.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.