Optical absorption spectra of Ge* ions in KCI and KBr crysMs have been investigated in h temperature m g e IS-300 K. In the uiplet-suUetured spin-orbit-allowed C band, the C1-G band spiilting was observed to be larger than that of the C Z -C ~ band at low tempemtures. while the W O become equal to each other with increasing temperature. The absorption lieshape has been calculated, by means of the Monte Carlo integration method, for G$+ ions with a h e a r electron-lattice interaction and tetragonal crystal field. Comparing the calculated lineshape with the observed spectra, we conclude that the Gel+ ion is at the off-centre position with the tewgonal field at low temperatures, but is moved into the onbenee position with increasing temperature.
Alkali halide crystals containing a small amount of Tl+-like ions with s2 ground-state electron configuration exhibit three absorption bands due to the electronic transitions (a1J2 4 (al,) (tl,) in the s2 ion centers [l, 21. They have been called A, B, and C bands in order of increasing energy. The A band is due to a spin-orbit-allowed transition, the C band is due to a dipole-allowed transition, while the B band is caused by a vibration-induced transition. The Ag-ion has the electron configuration ( 5~)~ in the ground state. The negative ions have been confirmed to occupy the anion sites of the alkali halide lattice [3]. The absorption and emission spectra of Ag-ions in alkali halide crystals have been studied by several investigators (see for example [3,4]). The magnetic circular dichroism (MCD) spectra of the Ag-center were also previously reported [5]. A detailed study, however, has not yet been made: for example, neither the temperature dependence of MCD spectra nor the g-value were reported. In this note we study the MCD spectra and the g-value of KCI : Agcrystals at various temperatures. mol% of Ag' ions were grown by the Kyropoulos method and they were additively colored in potassium vapor to create Agions. The absorption spectra were measured using a Shimadzu UV-3100 spectrophotometer in the 15 to 300K temperature range. The MCD spectra were measured using a JASCO J-40A spectropolarimeter. The magnetic field was applied to the crystals in the [OOl] crystal direction. An electromagnet was used to produce fields up to 1.4 T. Fig. 1 shows the absorption spectrum at 16 K of an additively colored KCl : Ag' crystal with a thickness of 0.7 mm. The spectrum exhibits the C band due to Ag-centers at 4.35 eV in addition to the absorption bands due to the F, M, and R color centers. The A and B bands are too weak to be observed clearly in the absorption spectrum [4]. In various s2 ion centers, a charge-transfer-type D band has been observed near and on the high-energy side of the C band [l, 21. However, no absorption band appears in the wide range of 1 eV on the high-energy side of the C band in KCl: Ag-.The absorption and MCD spectra of the C band observed at 16 and 287 K are shown in Fig. 2. It can be seen that the C band has a nonstructured shape. The lineshape is symmetric at high temperatures but asymmetric at low temperatures where the slope of the low-energy side is steeper than that of high-energy side. These results are different from the C bands of other s2 ion centers such as Sn2+, Tl', and Pb2+ [6]. Regarding the MCD Single crystals of KC1 containing 3.5 x I ) Kamigamo, Kyoto 603, Japan. ' ) Kongju, Chungnam 314-701, Korea.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.