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The combined relativistic energy approach and relativistic many-body perturbation theory with the zeroth order Dirac-Kohn-Sham one-particle approximation are used for estimating the energies and the E1 radiative transitions amplitudes (oscillator strengths) for the low-excited states of the francium. The comparison with available theoretical and experimental (compilated) data is performed. The important point is linked with an accurate accounting for the complex exchange-correlation (polarization) effect contributions and using the optimized one-quasiparticle representation in the relativistic many-body perturbation theory zeroth order that significantly provides a physically reasonable agreement between theory and precise experiment.

We revisited the mass spectra of the Ξcc++ baryon with positive and negative parity states using Hypercentral Constituent Quark Model Scheme with Coloumb plus screened potential. The ground state of the baryon has been determined by the LHCb experiment, and the anticipated excited state masses of the baryon have been compared with several theoretical methodologies. The transition magnetic moments of all heavy baryons Ξcc++, Ξcc+, Ωcc+, Ξbb0, Ξbb−, Ωbb−, Ξbc+, Ξbc0, Ωbc0 are also calculated and their values are −1.013 μN, 1.048 μN, 0.961 μN, −1.69 μN, 0.73 μN, 0.48 μN, −1.39 μN, 0.94 μN and 0.710 μN, respectively.

We studied the role of intrinsic defects of matrix and Bi dopant in the formation of optical properties and energy structure of CaMoO 4 :Bi ceramic. Non-elementary luminescence was detected in a pure CaMoO 4 matrix due to radiative transitions in intrinsic vacancy-type defects, which are associated with non-stoichiometry in calcium. The experiment showed that Bi ions act as quenchers of luminescence. © Published under licence by IOP Publishing Ltd. The work has been funded by the Ministry of (Governmenttask№3.1485.2017/4.6).

Luminescence lifetime based temperature sensing has an intrinsic immunity to the influence of external conditions, and dual mode thermometry is highly accurate due to its “self-calibration” merit. To develop thermometry with both features, we investigated the phase and microstructural evolution of Cr3+-doped calcium-fluorosilicate glass and glass-ceramics, which revealed different luminescent behavior relating to the different Cr3+ sites in the materials. From the photoluminescence (PL) spectra, the emission at 717 nm was derived from the O-coordinated octahedral sites, while the 1 μm super-broad emission was assigned to the F-coordinated octahedral sites. After an annealing treatment, cubic CaF2 nanocrystals were homogeneously precipitated in the glass-ceramics; thus, both the O-coordination in the residual glass phase and F-coordination in the CaF2 crystalline phase were strengthened. This led to the enhancement of both the emissions at 717 nm and 1 μm. The O-coordinated sites were relatively strong-field sites in which the fluorescence of Cr3+ originated from the radiative transitions of the two thermally coupled energy levels, 2E and 4T2, while the F-coordinated sites were relatively weak-field sites. Hence, the Cr3+ exhibits only one excited state 4T2, which is inactivated by radiative transitions and non-radiative transitions from the thermal quench. Based on the obtained results, the maximum relative temperature sensitivity coefficients are 0.76% K−1 at 498 K for the 717 nm emission and 0.47% K−1 at 351 K for the 1 μm emission. This provides the possibility of developing a dual mode temperature sensor with high precision only using a single material.

Lattice QCD calculations of radiative transitions between hadrons have in the past been limited to processes of hadrons stable under the strong interaction. Recently developed methods for 1 → 2 transition matrix elements in a finite volume now enable the determination of radiative decay rates of strongly unstable particles. Our lattice QCD study focuses on the process ππ → πγ∗, where the ρ meson is present as an enhancement in the cross-section. We use 2+1 flavors of clover fermions at a pion mass of approximately 320 MeV and a lattice size of approximately 3.6 fm. The required 2-point and 3-point correlation functions are constructed from a set of forward, sequential and stochastic light quark propagators. In addition to determining the ρ meson resonance parameters via the Lüscher method, the scattering phase shift is used in conjunction with the 1 → 2 transition matrix element formalism of Briceño, Hansen and Walker-Loud [1] to compute the ππ → πγ∗ amplitude at several values of the momentum transfer and pp invariant mass. © Copyright owned by the author(s). Part F128557 Sponsors: Conference code: 128557

Radiative transitions between the three lowest-lying electronic states of molecular oxygen have long provided a model to study how collision-dependent perturbations influence forbidden processes. In an isolated oxygen molecule, transitions between the O-2(X-3 Sigma(-)(g)), O-2(a(1)Delta(g), and O-2(b(1)Sigma(+)(g)) states are forbidden as electric-dipole processes. For oxygen dissolved in organic solvents, the probabilities of radiative transitions between these states increase appreciably. Attempts to interpret solvent-dependent changes in the radiative rate constants have principally relied on O-2(b(1)Sigma(+)(g)) and O-2(a(1)Delta(g)) emission experiments. However, the dominant nonradiative deactivation channels of O-2(b(1)Sigma(+)(g)) make it difficult to quantify solvent effects on the O-2(b(1)Sigma(+)(g)) -> O-2(a(1)Delta(g)) radiative process. Thus, an appreciable amount of important information has heretofore not been available. In the present study, we examined the effect of 17 common organic solvents on the O-2(a(1)Delta(g)) -> O-2(b(1)Sigma(+)(g)) absorption transition at similar to 5200 cm(-1) (i.e., similar to 1925 nm). The solvent-dependent absorption coefficients at the band maximum, em, range from 5 to 50 M-1 cm(-1) and correlate reasonably well with the solvent refractive index; emax is largest in solvents with the largest refractive index. This observation is consistent with a model in which oxygen is perturbed to a greater extent by solvents with a large electronic polarizability. Through the Strickler-Berg equation, we also used these absorption data to obtain the radiative rate constant for the O-2(b(1)Sigma(+)(g)) -> O-2(a(1)Delta(g)) transition, and the results are consistent with a model in which the O-2(a(1)Delta(g)) -> O-2(X-3 Sigma(-)(g)) transition is said to steal intensity from the O-2(b(1)Sigma(+)(g)) -> O-2(a(1)Delta(g)) transition.

Eu+3 was incorporated into the lattice of a lead-free ferroelectric Na1/2Bi1/2TiO3 (NBT) as per the nominal formula Na0.5Bi0.5-xEuxTiO3. This system was investigated with regard to the Eu+3 photoluminescence (PL) and structural behaviour as a function of composition and electric field. Electric field was found to irreversibly change the features in the PL spectra and also in the x-ray diffraction patterns below the critical composition x = 0.025. Detailed analysis revealed that below the critical composition, electric field irreversibly suppresses the structural heterogeneity inherent of the host matrix NBT and brings about a long range ferroelectric state with rhombohedral (R3c) distortion. It is shown that the structural disorder on the nano-scale opens a new channel for radiative transition which manifests as a new emission line branching off from the main 5D0?7F0 line along with a concomitant change in the relative intensity of the other crystal field induced Stark lines with different J values. The study suggests that Eu+3 luminescence can be used to probe the relative degree of field induced structural ordering in relaxor ferroelectrics and also in high performance piezoelectric alloys where electric field couples very strongly with the lattice and structural degrees of freedom. � 2015 AIP Publishing LLC.

We experimentally investigated the effect of oscillator strength (radiative transition diagonality) on the performance of resonant phonon-based terahertz quantum cascade lasers that have been optimized using a simplified density matrix formalism. Our results show that the maximum lasing temperature (Tmax) is roughly independent of laser transition diagonality within the lasing frequency range of the devices under test (3.2‐3.7THz) when cavity loss is kept low. Furthermore, the threshold current can be lowered by employing more diagonal transition designs, which can effectively suppress parasitic leakage caused by intermediate resonance between the injection and the downstream extraction levels. Nevertheless, the current carrying capacity through the designed lasing channel in more diagonal designs may sacrifice even more, leading to electrical instability and, potentially, complete inhibition of the device’s lasing operation. We propose a hypothesis based on electric-field domain formation and competition/switching of different current-carrying channels to explain observed electrical instability in devices with lower oscillator strengths. The study indicates that not only should designers maximize Tmax during device optimization but also they should always consider the risk of electrical instability in device operation. V C 2013 American

In this work we use the multiconfiguration Dirac-Fock method to calculate the transition probabilities for all possible decay channels, radiative and radiationless, of a K shell vacancy in Zn, Cd and Hg atoms. The obtained transition probabilities are then used to calculate the corresponding fluorescence yields which are compared to existing theoretical, semi-empirical and experimental results.

The database ADAMANT of atomic parameters for the simulation of the electromagnetic radiation from plasma is established (www.adamant.tfai.vu.lt). The energy levels, radiative and autoionization transition probabilities, electron-impact excitation and ionization as well as dielectronic recombination rates for atoms and ions are constantly added to the database.

Radioch; Absorption and emission as well as emission decay times of Ho3+ ions embedded in LaAlO3 single crystal were measured. The experimental results were analysed in the frame of the Judd–Ofelt theory. Energy levels, oscillator strengths and probabilities of radiative transitions were determined. The results indicate on nonradiative transitions due to cross-relaxation down and up-conversions processes.

Radiative transitions K to L-2, L-3 subshell and M shell were measured using the K X-ray spectrum for 21 elements in the atomic range 41 less than or equal to Z less than or equal to 68. The targets were irradiated with T photons at 59.5 keV from Am-241 radioisotope source. The theoretical values were calculated using the radiative and nonradiative transition rates of these elements. It was observed that present values agree with previous theoretical results. (C) 2002 Elsevier Science Ltd. All rights reserved.

A comprehensive set of theoretical Coster-Kronig and fluorescence yields are presented for atomic numbers 18 less than or equal to Z less than or equal to 100. These quantities are based on ab initio relativistic calculations. Agreement with experimental values is fair for omega (1) and generally good for omega (2), omega (3) (Z greater than or equal to 54) [1]. Therefore, atomic L shell fluorescence (omega (1), omega (2), omega (3)) and Auger yields (a(1), a(2) and a(3)) for some elements in the atomic number range 59 less than or equal to Z less than or equal to 85 were determined. These selected measured semi-empirical values were also fitted by least squares to polynomials in the Z of the form Sigma (n)a(n)Z(n) and compared with theoretical and with earlier fitted values. (C) 2000 Elsevier Science B.V. All rights reserved.

Photoluminescence (PL) spectra of TlGaS2 layered single crystals were studied in the wavelength region 500-860 nm and in the temperature range 9.5-293 K. We observed a total of three PL bands centered at 568 nm (2.183 eV, A-band), 718 nm (1.727 eV, B-band) and 780 nm (1.590 eV, C-band) at various temperatures. We have also studied the variations of the A- and B-band intensities vs excitation laser density in the range from 7 × 10-2 to 9 W cm-2. The A- and B-bands were found to be due to radiative transitions from the deep donor levels located at 0.362 and 0.738 eV below the bottom of the conduction band to the shallow acceptor levels at 0.005 and 0.085 eV located above the top of the valence band, respectively. The proposed energy-level diagram permits us to interpret the recombination processes in TlGaS2 layered single crystals. © 1997 Elsevier Science Ltd.