On the UV Absorption of Heavy Metal Ions in Alkali Halide Crystals II. Interpretation of the Temperature Dependences of the UV Dipole Strength

Abstract

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.

The Parity‐Forbidden 4f5 → 4f5 Transition of the Sm3+ Ion in CaF2

“…The vibronic mixing gives rise to an absorption band that grows in intensity as temperature is raised. Accurately speaking, the idtensity of the vibration-induced band is proportional to coth (hv/ZkT) in the approximation of linear electron-phonon interaction [16, 171 ; the intensity is proportional t o 7' (temperature) a t high temperatures, but is constant at low temperatures near T = 0 K. The coth (hv/2kT) law was confirmed in various ionic crystals, e.g., T1+-doped alkali halides [18,191, KBr [ZO], Cu+-doped NaCl [19], Ag+-doped alkali halides [21], NiSO, -7 H,O [ 2 2 ] . As seen in Fig.…”

Luminescent decay and spectra of impurity-activated alkali halides under high pressure

“…The EL interaction Hamiltonian for a parity-forbidden transition is given by [50] between the impurity and the nearest neighbors are nearly equal, so that the force constant is small and the frequency of the resonant mode is quite low. In fact, the balance of forces may be such that the impurity ion is unstable at the center of symmetry and so moves to an off-center position (or rather, tunnels among several equivalent off-center positions).…”

“…The EL interaction Hamiltonian for a parity-forbidden transition is given by [50] HEL = ArQ + BrQ-Q+ + + ArQ~ + BrQdQ~ + (24)…”

Luminescence and evaluation of trapping parameters in NaMgSO4Cl: X (X=Cu or Ce) phosphor

“…Cu þ emission has also been used in thermo luminescence dosimetry phosphors such as LiF: Mg, Cu, P [16], Li 2 B 4 O 7 : Cu [17,18] Cu þ emission can also be used as blue component of full color electro luminescent display devices [19,20]. However, more common valency of copper is 2 þ , and the methods for incorporating monovalent Cu have not been systematically worked out e.g., in several works results on Cu þ emission in alkali halides have been mentioned [21][22][23][24][25][26][27][28][29][30], but the procedure adopted for incorporating Cu in monovalent form has not been given. Several authors on the other hand, mention that incorporation of Cu þ can be difficult [31].…”