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The amplitude T for ‘free-free’ processes such as bremsstrahlung or photoabsorption by an electron in the continuum in the presence of an external field, is usually written as the matrix element of the radiation operator taken between two continuum states. However, unlike the case when at least one of the states is bound, as in radiative transitions, electron capture or the photo-effect, this expression contains unphysical term, proportional to a delta function, and is not really the physical amplitude Tphys. We first give an a priori definition of Tphys in terms of the scattering parts of the continuum functions, which does not have this delta function term and has an obvious interpretation in terms of time-ordered diagrams. We then show that when the formal amplitude T is modified by a long-distance cutoff, the modified form Tα approaches Tphys as the cutoff is removed. The modified form may be used as the basis for calculation and approximations without the need to introduce further cutoffs at a later stage.

Er 3+-doped fluoroaluminate glasses with different concentrations were prepared by using melt-quenching method. Under a 638 nm laser diode pumping, efficient 3.5 μm emission was observed in the 18 mol% Er 3+ doped sample, which was ascribed to the Er 3+: 4F 9/2 → 4I 9/2 transition. The fluorescence properties such as radiative transition probability, energy level lifetime and branch ratio were predicted by the well-known Judd-Ofelt theory, while the emission and absorption cross-sections were calculated using the Füchtbauer-Ladenburg and McCumber theories, respectively. Both simulated and experimental results show that Er 3+-doped fluoroaluminate material is a promising gain medium for 3.5 μm laser applications.

This work mainly investigates the transition dipole moments (TDMs) and radiative transition probabilities of dipole-allowed transitions between the b1Πu, a′′1Σg+, 13Σg−, 23Σg−, 23Δg, C′3Πu, B′3Σu−,...

Energy levels, hyperfine structure and 2s-2p radiative transition processes of C-like Fe, Co and Ni are studied by performing multiconfiguration Dirac–Hartree–Fock method using the fully relativistic codes GRASP2K. Electron correlation effect on the energies, hyperfine structure constants and radiative transition rates are investigated in detail. Influences of Breit and quantum electrodynamics (QED) effect on energies are studied. Good agreements are found between the results in this work and experimental data. The radiative spectra of the excited states 1s22s2p3 and 1s22p4 of C-like Fe, Co and Ni may provide theoretical support for further experimental study. Since Fe, Co and Ni are important constituent part of experimental apparatus (such as EBIT), the data in this work have important application value for experimental application.

In the context of atomic data computations for astrophysical applications, we review four different types of databases we have implemented for data dissemination: a database for nebular modeling; TIPTOPbase; OPserver; and AtomPy. The database for nebular plasmas is briefly discussed as a study case of a successful project. TOPbase and the OPserver were developed during the Opacity Project, an international consortium concerned with the revision of astrophysical opacities, while TIPbase was part of the Iron Project to calculate radiative transition probabilities and electron impact excitation collision strengths for iron-group ions. AtomPy is a prototype for an open, distributed data-assessment environment to engage both producers and users. We discuss design strategies and implementation issues that may help in the undertaking of present and future scientific database projects.

Radiative transition decay width for was calculated by using twisted mass lattice quantum chromodynamics gauge configurations in this preliminary study. The simulation has been performed on lattices with lattice spacings and lattice size (Ens.C 1), and and lattice size (Ens.B 1) respectively. In this simulation, we have considered the parity mixing effect by using variational method. The calculated central value for the decay width is closer to the experimental data than that in previous lattice studies.

Energy levels and the radiative decay processes of the core-excited configurations 1s2s 2 2p and 1s2p 3 of Be-like ions with Z = 8–54 are studied. Electron correlation effect on the energy levels and the radiative transition rates are studied in detail. Except for E1 radiative transition rates, the E2, M1 and M2 forbidden transitions are also explored. Further relativistic corrections from the Breit interaction, quantum electrodynamics and the finite nuclear size are included in the calculations to make the results more precise. Good agreement is found between our results and other theoretical data.

Reducing the radiative transition’s time constant from thousands of years to a fraction of a second could benefit quantum information schemes.

The radiative transition properties of Eu3+ doped materials can hardly be quantitatively evaluated via traditional Judd-Ofelt (J–O) calculation procedure owing to the lack of available transitions in the absorption spectra. In this work, a new J–O calculation route was proposed and employed to Eu3+ doped alkali borate glasses. Three sets of J–O parameters were obtained by using, respectively, the absorption, emission and excitation spectra, and the average J–O parameters involving more electric dipole transitions than in any individual spectrum were suggested to be used for quantificationally presenting radiative transition properties of Eu3+ in the studied glasses. The radiative transition lifetime of 5D0 level derived by using the J–O parameters was compared with the measured one, and good agreement was achieved. This fact indicated that the proposed J–O calculation route is practicable. Furthermore, the radiative transition rates and fluorescence branching ratios for Eu3+ in the studied borate glasses were calculated.

A new set of oscillator strengths and transition probabilities for EUV spectral lines of seven times ionized tungsten (W VIII) is reported in the present paper. These results have been obtained using the pseudo-relativistic Hartree-Fock (HFR) method combined with a semi-empirical optimization of the radial parameters minimizing the discrepancies between computed energy levels and available experimental data. The final physical model considered in the calculations has been chosen further to a detailed investigation of the configuration interaction in this atomic system characterized by complex configurations of the type 4f145s25p5, 4f145s25p4nl, 4f145s5p6, 4f135s25p6, 4f135s25p5nl and 4f125s25p6nl (nl = 5d, 6s).

Series of 76GeS2·19Ga2S3·5AgCl (GGA) chalcohalide glasses doped with or codoped with Dy3 +, Tm3 + were prepared in this work. Systematical detection of absorption and emission spectra in the near-infrared and mid-infrared region was conducted. For the Dy3 + sole-doped GGA chalcohalide glasses, mainly due to the relatively low efficiency of pumping absorption and poor radiative transition probabilities of mid-infrared emissions, the mid-infrared emissions were hardly to be detected. Through the codoping of Tm3 + with high concentration, several intrinsical processes including the enhancement of pumping absorptive efficiency at 808 nm, cross relaxation process of Tm3 +: 3H4 + 3H6 → 3F4 + 3F4 and energy transfer process of Tm3 +: 3F4 → Dy3 +: 6H11/2 are carried out, therefore relatively strong mid-infrared emissions at about 2900 and 4300 nm have been clearly observed.

Spectroscopic properties of Sm3 +-doped phosphate and fluorophosphate glasses of the composition (60 − x / 2) P2O5 + 15 K2O + (15 − x / 2) SrO + 10 Al2O3 + x Sm2O3 (PKSASm) and (54 − x / 2) P2O5 + 14 K2O + 10 KF + (13 − x / 2) SrO + 9 Al2O3 + x Sm2O3 (PKFSASm), where x = 0.1, 0.5, 1.0, 2.0, 4.0 and 6.0 mol%, have been investigated. The oscillator strengths and the intensity parameters (Ω2, Ω4 and Ω6) have been determined using the Judd–Oflet theory, which in turn is used to predict the radiative transition probability (AR), radiative lifetime (τR) and branching ratios for the fluorescent 4G5/2 level. The higher stimulated emission cross-sections, 12.27 × 10− 22 and 14.12 × 10− 22 cm2 have been observed for the 4G5/2 → 6H9/2 transition of PKSASm10 and PKFSASm10, respectively. The non-exponential nature of the decay curves of the 4G5/2 level increases with increase in Sm3 + ion concentration accompanied by decrease in lifetime. The non-exponential decay curves have been best fitted to the generalized Yokota–Tanimoto model indicating that the energy transfer among optically active ions is through dipole–dipole interaction.

Reducing the radiative transition’s time constant from thousands of years to a fraction of a second could benefit quantum information schemes.

It is reported that Auger-free (AF) luminescence appears with two bands at 4.5 and 6.3 eV in Rb 2 ZnCl 4 . This luminescence originates from a radiative transition of the Cl 3p valence electrons into the Zn 3d outermost-core holes. The present work is the first observation of AF luminescence due to interatomic p–d transitions in halide crystals. The appearance of two AF luminescence bands suggests the existence of two types of AF transitions following core hole creation. A largely Stokes-shifted luminescence band is also found to appear at 1.9 eV. This band has an excitation threshold at the fundamental absorption edge, and is ascribed to the radiative decay of a self-trapped exciton.

The absorption and fluorescence spectra of Dy3+-doped La3Ga5SiO14 (LGS) crystals were measured and analyzed according to the Judd–Ofelt theory. When applied, the following spectral parameters have been obtained: phenomenological intensity parameters Ωt, Ω2 = 2.64 × 10−20 cm2, Ω4 = 1.39 × 10−20 cm2 and Ω6 = 0.63 × 10−20 cm2. These intensity parameters were used to predict radiative properties that included electronic line strengths, radiative transition probabilities AJ″,J′, the radiative lifetime τrad, the fluorescence branching ratios βJ″,J′. The value of absorption section σabs(λ), and the integrated emission cross sections σem(λ) were also calculated. The emission transition 4F9/2 6H13/2 provides potential applications of LGS:Dy crystal as a laser material.

Selection rules studied here tell whether the processes,such as absorption and emission,nonradiative decay,or energy transfer happen or not.They depend on the approximation adopted.A thorough analysis of these selection rules have been given in this work and the application of these selection rules have been demonstrated through a few examples with experimental data collected from the literature.

Numerical modeling of dynamical processes in semiconductor lasers with external delayed optical feedback has been performed on the basis of the rate equations taking into account the quantum fluctuations of radiative transition rates. It has been shown that the nature of the optoelectronic signal as a function of pump current is determined by the magnitude of the optoelectronic coupling and corresponds to the behavior of the autocorrelation function of the radiation. It has been found that the radiation coherence decreases substantially with strong optical feedback. Experimental measurements confirming the theoretical results have been performed.

A theory of gain, refractive index, and linewidth enhancement factor in the quantum dots (QDs) in the nonthermal coupling (NTC) case is discussed. The ground and excited state transitions are included. Effect of parameters, like recombination time and radiative transition time, is studied. The study shows that the QDs can have zero linewidth enhancement factor. The present review covers important patents useful in this field.

Energy levels, radiative transition probabilities and autoionization rates for 1s22s22p63l'nl (n = 3–12, l ≤ n − 1) and 1s22s22p64l'nl (n = 4–7, l ≤ n − 1) states in Mg-like iron (Fe14+) are calculated by the Hartree–Fock-relativistic method (Cowan code) and the relativistic many-body perturbation theory method (RMBPT code). Autoionizing levels above three thresholds 1s22s22p63s, 1s22s22p63p and 1s22s22p63d are considered. It is found that configuration mixings [3sns + 3pnp + 3dnd] and [3snp + 3pns + 3pnd + 3dnp] play an important role for all atomic characteristics. Branching ratios relative to the first threshold and intensity factors are calculated for satellite lines, and dielectronic recombination (DR) rate coefficients are determined for the excited 444 odd-parity and 419 even-parity states. It is shown that the contribution of the highly-excited states is very important for calculation of total DR rates. Contributions from the excited 1s22s22p63l'nl states with n ≥ 12 and 1s22s22p64l'nl states with n ≥ 7 to DR rate coefficients are estimated by extrapolation of all atomic parameters. The total DR rate coefficient is derived as a function of electron temperature.

The present work aims to study the variation of Judd–Ofelt intensity parameters, radiative transition probabilities, absorption and emission cross sections with alkali content in three different Sm3+-doped mixed alkali borate glasses. Mixed alkali borate glasses in the composition 67H3BO3·xLi2CO3(32-x)Na2CO3·1Sm2O3, 67H3BO3·xLi2CO3(32-x)K2CO3·1Sm2O3 and 67H3BO3·xNa2CO3(32-x)K2CO3·1Sm2O3 with x = 8 , 12, 16, 20 and 24 mol% were prepared by quenching melts consisting of the above chemicals (850–950 °C, 1–2 h) between two brass plates. Judd–Ofelt theory is used to study the spectral properties and to calculate the radiative transition probabilities and branching ratios. The predicted radiative transition probabilities (Aed), branching ratios ( β ) and integrated absorption cross-sections ( Σ ) for certain transitions are reported. From the emission spectra, emission cross-sections ( σ P ) are obtained for the four transitions, 4G5/2→6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2 and 4G5/2→6H11/2 of Sm3+ ion in these mixed alkali borate glasses. Optical band gaps (Eopt) and absorption edges are reported for the three Sm3+-doped mixed alkali borate glasses.

Radiative transition probabilities and oscillator strengths for 164 lines arising from 5s2ns, 5s2np, 5s2nd, 5s2nf, 5s2ng and 5s5p2 configurations of Sn II have been calculated. These values were obtained in intermediate coupling (IC) and using ab initio relativistic HartreeFock (HFR) calculations. We use for the IC calculations the standard method of least square fitting of experimental energy levels by means of computer codes from Cowan. The results of calculations for radiative transition probabilities are presented and compared with the experimental result presents in the literature and with other theoretical values. These values, although in general agreement with the rare experimental data, do present some noticeable discrepancies.

Optical spectra of Dy3+:LiYF4 (Dy3+:YLF) single crystal were analyzed using Judd–Ofelt theory and discrete variational multielectron method (DVME). Oscillator strengths (OS) of transitions up to 39 000 cm−1 in the absorption spectrum, branching ratios and nonradiative transition rates were calculated; assignment of the absorption transitions was given. A good agreement between calculated and experimental values of branching ratios for transitions from quartet 4 F (3) 9/2 to the low-lying sextet levels is demonstrated. Ab initio calculations of OS were performed.

The L3 subshell x-ray intensity ratios for Ta, W, Re, Au, Hg, Tl, Pb, Th and U have been measured using an Am-241 radioisotope. Radiative transition probabilities of L3 to Mi, Ni and Oi subshells were measured by using L3 x-ray intensity ratios and Li subshell fluorescence yields. For this measurement, the new equations were used in this study. The experimental results were compared with the relativistic Hartree–Slater values of Scofield.

Multiconfiguration Dirac–Fock calculations have been carried out in the Extended Optimal Level (EOL) scheme on the energies, transition probabilities and weighted absorption oscillator strengths of intercombination lines of highly ionized argon. The calculations have been carried out in intermediate coupling with empty K shell, varying degrees of ionization in the L shell and open outer shells. The radiative transition rates have been calculated in both length and velocity gauges and an analysis on the accuracy of the orbital functions used in this work has been attempted by comparing the length form and velocity form transition rates.

A short review of theoretical and experimental studies concerning the photo‐excited florescence and Raman scattering of light for a substance in a space containing small material bodies is presented. Calculations of the radiative‐transition probability for atoms (molecules) in the vicinity of bodies with a size much smaller than the light wavelength are performed. The probabilities of the single‐photon and double‐photon transitions are shown to increase by factors of 9 and 81 in the vicinity of a nanosize sphere with dielectric constant |ɛ|\≫ 1. The probability of a radiative transition in the vicinity of the vertex of a conic needle bearing up against a plane (both with |ɛ|≫ 1) increases by factors of (λ/Rin)2 and (λ/Rin)4 for single‐photon and double‐photon transitions, respectively (Rin is the curvature radius for the needle vertex). This theoretical result is suggested as an explanation of the effect of increasing the radiation process intensity in the experiments carried out in the studies cited below.

The intensity and decay profile of the photoluminescence (PL) in glassy GeSe2 are measured as a function of temperature from 2 to 200 K. The intensity decreases exponentially in the temperature region >100 K. The complicated temperature dependence of the decay profile as well as the dependence of the intensity are explained in a unified framework by adopting a model of the luminescent sites whose thermal activation energy for the non-radiative process is distributed. We show that the intensity variation is affected by the non-radiative process while the decay life time depends almost only on the radiative transition rate.

The atomic nuclear charge (Z) dependence of the dielectronic recombination (DR) rate coefficient (α) to the O4+, Ne6+, Mg8+, P11+, Ar14+, Ca16+, V19+, Fe22+ ions as well as the auger energy (ΔE), the radiative transition probability (Ar), and the autoionization rate (Aa) for the Be-like ions is studied both in quality and quantity. For the calculation of the energy levels, Ar and Aa values, Cowan's code is employed. As for the doubly excited states, 1s23lnl' (l = s, p, d) are considered as well as 1s22pnl states. In the DR processes, at low Z, only the 1s22pnl → 1s22snl and 1s23pnl → 1s22snl processes give a significant contribution. While, at high Z, the 1s23s(or d)nl → 1s22pnl and 1s22pnl → 1s22pn'l' processes also become important. The dielectronic recombination rate coefficient to the final excited 1s22snl show weak Z-dependence, on the other hand, those to the final excited 1s22pnl states have a strong Z-dependence.

Energy levels, radiative transition probabilities and autoionization rates for CuXIX including the 1s22s22p53lnl' (n = 3 ÷ 8, l' ≤ n – 1) and 1s22s2p63lnl' (n = 3 ÷ 4, l' ≤ n – 1) doubly excited states were calculated using the multi-configurational Hartree–Fock method (Cowan code). Contributions of relativistic effects were discussed in comparison with data obtained by the multi-configurational Dirac–Fock method (YODA code). Application of the theoretical data for interpretation of experimental spectra obtained by double-electron capture in slow ion-atom collisions is discussed.

Optical absorption bands have been measured and assigned to transitions between the energy levels of Nd3+. From the optical absorption measurements and using Judd-Ofelt theory, intensity parameters ( Ω 2 , Ω 4 , Ω 6 ) have been calculated. The agreement is good between the theoretical and experimental spectral intensities. The radiative transition probabilities (A), radiative lifetimes (TR), branching ratios (β) and integrated absorption crosssections (Σ) have also been theoretically estimated and reported for certain fluorescent levels.

Optical-absorption, photoluminescence, and up-conversion luminescence were measured for Er 3 + in lead—tellurium— germanate glasses (63− x )GeO 2 · x TeO 2 · 27PbO · 10CaO with x = 0, 10, 20, 30, and 40. Each glass sample contains an extra 0.2 mol% Er 2 O 3 . Judd—Ofelt intensity parameters were determined and used to calculate the radiative transition rates and lifetimes of Er 3 + in glasses with different TeO 2 content. It has been found that the 4 S 3/2 → 4 I 15/2 radiative transition rate and the infrared (800 nm) to green (547 nm) up-conversion efficiency of Er 3 + increase with increasing TeO 2 content. Our results indicate that incorporating TeO 2 up to 40 mol% into a lead—germanate glass network increases the luminescence efficiency due to the increased refractive index and decreased maximum phonon energy of the host glass.

The optical properties of Er3+ doped 80H3BO310Na2CO310RCl (RNa, K, Li, Zn and Pb) glasses have been measured. From the optical absorption measurements and using Judd-Ofelt theory, the Judd-Ofelt parameters, Ω 2 , Ω 4 and Ω 6 , have been calculated. Measured oscillator strengths (fmeas) for various energy levels are compared with calculated values (fcal) and are in reasonable agreement. The position of the absorption edge and hence the values of optical band gaps are reported for five compositions. The predicted radiative transition probabilities (A), radiative lifetimes (τR), branching ratios (β) and integrated absorption cross sections (Σ) for the excited states 4G 11 2 , 4F 5 2 , 4F 7 2 , 4S 3 2 , 4F 9 2 , 4I 9 2 , 4I 11 2 and 4I 13 2 of Er3+ in different chloroborate glasses are reported.

A detailed investigation of radiative transition probabilities has been performed for the magnetic dipole (M1) and electric quadrupole (E2) transitions involving the metastable energy levels within the 3d5 and 3d44s configurations of Cr II. The pseudo relativistic Hartree-Fock (HFR) method, combined with an optimization of radial parameters based on the available observed energy levels, has been used for the calculations.

Absolute values for the natural halfwidths and excitation cross sections for the KrI 3d9np resonances and absolute partial widths for the spectator Auger and Auger shake decays of the KrI 3d 9 5 2 5p and the KrI 3d 9 3 2 5p resonances into KrII states have been collected and critically discussed or have been extracted from already published relative literature data. By means of photon-induced fluorescence spectroscopy a cascade population of the KrII 4s 1 4p 6 2 S 1 2 state following the excitation of the KrI 3d9np autoionizing resonances has been observed and quantified. It is ascribed to a cascade process involving a correlative radiative transition of the type 4s 2 4p 4 5p 2S+1 L J → 4s 1 4p 6 2 S 1 2 within KrII. The probability of this process is explained within a simple final-state configuration interaction estimation.

The dipole matrix element in the first order of the perturbation theory by 1/Z, Z being the nuclear charge, has been calculated for all the possible radiative transitions (nl)k(n'l')k'Φ – (nl)k+1(n'l')k' - 1Φ with the electronic configuration Φ = 1sk12sk22pk33sk43pk53dk64sk74pk84dk94fk10, nl and n'l' belonging to any subshell of this configuration. The Kα x-ray emission rates for atoms with Z = 10–36 have been calculated and compared with other theoretical results. The contribution of the first order of the dipole matrix element to the radiative transition probability has also been studied.

Energy levels, radiative transition probabilities and autionization rates for C II including 1s22l2l'nl" (n = 2–6, l" ≤ (n − 1)] states were calculated by using the multi-configurational Hartree-Fock (Cowan code) method. Autoionizing levels above three thresholds: 1s22s2(1S), 1s22s2p(3P), 1s22s2p(1P) were considered. Branching ratios relative to the first threshold and intensity factors were calculated for satellite lines and dielectronic recombination rate coefficients for C II ions.

Absolute values for the energies, natural halfwidths and excitation cross sections for the Kr I resonances and absolute partial widths for the spectator Auger, participator Auger and Auger shake decays of the Kr I and the Kr I resonances into Kr II states have been collected and critically discussed or have been extracted from already published relative literature data. By means of photon-induced fluorescence spectroscopy a cascade population of the Kr II state following the excitation of the Kr I autoionizing resonances was observed and quantified. It is ascribed to a cascade process involving a correlative radiative transition of the type within Kr II. The probability of this process is explained within a very simple final-state configuration interaction calculation.

K - MM radiative Auger (RA) spectra have been measured for several compounds containing K and Ca. Transition energies are evaluated by the use of various sources: the DV- calculation, term values from optical spectroscopy, and L - MM Auger energies. It is shown that the DV- calculation is very useful in the understanding of RA spectra; calculated transition energies agree well with observed ones as well as those estimated from optical data, giving an unambiguous assignment for the observed spectra. On the other hand, transition energies evaluated from L - MM Auger energies sometimes disagree with others. Possible reasons for the discrepancy are discussed.

The electronic structure of [CsCln] molecular cluster and possible radiative transitions between crystal valence band and impurity core states are calculated with self-consistent field Xα scattering wave method. Correlation of experimental and theoretical data confirms the local cluster-type nature of the radiative core-valence transitions.

The K partial and total fluorescence yields of lanthanum, in the presence of a spectator hole in one of the three L subshells, are discussed. It is shown that the K partial fluorescence yield can change considerably in the presence of the L spectator hole. Dirac-Fock wavefunctions have been used for the calculation of the dipole radiative transition rates. A statistical weighting semi-empirical formula for the calculation of the relative K radiative rates is proposed, which permits the evaluation of the relative K radiative rates in the presence of spectator hole(s), for middle and high Z elements, with high accuracy. Finally the lifetime of a K hole in a KL hole atomic configuration is calculated and is compared with the lifetime of a K hole in a single K hole atomic configuration. It is shown that the lifetime of the K hole is affected by the presence of the L hole and it depends on the particular L subshell.

The radiative transitions between valence band and outermost core band were studied to determine the density of the electron states and other energy-band parameters of wide-gap CsCaCl 3 , CsMgCl 3 , CsMgF 3 and RbCaF 3 crystals. With this method the resolution of structural detail in the energy bands of those crystals exceeds the one obtained by XPS.

The steady-state and time-resolved luminescence of CuBr quantum dots of different growth processes and in the wide range of sizes between R/aB≈ 1 to 6 has been analysed. A radiative transition energetically lower than the exciton luminescence has been observed and attributed to the confined biexciton state. The increasing biexciton binding energy with increasing confinement has been confirmed, in agreement with theory and experimental results reported for CuCl.

In this paper, the optical absorption and emission spectra of Sm3+ ions in 5BiO1.5-20WO3-75TeO2 glasses (0.2, 0.5, 1.0, 2.0 and 3.0 mol% of Sm3+) are presented. These glasses have been developed very recently and are found to exhibit excellent third-order nonlinear properties. A Judd-Ofelt analysis has been performed in order to calculate various optical parameters such as Judd-Ofelt parameters, radiative transition probabilities, and stimulated emission cross-section. According to the computed Judd-Ofelt parameters, the symmetry of the sites occupied by the Sm3+ ions increased as the amount of Sm2O3 was increased, and the covalency decreased above 1.0 mol%. The results of the stimulated emission cross-section revealed that the 4G5/2 6H7/2 transition of 1.0 mol% Sm3+ in 5BiO1.5-20WO3-75TeO2 glasses could be promising for lasing action. Emission spectrum of 1.0 mol% Sm2O3-doped 5BiO1.5-20WO3-75TeO2 glass. Judd-Ofelt parameters (Ωλ) and peak emission stimulated cross-section σ (λp) are shown in the figure. The 4G5/2 6H7/2 transition is promising for lasing action. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Crystallized aGe:H/aSiNX:H multiquantum-well (MQW) structures were prepared by a computer controlled plasma enhanced chemical vapor deposition method and then crystallized by Ar+ laser annealing technique. The layered structures and the crystallinity of the samples were determined by means of X-ray diffraction (XRD) spectroscopy. The crystallized samples showed a radiative transition with visible light as the Ge well layer thickness was less than 4 nm. This may preliminary be explained by the quantum confinement of electrons and holes.

The luminescence of LiGa5O8:Mn4+ was observed with measurements of decay times and intensities for different temperatures. The experimental results were analysed taking into account purely radiative, vibronic and radiationless transitions. It is shown that the nonradiative process involves 46 phonons, each with an energy of 304 cm−1.

A novel oxyfluoromolybddate, CdMoO3F2, with CuWO3F2-type structure has been prepared. The temperature dependence of the luminescence intensity and lifetime has been determined and compared with that of the cadmium molybdate, CdMoO4. The lower position of the emittinfg state, consequence of the octahedral coordination, and smaller radiative transition rate result in a higher temperature quenching of the CdMoO3F2 emission.

Optical studies of type-II ZnTe/Cd 1− x Mn x Se superlattices show two types of interband transitions: (i) radiative type-II transitions between electrons confined in the Cd 1− x Mn x Se and holes confined in the ZnTe layers, and (ii) strongly absorptive type-I transitions associated with the formation of novel excitons involving confined electrons and above-barrier holes, both of which are localized in the Cd 1− x Mn x Se layers. The spatial localization of the states participating in both types of transitions is identified by magneto-optical spectroscopy.

Time‐resolved photoluminescence has been used to study the decay of photoexcited carriers in bulk InSb at 2 K. The recombination occurs as a two step process exhibiting a fast and a slow decay. The fast decay, corresponding to band‐to‐band recombination, occurs with a time constant of the order of 60 nsec and is accompanied by time‐resolved band gap renormalization. The slow process, identified in the band‐to‐acceptor photoluminescence, occurs with a time constant of 3.8 μsec. We show that this is in excellent agreement with the theoretical value of the band‐to‐acceptor radiative transition rate. These results help reconcile discrepancies that have long existed between conventional photoluminescence measurements and time‐resolved photoconductivity measurements.

A Hanle experiment has been used to determine the following radiative lifetimes (in nsec) of rubidium: ${\mathrm{\ensuremath{\tau}}}_{6\mathit{D}3/2}$=298\ifmmode\pm\else\textpm\fi{}8, ${\mathrm{\ensuremath{\tau}}}_{7\mathit{D}3/2}$=345\ifmmode\pm\else\textpm\fi{}9, ${\mathrm{\ensuremath{\tau}}}_{8\mathit{D}3/2}$=586\ifmmode\pm\else\textpm\fi{}15, and ${\mathrm{\ensuremath{\tau}}}_{9\mathit{D}3/2}$=638\ifmmode\pm\else\textpm\fi{}17. These data were taken at a temperature of 293 K and are not corrected for effects due to blackbody radiation. The effect of the hyperfine interaction on the Hanle signal is discussed in detail for an excited state of arbitrary angular momentum.

Glasses with composition (in mol %), 32 ZnF 2 , 28 CdF 2 , 20 BaF 2 , 11 LiF, 5 AlF 3 , 4 LaF 3 have been prepared and doped with some 4f ions (Ho 3+ , Tm 3+ , Er 3+ ). The energy levels and oscillator strengths of the electronic transitions have been obtained. Using the Judd-Ofelt theory, the radiative transition probabilities between the different levels were calculated. We have measured the emission bands and lifetimes and determined the non-radiative transition rates, the luminescence efficiencies and the emission cross-sections of some “laser transitions”. The optical properties of this new material are slightly improved with respect to those of the fluorozirconate glasses.