Fundamentals of Radiative Transitions of Ions and of Ion Pairs in Solids

Baldassare Di Bartolo

Quanlin Liu

Radiative transitions are quantum-state transitions in matter quantum systems (such as atoms， ions， and molecules) caused by their interaction with the electromagnetic field， and accompanied by the emission or absorption of photons.Their theoretical description involves physical theories including quantum mechanics and quantum electrodynamics， as well as mathematical tools such as spherical tensors and group theory.Focusing on radiative transitions of doped ions in solids， this paper summarizes earlier related theories and aims to concisely introduce fundamental theories and mathematical expressions while maintaining rigor， and to clearly describe the underlying physical pictures and mechanisms.The topics covered include atomic quantum states， the quantized electromagnetic field， multipole radiative transitions and selection rules， stimulated absorption， stimulated emission and spontaneous emission， transition probability and excited-state lifetimes.The article also discusses f-f and 4f-5d transitions of rare-earth ions and dd transitions of transition-metal ions， involving Judd -Ofelt theory， crystal-field theory， electronvibration coupling， and the Dorenbos model， as well as statistical analysis， machine learning， and firstprinciples methods.This work may provide a theoretical reference for the study of rare-earth-and transition-metaldoped luminescent materials.Keywords： radiative transition； theory； physical picture； f-f transition； d-d transition； 4f-5d transition 文章编号： 1000-7032(XXXX)XX

FRANK B. ROSMEJ, Valery Alexandrovich Astapenko, Valery S. Lisitsa

Zoltan Fried, Lloyd C. Kannenberg

Juan Francisco Lam

Coupled ion pairs in solids have played an important role in the development of new solid-state lasers. The long-range interaction among two or more ions provides a channel for the inversion of population, leading to the discovery of new emission lines. Because of the relatively large optical cross sections, coupled ion pairs may provide new media for the implementation of a solid-state phase conjugate mirror. We present a theory of optical phase conjugation via four-wave mixing in such novel materials. For a model ion-doped solid-state system, the calculations give the following conclusions. First, the spectral linewidth is proportional to the square root of the intensity of the radiation field in an inhomogenously broadened material for fixed ion density. Second, the linewidth decreases with increasing ion density for the fixed intensity level. And last, the saturation intensity also decreases with increasing ion density for the fixed optical intensity. The behavior of the linewidth and the saturation intensity are attributed to the strong interaction among two nearest-neighbor ion pairs, which leads to the generation of additional energy dumping pathways.

Olga A. Kocharovskaya, Roman L. Kolesov, Yuri V. Rostovtsev +1 more

Summary form only given. Recently, it was predicted that laser radiation can be used to manipulate very efficiently nuclear transitions at gamma-ray energies in solids. It results in both drastic qualitative and strong qualitative modifications of the Mossbauer spectra under the action of coherent optical radiation. The solid sample represents a host matrix where high densities of the ions are embedded by doping. The ions should possess both Mossbauer gamma-ray and optical electronic transitions favorable for the desired effects to be observed. Basically one needs Mossbauer-active ions with strong and sharp optical lines. The latter condition is typically satisfied for rare-earth and transition-metal ions in crystalline hosts and, remarkably, the majority of them are also Mossbauer-active.