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Abstract: The low-lying electronic states (X 2Π, a 4Π, b 4Σ−, B 2Π, 12Φ, A 2Δ and B′2Σ+) of the NS molecule are computed at the AV5Z/CASSCF/MRCI+Q+DK level of theory. The potential energy curves are presented for these states; the corresponding spectroscopic constants are reported. Electronic transition moment functions, Einstein coefficients, Franck–Condon factors and radiative lifetimes for the B 2Π–X 2Π, B′2Σ+–X 2Π and A 2Δ–X 2Π system have been calculated. The F–C factors of the B 2Π are in good agreement with the corresponding RKR data. The B′2Σ+ state possesses a barrier in the potential energy curve, located at about 2.16Å. The height of the barrier is predicted to be 7890cm−1. [Copyright &y& Elsevier]

Abstract: The lowest-lying electronic states of LiAs are studied by the CASSCF/MRCI/ aV5Z(-PP) ab initio approach. We report full potential energy curves (PECs) as well as the associated spectroscopic constants, and dipole moment functions for the bound states. The transition dipole moment and transition probabilities associated with A3Π–X3Σ− band system are discussed and the radiative lifetimes of various vibrational levels of the A3Π state are also estimated. Spin–orbit effects were also taken into account leading to some distinctive properties in the PEC’s, mainly because of the presence of repulsive state a 5Σ− that also correlates with the first channel. Similarities and differences with the systems, AsH, LiN and LiP are also discussed. [Copyright &y& Elsevier]

The structure and spectroscopic properties of the ground and the lowest excited electronic states of the alkali hydride cation NaH+ have been investigated using an ab initio approach. In this approach, a nonempirical pseudopotential for the Na+ core has been used and a core-core and a core-valence correlation corrections have been added. The adiabatic potential energy curves and the molecular spectroscopic constants for numerous electronic states of 2Σ+, 2Π, and 2Δ symmetries, dissociating up to Na (4 d) + H+ and Na+ + H (3 d), have been calculated. As no experimental data are available, we discuss our results by comparing with the available theoretical calculations. A satisfying agreement has been found for the ground state with previous works. However, a clear disagreement between this study and the model potential work of Magnier (Magnier, J. Phys. Chem. A 2005, 109, 5411) has been observed for several excited states. Numerous avoided crossings between electronic states of 2Σ+ and 2Π symmetries have been found and analysed. They are related to the interaction between the potential energy curves and to the charge transfer process between the two ionic systems Na+H and NaH+. Furthermore, we provide an extensive set of data concerning the transition dipole moments from X2Σ+ and the 22Σ+ states to higher excited states of 2Σ+ and 2Π symmetries. Finally, the adiabatic potential energy curves of the ground (X2Σ+) and the first (22Σ+) excited states and the transition dipole moments between these states are used to evaluate the radiative lifetimes for the vibrational levels of the 22∑+ state for the first time. In addition to the bound-bound contribution, the bound-free term has been evaluated and added to the total radiative lifetime. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: High-level CASSCF/MRCI calculations with a quintuple-zeta quality basis set are reported characterizing a manifold of electronic states of the BeCl correlating with the two lowest-lying dissociation channels. A very reliable picture of the potential energy curves showing regions of both avoided and curve crossings over a wide range of internuclear distances and the associated spectroscopic parameters provide new data that can help better rationalize the transitions so far observed. Our calculations suggest that the assignments and data for the band system C 2Σ+−X 2Σ+ warrant new experimental studies. In fact we show that the C 2Σ+ state (B 2Σ+ in the experimental paper) has a double minimum. Also spin–orbit effects on the A 2Π state are shown to be relatively small. For the first time, transition moment functions for the major transitions are reported in the literature and used to estimate transition probabilities and radiative lifetimes. [Copyright &y& Elsevier]

Abstract: TeO2–CdF2–WO3 glasses with various compositions and Er3+ concentrations were prepared by conventional melting method. Their optical properties were studied by measuring the absorption, luminescence spectra and the decay patterns at room temperature. From the optical absorption spectra the Judd-Ofelt parameters (Ω t ), transition probabilities, branching ratios of various transitions, and radiative lifetimes were calculated. The absorption and emission cross-section spectra of the 4I15/2 to 4I13/2 transition of erbium were determined. Emission quantum efficiencies and the average critical distance R 0 which provides a measure for the strength of cross relaxation were determined. [Copyright &y& Elsevier]

We calculate multireference configuration-interaction wavefunctions and the potential-energy curves for the $ {B^3}\Sigma_u^{-} $ and $ {X^3}\Sigma_g^{-} $ states of the collision-free S molecule and the T-shape collision complex S-He using cc-pVQZ basis sets. We obtain the transition dipole moments of the $ {{\text{S}}_2}\left( {{B^3}\Sigma_u^{-} \to {X^3}\Sigma_g^{-} } \right) $ and the Franck-Condon factors between the vibrational levels of this two states. We evaluate the radiative lifetimes of $ {{\text{S}}_2}\left( {{B^3}\Sigma_u^{-} \left( {{\upsilon^{\prime}} = 0 - 9} \right)} \right) $ levels of the collision complex and the collision-free molecule and compare them with the experiments. The collision provides little change in the radiative lifetimes of $ {{\text{S}}_2}\left( {{B^3}\Sigma_u^{-} \left( {{\upsilon^{\prime}} = 0 - 9} \right)} \right) $ according to the previous calculations. We obtain excellent agreement between the theoretical results and the experiments. The data calculated are very useful in the study of the microwave-driven high-pressure sulfur lamp and an S laser pumped by a transverse fast discharge. [ABSTRACT FROM AUTHOR]

Abstract: The main spectroscopic parameters (intensity parameters, radiative life times, branching ratios, quantum efficiency and emission cross-section of the 4F3/2→4I9/2 transition) of the 38PbO-62SiO2 glass doped with Nd3+ are evaluated using the standard Judd–Ofelt theory. Remarkably low values of the intensity parameters Ω2,4,6 are explained by structural modifications of the Nd3+ surroundings caused by presence of the Pb ions. [ABSTRACT FROM AUTHOR]

The electronic excitation transitions of carbazole-based oligomers, (Cz-co-Cz) N, (Cz-co-Fl) N and (Cz-co-Th) N ( N = 2–4) were investigated using density functional theory (DFT) and time-dependent (TD) DFT methods. Our results show that the calculated ground state geometries favor a more aromatic, planer structure, while the electronically excited geometries favor a quinoidic type structure. Absorption and fluorescence energies have been obtained from TD-B3LYP/SVP calculations performed on the S1 optimized geometries and are in excellent agreement with experimental data. The experimental fluorescence excitation energies for (Cz-co-Cz)4, (Cz-co-Fl)4 and (Cz-co-Th)4 (2.76, 2.63, and 2.25 eV, respectively) correspond closely with the predicted S1 transitions (2.84, 3.91 and 2.43 eV, respectively). We also report the predicted radiative lifetimes 0.52, 0.47, and 0.99 ns for (Cz-co-Cz) N, (Cz-co-Fl) N and (Cz-co-Th) N, discuss the origin of the small stoke shift of the carbazole based oligomers and the magnitude of bathochromic shifts. We conclude by discussing the benefits of theoretical calculations, which can provide critical structural and electronic understanding of excitation–relaxation phenomena that can be exploited in design of novel optical materials. [ABSTRACT FROM AUTHOR]

[Display omitted] The influence of spin-orbit coupling on the cooling of NH molecular laser is investigated based on the ab initio theory. The potential energy curves (PECs) and spectral constants for four Λ - S states ( X 3 Σ - , a 1 Δ , b 1 Σ + and A 3 Π) and eight Ω states (X 3 Σ 0 + , 1 - , a 1 Δ 2 , b 1 Σ 0 + + and A 3 Π 0 - , 0 + , 1 , 2 ) of NH molecule are obtained by the multi-reference configuration interaction (MRCI) plus Davidson correction. The spectroscopic constants (R e , ω e , ω e χ e , B e , D e) are obtained by solving the one dimensional radial Schrödinger equation, and the results are almost the same as the previously reported data. In addition, the transition dipole moment, permanent dipole moment, Franck-Condon factors, and radiative lifetime of NH molecule are also acquired. Also, the effects of the intermediate state on the X 3 Σ 0 + - ↔ A 3 Π 1 , X 3 Σ 1 - ↔ A 3 Π 0 + and X 3 Σ 1 - ↔ A 3 Π 0 - transitions are considered. The feasible laser cooling schemes using a single laser are formulated. In the proposed cooling scheme, there wavelengths for the X 3 Σ 0 + - ↔ A 3 Π 1 are used, the main pump lasers are λ 00 = 335.74 nm. The feasible transition is based on this. It is found that spin-orbit coupling has a significant effect on potential energy curves, permanent dipole moments, transition dipole moments and vibration energy levels. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fock-space relativistic coupled cluster calculations. • Potential energy curves. • Molecular spectroscopic constants. • Radiative properties. • Laser cooling scheme. The potential energy curves of the ground and five low-lying excited terms of the RaF molecule are calculated using the Fock-space relativistic coupled theory. The electronic term energies, equilibrium internuclear distances, transition and permanent dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck–Condon factors, and radiative lifetimes are predicted. The calculated spectroscopic constants are in good agreement with the available theoretical and experimental data. The scheme for the direct laser cooling involving the first excited A 2П 1/2 state is proposed. The data obtained in this study suggests the A 2П 1/2 → X 2Σ+ channel in the RaF molecule is the almost ideal case for direct laser cooling. It is quite possible that the effective cooling scheme for the RaF molecule can be realized using only one pump laser. [ABSTRACT FROM AUTHOR]

The ab initio quasirelativistic approach developed specifically for the calculation of spectral parameters of highly charged ions was used to derive transition data for the Ru-like tungsten ion W 30 +. The configuration interaction method was applied to include electron correlation effects. The relativistic effects were taken into account in the Breit–Pauli approximation. The level energies, radiative lifetimes τ , Landé g -factors were determined for the ground configuration 4p64d8 and two excited configurations 4p54d9 and 4p64d74f. The radiative transition wavelengths λ and emission transition probabilities A for the electric dipole, electric quadrupole, electric octupole, magnetic dipole, and magnetic quadrupole transitions among the levels of these configurations were generated. [ABSTRACT FROM AUTHOR]

• The accurate electronic structures of HgI are calculated with MRCI+Q method. • The spin-orbit coupling effect is included in the calculation. • Spectroscopic constants for bound states of HgI are obtained. • Radiative lifetimes of B2Σ+ 1/2 , C2Π 1/2 and D2Π 3/2 of HgI are determined. • The perturbations on the vibrational levels of the C2Π state are analyzed. The multireference configuration interaction (MRCI) method with inclusion of Davidson correction (+ Q) and spin-orbit coupling (SOC) effects is adopted to compute the electronic structures of the low-lying states of HgI. The potential energy curves (PECs) of 14 Λ-S states correlated with the first and second dissociation limits together with 30 low-lying Ω states are calculated. The spectroscopic constants of bound states are obtained, which agree well with the available experimental values. With the assistance of calculated SOC matrix elements, the perturbations on the vibrational levels of the C2Π caused by nearby state are analyzed. Finally, the spontaneous radiative lifetimes of bound states are evaluated, which are in consistence with existing measurements. [Display omitted] [ABSTRACT FROM AUTHOR]

• A semi-empirical parametrization method for forbidden transition on an example of analysis of experimental data for Sc II is presented. • Perfect agreement of calculated and experimental values of transition probabilities and radiative lifetimes is achieved. • The obtained results are compared with other calculated data available. • The predicted values of radiative parameters for all Sc II metastable levels are presented. We present a semi-empirical parametrization method for calculation of spontaneous radiative decay rates of forbidden transitions on an example of analysis of experimental data for Sc II. The values of transition probabilities and radiative lifetimes of metastable levels are in perfect agreement with experimental ones. The obtained results are compared with other calculated data available. The predicted values of radiative parameters for all Sc II metastable levels are presented. [ABSTRACT FROM AUTHOR]

• Fock-space relativistic coupled cluster calculations. • Potential energy curves. • Molecular spectroscopic constants. • Radiative properties. • Laser cooling scheme. The potential energy curves of the ground and five low-lying excited states of the RaBr molecule are calculated using the Fock-space relativistic coupled cluster theory for the first time. A number of properties such as the electronic term energies, equilibrium internuclear distances, transition and permanent dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck–Condon factors, and radiative lifetimes are predicted. The results of this study show that RaBr molecules can be used for the direct laser cooling. The comparison to the previous theoretical studies of the RaF and RaCl molecules is also provided. [Display omitted] [ABSTRACT FROM AUTHOR]

• Semi-empirical parametrization of the radiative parameters for atomic manganese was performed. • Radiative lifetimes for excited levels were determined. • Based on transition probabilities, possible clock transitions in the manganese atom were proposed. • For the considered clock transitions suitable laser cooling schemes were proposed and discussed. In this article the values of the radiative parameters for atomic manganese were determined by means of a semi-empirical method. The eigenvector amplitudes determined in our previously published research were adopted. The calculated values of oscillator strengths and lifetimes are, in the majority of cases, in good agreement with experimental data. The results were also compared with available theoretical calculations. On the basis of the calculations performed, as well as related available literature data on transition probabilities and excited levels' lifetimes, possible clock transitions in neutral 55 Mn were proposed; three candidate transitions were considered in this context. Possibilities of laser cooling of manganese atoms were also discussed. [ABSTRACT FROM AUTHOR]

We theoretically investigate the interaction between a single molecule and a metallic nanoparticle (MNP). We develop a general quantum mechanical description for the calculation of the enhancement of radiative and nonradiative decay channels for a molecule situated in the near-field regime of the MNP. Using a boundary element method approach, we compute the scattering rates for several nanoparticle shapes. We also introduce an eigenmode expansion and quantization scheme for the surface plasmons, which allows us to analyze the scattering processes in simple physical terms. An intuitive explanation is given for the large quantum yield of quasi-1-D and quasi-2-D nanostructures. Finally, we briefly discuss resonant Forster energy transfer in presence of MNPs. [ABSTRACT FROM PUBLISHER]

We have examined the optical and photoluminescence (PL) properties of Er3+-doped GeGaS glasses of near-stoichiometric composition Ge28Ga6.2S65.3:Er0.5. We have also used powdered samples of various mean sizes (L) to examine the dependence of the 1.54 -mum PL emission spectrum and the PL decay time on the average sample size. Optical absorption spectra of Er3+ ions arising from transitions between different energy manifolds, such as 4 I15 /2 -4 I13/2,4 I15 /2 -4 I11 /2 , etc., have been used to extract Omega2, Omega4, and Omega6 values using the Judd-Ofelt analysis and a Judd-Ofelt radiative lifetime TJO = 2.6 ms for the 4 I13 / 2 -4 I15 / 2 transition. The PL emission spectra and the decay time have been found to depend on the mean sample size. The spectra are broader and the decay times are longer for larger sample sizes, due to photon trapping occurring in the sample. The extrapolated decay time to zero particle size yields a decay time that matches the Judd-Ofelt radiative lifetime almost perfectly, and confirms the argument that the true PL lifetime needs to be measured in fine powders to avoid reabsorption effects. We have estimated the maximum emission cross section as 15.5 X 10-21 cm2. [ABSTRACT FROM PUBLISHER]

Abstract: The photoluminescence (PL) at low temperature of three delta-doped AlGaAs/GaAs heterostructures is investigated under continuous and pulsed excitations. The PL under continuous excitations allows the identification of the trapping centres and probes the carrier''s transfer to the GaAs channel. The time-resolved photoluminescence (TRPL) inquires about carrier dynamics and gives radiative lifetimes of different levels. The DX level shows two time constants of the intensity decay relating the splitting of the valence band under impurity strains which reduce the crystal symmetry. The two time constants evolve with temperature and exhibit an increase near T=50K. [Copyright &y& Elsevier]

Photodynamic therapy (PDT) is an effective treatment option for various types of invasive tumors. The efficacy of PDT treatment depends strongly on selective cell uptake and selective excitation of the tumor. The characterization of fluorescence lifetimes of photosensitizers localized inside living cells may provide the basis for further investigation of in vivo PDT dosage measurements using time-domain spectroscopy and imaging. In this communication, we investigated the fluorescence lifetime of localized Photofrin and delta-aminolevulinic acid (ALA) induced protoporphyrin IX (PpIX) in living MAT-LyLu (MLL) rat prostate adenocarcinoma cells. The MLL cells were incubated with the photosensitizers, and then treated with light under well-oxygenated conditions using a two-photon fluorescence lifetime imaging microscope (FLIM). Fluorescence lifetime images of these cells were recorded with average lifetimes of 5.5 plusmn 1.2 ns for Photofrin and 6.3 plusmn 1.2 ns for ALA-induced PpIX. When localized in cells, the lifetimes of both photosensitizers were found to be significantly shorter than those measured in organic solutions. The result for PpIX is consistent with literature values, while the lifetime of Photofrin is shorter than what has been reported. These results suggest that time-domain methods measuring photosensitizer lifetime changes may be good candidates for in vivo PDT dosage monitoring. [ABSTRACT FROM PUBLISHER]

Radiative transition probabilities (Einstein A coefficients), Franck-Condon factors, and radiative lifetimes have been determined for the X3Π, 3Σ-, a1Σ+, 1Π, c1 Δ, and A3Σ+ states of the CO2+ dication using ab initio potential energy, spin-orbit coupling, electric dipole and electronic transition moment functions, and the standard complex-scaling method. The calculated radiative lifetimes of the upper electronic states of the spin-allowed A3Σ+–X3Π and b1Π–a1Σ+ transitions are generally longer than their predissociating lifetimes, explaining thus the failure of the attempts made so far to observe CO2+ in the optical spectral region in a convincing fashion. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [ABSTRACT FROM AUTHOR]

Radiative transition probabilities (Einstein A coefficients), Franck-Condon factors, and radiative lifetimes have been determined for the X3Π, 3Σ-, a1Σ+, 1Π, c1 Δ, and A3Σ+ states of the CO2+ dication using ab initio potential energy, spin-orbit coupling, electric dipole and electronic transition moment functions, and the standard complex-scaling method. The calculated radiative lifetimes of the upper electronic states of the spin-allowed A3Σ+–X3Π and b1Π–a1Σ+ transitions are generally longer than their predissociating lifetimes, explaining thus the failure of the attempts made so far to observe CO2+ in the optical spectral region in a convincing fashion. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [ABSTRACT FROM AUTHOR]

Forster resonance energy transfer (FRET) between a donor and an acceptor dye molecule is a common method to study the distances between single molecules in living cells in the nanometer range. Quantitative distance measurements are difficult to obtain in spite of the strong distance dependency of the energy transfer efficiency. One problem is the incomplete fluorescent labeling of the molecules, which leads to the so-called zero-efficiency peak caused by FRET pairs with missing or nonfluorescing acceptor dyes. Other problems occur due to spectral bleed through, direct acceptor excitation, and the difficulty to obtain the quantum efficiencies of the dyes and the detection efficiencies of the corresponding detectors. In order to correct these defects, the donor as well as the acceptor are excited alternatingly using pulsed interleaved excitation. Time-correlated single-photon counting enables the measurement of fluorescence lifetime; hence, the FRET efficiency can also be derived from the decrease of the donor fluorescence lifetime. The universal time-tagged time-resolved data format allows to retrieve all the necessary information from the fluorescence photons detected during the measurement. [ABSTRACT FROM PUBLISHER]

Complex spectra of Xe and Sn, and their feasibility for use in the lithographic extreme ultraviolet (EUV) source, are investigated. By combining calculations of atomic data using the HULLAC code and the Whiam collisional radiative model with a simple radiative transfer model, the EUV spectrum is shown to originate from a large number of fine structure transitions. Satellite lines of 4d-4f and 4d-5p transitions from near ten times ionized states are found to make a significant contribution to the emission from an optically thick plasma. The wavelengths and transition probabilities of emission lines, charge state distribution, and level population in the plasma, as well as radiation intensity from a laser-produced plasma source have been calculated. The effect of opacity is taken into account assuming a local thermodynamic equilibrium population in the plasma. The calculated result reproduces the observed spectra both for Xe and Sn, showing applicability of the present method to the spectroscopy of hot dense plasmas. [ABSTRACT FROM PUBLISHER]

Abstract: Absorption and emission properties of Pr3+ doped mixed alkali chloroborophosphate glasses have been reported in the UV-VIS-NIR region. A modified Judd–Ofelt (JO) approach has been employed to evaluate the intensity parameters , from the experimentally determined oscillator strengths. These parameters are compared with those obtained from the standard JO theory. The evaluated JO parameters are utilized for the calculation of various radiative parameters such as radiative transition rates (AR), radiative lifetimes (), fluorescence branching ratios () and the integrated absorption cross-section (∑) for stimulated emission from different excited states of Pr3+ ion. From the measured emission spectra, the principal fluorescence transitions of interest are identified and their stimulated emission cross-sections () and branching ratios () were determined. The measured branching ratios are in close agreement to the branching ratios predicted by the modified JO parameters. From these investigations, it is observed that the modified JO theory provides the positive values for the parameters and also significant improvement between the measured and calculated oscillator strengths. [Copyright &y& Elsevier]

We consider the combination of nonequilibrium Auger suppression with cavity enhancement, this being either resonant cavity enhancement (RCE) or photonic crystal enhancement (PCE) as a means to suppress generation-recombination processes in intrinsic semiconductor-based long wavelength infrared detectors. The aim is to approach the background-limited operation of narrow-bandgap compound semiconductor photodetectors in the 3-14 μm infrared wavelength range without cooling or possibly with slight cooling. Auger generation-recombination processes are suppressed utilizing exclusion, extraction, magnetoconcentration, or some of their combinations. The residual radiative recombination is removed by enclosing the detector active area into a cavity with a radiative shield (resonant cavity or photonic crystal) and using the benefits of reabsorption (photon recycling) to effectively increase radiative lifetime. [ABSTRACT FROM PUBLISHER]

In this paper the author places forth a new approach to determine the radiative recombination lifetimes of photo-generated carriers in quantum well solar cells. The calculations are performed for a hypothetical AlxGa1−xAs/GaAs quantum well solar cell. A similar device for which existing data is available is used for comparison. The foundation of the approach is the use of the original equations proposed by Shockley et al. using the assumption that photo-carrier generation is probabilistically controlled, a new approach to photo-carrier generation is derived and determination of the carrier lifetimes is possible. The results obtained for the AlGaAs/GaAs cell fall within accuracy of the existing experimental data. [Copyright &y& Elsevier]

Vibrationally excited N2H+ and N2D+ ions with internal energies of at least 1.3 eV have been produced by electron ionization of a mixture of N2 and H2 (or D2). Their radiative overall lifetime has been determined using the monitor ion technique in a triple cell ICR spectrometer.Theoretical calculation of the vibrational energy levels up to 2.3 eV and of the radiative lifetimes for the fundamental transition of the three normal modes of each isotopomer has been performed in order to help the qualitative analysis of the experimental results.Excitation of ν1 stretching mode is quickly relaxed and is not observed in our experimental conditions. The measured overall lifetimes correspond mainly to excitation of ν2 bending mode. Excitation of the ν3 stretching above v=2 for N2H+ and v=3 for N2D+ seems to be negligible. [Copyright &y& Elsevier]

The TDMs of the transitions are calculated between the X3Σ–, A3Π, a1Δ, b1Σ+, and c1Π states and between the X3Σ– 1 , X3Σ– 0+ , A3Π 2 , A3Π 1 , A3Π 0+ , A3Π 0– , a1Δ 2 , b1Σ+ 0+ , and c1Π 1 states. The radiative lifetimes are 0.42 – 1.45 and 0.44 – 0.72 μs for the A3Π and c1Π states, respectively. The radiative lifetime of the A3Π 2 state is 0.44 – 1.95 μs, which is almost the same as that of the A3Π 0+ and A3Π 0– states. The radiative lifetime of the A3Π 1 state is slightly larger than that of the A3Π 2 , A3Π 0+ , and A3Π 0– states. The radiative lifetimes of the a1Δ 2 and b1Σ+ 0+ states are 2.6 – 432.8 s and 0.26 – 59 ms, respectively. The A3Π 2 – X3Σ– 1 , A3Π 1 – X3Σ– 1 , A3Π 0+ – X3Σ– 1 , A3Π 0– – X3Σ– 1 , b1Σ+ 0+ – X3Σ– 0+ , c1Π 1 – a1Δ 2 , and c1Π 1 – b1Σ+ 0+ transitions are strong. [Display omitted] • Lifetime is 0.44–0.72 μs for the c1Π state. • Lifetimes of the A3Π 2 , A3Π 0+ , and A3Π 0– state were almost the same. • Lifetime is 2.6 – 432.8 s for the a1Δ 2 state and 0.42 – 1.45 μs for the A3Π state. • Lifetime of the b1Σ+ 0+ state is 17 – 59 ms for υ ≤ 8 and 0.26 – 2.8 ms for υ ≥ 9. Properties of the transitions between Ω states originating from the X3Σ–, A3Π, a1Δ, b1Σ+, and c1Π states of NH were investigated herein. The radiative lifetimes of the A3Π state were 0.42, 0.43, 0.44, 0.50, 0.58, 0.70, 0.90, and 1.45 μs for the υ = 0 – 7 levels; and those of the c1Π state were 0.44, 0.54, and 0.72 μs for υ = 0 – 2, respectively. The radiative lifetimes of the A3Π 2 state were 0.48, 0.53, 0.60, 0.68, 0.79, 0.95, 1.21, and 1.95 μs for υ = 0 – 2, respectively, which are slightly larger than those of the A3Π state for same υ. The radiative lifetimes of the A3Π 2 state were almost the same as those of the A3Π 0+ and A3Π 0– states. The radiative lifetimes of the A3Π 2 , A3Π 0+ , and A3Π 0– states were slightly larger than those of the A3Π 1 state. The radiative lifetimes of the first 16 levels of the a1Δ 2 state varied from 2.4 to 432.8 s. Those of the b1Σ+ 0+ state were between 0.3 and 72 ms. Those of the c1Π 1 state were determined as approximately 0.44, 0.54, and 0.72 μs for υ = 0 – 2, respectively. The radiative lifetimes calculated herein compared well with the available experimental results. The Franck–Condon factors and Einstein A coefficients of all possible transitions were calculated. The results reported herein provide useful guidelines for future investigations, both experimental and theoretical. [ABSTRACT FROM AUTHOR]

• b3Π – d3Δ transition is weak. • A1Π – X1Σ+ and E1Σ+ – X1Σ+ transitions are strong. • Lifetime is 4.3 – 9.8 ms for the a3Σ+ 1 state and 3.8 – 35.4 ms for a3Σ+ 0– state. • Lifetime is 117 – 380 μs for the b3Π 0+ state and 73 – 581 μs for the b3Π 1 state. • Lifetime is 107.6 – 120.5 ns for the A1Π state and 12.8 – 14.1 ns for the E1Σ+ state. The transition properties of the X1Σ+, C1Σ–, D1Δ, A1Π, E1Σ+, a3Σ+, d3Δ, and b3Π states of silicon monosulphide were investigated using the complete active space self-consistent field method, which was followed by the internally contracted multireference configuration interaction approach. The transition dipole moments were calculated for the dipole–allowed transitions between these singlet states and for all transitions between the X1Σ+, a3Σ+, d3Δ, and b3Π states. The radiative lifetimes of the first 16 vibrational levels were 107.6 – 120.5 ns for the A1Π state and 12.8 – 14.1 ns for the E1Σ+ state. Among these dipole–allowed transitions, the emissions from the A1Π – X1Σ+ and E1Σ+ – X1Σ+ systems were strong, whereas those from the b3Π – d3Δ system were weak. The radiative lifetimes of the first 16 levels were 4.3 – 9.8, 3.8 – 35.4, 2.2 – 7.9, and 11.9 – 14.5 ms for the a3Σ+ 1 , a3Σ+ 0– , d3Δ 1 , and d3Δ 2 states, respectively. These were 117 – 380, 73 – 581, and 137 – 586 μs for the b3Π 0+ , b3Π 1 , and b3Π 2 states, respectively. Among these forbidden transitions, the b3Π 0+ – X1Σ+ 0+ and b3Π 1 – X1Σ+ 0+ transitions were the strongest. The Franck–Condon factors, Einstein A coefficients, and band origins of all these spontaneous emissions were calculated. The transition properties were compared with the available experimental and theoretical results. The transition properties of the X1Σ+, C1Σ–, D1Δ, A1Π, E1Σ+, a3Σ+, d3Δ, and b3Π states of SiS are calculated; the TDMs of the dipole–allowed transitions between the singlet states are determined; and the TDMs of all transitions between the X1Σ+, a3Σ+, d3Δ, and b3Π states are computed. The radiative lifetimes of the first 16 vibrational levels are 107.6 – 120.5 ns for the A1Π state and 12.8 – 14.1 ns for the E1Σ+ state. These are 4.3 – 9.8, 3.8 – 35.4, 2.2 – 7.9, and 11.9 – 14.5 ms for the a3Σ+ 1 , a3Σ+ 0– , d3Δ 1 , and d3Δ 2 states, respectively. And these are 117 – 380, 73 – 581, and 137 – 586 μs for the b3Π 0+ , b3Π 1 , and b3Π 2 states, respectively. Among all dipole–allowed transitions, the A1Π – X1Σ+ and E1Σ+ – X1Σ+ transitions are strong, whereas the b3Π – d3Δ transition is weak. Among all forbidden transitions, the b3Π 0+ – X1Σ+ 0+ and b3Π 1 – X1Σ+ 0+ transitions are the strongest. [Display omitted] [ABSTRACT FROM AUTHOR]

• Lifetime is approximately 88.7 – 175.6 µs for the e2Σ+ 1/2 state. • d2Π 1/2 – a2Σ– 1/2 and d2Π 3/2 – a2Σ– 1/2 transitions are the strongest. • Lifetimes are 29.3 – 40.4 and 21.2 – 30.1 µs for the d2Π 1/2 and d2Π 3/2 states, respectively. • Lifetimes are 4.8 – 679.5 and 2.2 – 431 ms for the c2Π 1/2 and c2Π 3/2 states, respectively. • d2Π 3/2 – b2Δ 3/2 , 5/2 , c2Π 3/2 , e2Σ+ 1/2 – c2Π 1/2 , 3/2 , and d2Π 1/2 – b2Δ 3/2 , c2Π 1/2 transitions are strong. Detecting aluminum silicon can yield useful information concerning the depletion of silicon and aluminum and their recycling in astrophysical sources. In addition, such detection can be helpful for understanding gas–phase aluminum and silicon chemistry in the interstellar/circumstellar atmosphere. However, only a few transition properties of this radical have been reported. Therefore, the potential energy curves of several lowest–lying doublet states and the transition dipole moments between them were calculated using the icMRCI approach. Core–valence correlation correction, scalar relativistic correction, and spin–orbit coupling effect were included to improve the accuracy of transition properties. The radiative lifetimes of the first 16 levels were approximately 4.8 – 679.5 ms for the c2Π 1/2 state, 2.2 – 431 ms for the c2Π 3/2 state, 29.3 – 40.4 µs for the d2Π 1/2 state, 21.2 – 30.1 µs for the d2Π 3/2 state, and 88.7 – 175.6 µs for the e2Σ+ 1/2 state. The spontaneous emissions from the c2Π 1/2 and c2Π 3/2 states to the a2Σ– 1/2 , b2Δ 3/2 , and b2Δ 5/2 states and those from the e2Σ+ 1/2 state to the d2Π 1/2 and d2Π 3/2 states were located in the radio–frequency region. The d2Π 1/2 – a2Σ– 1/2 and d2Π 3/2 – a2Σ– 1/2 transitions were the strongest, followed by d2Π 1/2 – b2Δ 3/2 , d2Π 3/2 – b2Δ 3/2 , d2Π 3/2 – b2Δ 5/2 , d2Π 1/2 – c2Π 1/2 , d2Π 3/2 – c2Π 3/2 , e2Σ+ 1/2 – c2Π 1/2 , and e2Σ+ 1/2 – c2Π 3/2 transitions. The spontaneous emissions from these systems were located in the infrared region. The variation in the radiative lifetime of a level υ versus the rotational quantum number J was investigated for the d2Π 1/2 , d2Π 3/2 , and e2Σ+ 1/2 states. The radiative lifetimes of the first 16 vibrational levels were roughly 4.8 – 679.5 ms for the c2Π 1/2 state, 2.2 – 431 ms for the c2Π 3/2 state, 29.3 – 40.4 µs for the d2Π 1/2 state, 21.2 – 30.1 µs for the d2Π 3/2 state, and 88.7 – 175.6 µs for the e2Σ+ 1/2 state. The spontaneous emissions from the c2Π 1/2 and c2Π 3/2 states to the a2Σ– 1/2 , b2Δ 3/2 , and b2Δ 5/2 states and those from the e2Σ+ 1/2 state to the d2Π 1/2 and d2Π 3/2 states are distributed in the radio–frequency region. The emissions from the d2Π 1/2 – a2Σ– 1/2 and d2Π 3/2 – a2Σ– 1/2 systems are the strongest, followed by d2Π 1/2 – b2Δ 3/2 , d2Π 3/2 – b2Δ 3/2 , d2Π 3/2 – b2Δ 5/2 , d2Π 1/2 – c2Π 1/2 , d2Π 3/2 – c2Π 3/2 , e2Σ+ 1/2 – c2Π 1/2 , and e2Σ+ 1/2 – c2Π 3/2 transitions. The spontaneous emissions from these systems are located in the IR region. [Display omitted] [ABSTRACT FROM AUTHOR]

• Lifetime is 9 – 20 and 12 – 22 μs for the A2Π 1/2 and A2Π 3/2 states, respectively. • B2Σ+ 1/2 –A2Π 3/2 , B2Σ+ 1/2 –A2Π 1/2 and C2Π 3/2 –A2Π 1/2 transitions are strong. • C2Π 3/2 – X2Σ+ 1/2 , C2Π 1/2 – X2Σ+ 1/2 and C2Π 1/2 –A2Π 3/2 transitions are the strongest. • b4Δ 1/2 –X2Σ+ 1/2 , b4Δ 1/2 –A2Π 3/2 and b4Δ 1/2 –A2Π 1/2 forbidden transitions are the strongest. • Lifetimes are 361 – 553 and 298 – 513 ns for the C2Π 1/2 and C2Π 3/2 states, respectively. A number of experiments have been performed to measure the transition properties of the low–lying states of boron monosulfide; however, only a few theoretical results have been reported in the literature. Thus, the transition properties of several of the lowest–lying states are investigated herein. The potential energy curves of the Ω states generated from the X2Σ+, A2Π, B2Σ+, C2Π, a4Σ+, and b4Δ states and the transition dipole moments between them were calculated using icMRCI approach. The radiative lifetimes of the first 16 levels were of the order of 9 – 20, 12 – 22, and 1.3 – 6.5 μs for the A2Π 1/2 , A2Π 3/2 , and B2Σ+ 1/2 states, respectively; those were approximately 361 – 553 and 298 – 513 ns for the C2Π 1/2 and C2Π 3/2 states, respectively. The C2Π 3/2 – X2Σ+ 1/2 , C2Π 1/2 – X2Σ+ 1/2 , and C2Π 1/2 – A2Π 3/2 transitions were the strongest, followed by the B2Σ+ 1/2 – A2Π 3/2 , B2Σ+ 1/2 – A2Π 1/2 , and C2Π 3/2 – A2Π 1/2 transitions. The transitions from the a4Σ+ and b4Δ states to the X2Σ+ state were evaluated. The radiative lifetimes of the first 16 levels were of the order of 3.2 – 6.0, 8.9 – 17.3, and 61 – 7644 ms for the a4Σ+ 3/2 , a4Σ+ 1/2 , and b4Δ 5/2 , respectively; those were approximately 15 – 1430 and 7 – 1006 μs for the b4Δ 3/2 and b4Δ 1/2 states, respectively. Among these forbidden transitions, the emissions from the b4Δ 1/2 – X2Σ+ 1/2 , b4Δ 1/2 – A2Π 3/2 , b4Δ 1/2 – A2Π 1/2 , b4Δ 1/2 – X2Σ+ 1/2 , b4Δ 1/2 – A2Π 3/2 , and b4Δ 1/2 – A2Π 1/2 systems were strong. The distribution of the radiative lifetime at a level υ versus the rotational quantum number J was evaluated for the A2Π 1/2 , A2Π 3/2 , B2Σ+ 1/2 , C2Π 1/2 , and C2Π 3/2 states. The radiative lifetimes are 9 – 20, 12 – 22, and 1.3 – 6.5 μs for the A2Π 1/2 , A2Π 3/2 , and B2Σ+ 1/2 states, respectively; those were 361 – 553 and 298 – 513 ns for the C2Π 1/2 and C2Π 3/2 states, respectively; these are of the order 3.2 – 6.0, 8.9 – 17.3, and 61 – 7644 ms for the a4Σ+ 3/2 , a4Σ+ 1/2 , and b4Δ 5/2 , respectively; those were 15 – 1430 and 7 – 1006 μs for the b4Δ 3/2 and b4Δ 1/2 states, respectively. The C2Π 3/2 – X2Σ+ 1/2 , C2Π 1/2 – X2Σ+ 1/2 , and C2Π 1/2 – A2Π 3/2 transitions are strongest, followed by the B2Σ+ 1/2 – A2Π 3/2 , B2Σ+ 1/2 – A2Π 1/2 , and C2Π 3/2 – A2Π 1/2 transitions. The b4Δ 1/2 – X2Σ+ 1/2 transition is the strongest, followed by the b4Δ 1/2 – A2Π 3/2 and b4Δ 1/2 – A2Π 1/2 forbidden transitions. The strong emissions from the A2Π 3/2 – X2Σ+ 1/2 and A2Π 1/2 – X2Σ+ 1/2 systems are mainly in the visible region; only a small number are in the IR and UV regions. The strong emissions from the B2Σ+ 1/2 – X2Σ+ 1/2 , C2Π 1/2 – A2Π 3/2 , C2Π 1/2 – A2Π 1/2 , C2Π 3/2 – A2Π 3/2 , and C2Π 3/2 – A2Π 1/2 systems are located in the UV and visible region; those from the B2Σ+ 1/2 – A2Π 3/2 and B2Σ+ 1/2 – A2Π 1/2 transitions are in the visible region; those from the C2Π 3/2 – X2Σ+ 1/2 and C2Π 1/2 – X2Σ+ 1/2 systems are in the UV region; those from C2Π 3/2 – B2Σ+ 1/2 and C2Π 1/2 – B2Σ+ 1/2 systems are of IR light. [Display omitted] [ABSTRACT FROM AUTHOR]

• Lifetimes are 93 – 254 and 23.9 – 30.3 µs for the c4Δ and d4Σ– states, respectively. • Lifetimes are 410 – 1044 and 380 – 906 µs for the B2П 1/2 and B2П 3/2 states, respectively. • Lifetimes are 0.27 – 66 and 1.5 – 2.38 × 104 ms for the A2Σ+ and b4Σ+ states, respectively. • Emissions from the C2Σ+ 1/2 to the X2П 3/2 , X2П 1/2 , and A2Σ+ 1/2 states were the strongest. • Lifetimes are 0.95 – 1.31 µs for the C2Σ+ 1/2 state. The potential energy curves of X 2Π, A 2Σ+, B 2Π, C 2Σ+, a 4Π, b 4Σ+, c 4Δ, and d 4Σ– states of SiP molecules and the transition dipole moments of the transitions between these states were calculated using the CASSCF method, followed by the icMRCI approach. The radiative lifetimes of the first 16 vibrational levels were 0.27 – 66 and 1.5 – 2.38 × 104 ms for the A 2Σ+ and b 4Σ+ states, respectively. Those were 146 – 497, 93 – 254, 23.9 – 30.3, and 0.85 – 1.1 µs for the B 2Π, c 4Δ, d 4Σ–, and C 2Σ+ states, rspectively. The spin–orbit coupling constants of the X 2Π, B 2Π, a 4Π, and b 4Σ+ states were evaluated. Including the spin–orbit coupling effect, the radiative lifetimes of the A 2Σ+ 1/2 , B 2П 1/2 , B 2П 3/2 , C 2Σ+ 1/2 , a 4П –1/2 , a 4П 1/2 , a 4П 3/2 , a 4П 5/2 , b 4Σ+ 1/2 , and b 4Σ+ 3/2 states were calculated. The lifetimes of the first 16 levels were 0.35 – 0.42, 3.1 – 5.5, 1.3 – 5.8, and 30 – 57 s for the a 4П –1/2 , a 4П 1/2 , a 4П 3/2 , and a 4П 5/2 states, respectively. And those were 2.3 – 268 and 2.6 – 257 ms for the b 4Σ+ 1/2 and b 4Σ+ 3/2 states, respectively. The SOC effect made the radiative lifetimes of the A 2Σ+, B 2Π, and C 2Σ+ states become longer. Among the spontaneous emissions between these Ω states, those from the C 2Σ+ 1/2 state to the X 2П 3/2 , X 2П 1/2 , and A 2Σ+ 1/2 states were the strongest. The results indicated that the strong emissions originated from the lower levels of the C 2Σ+ 1/2 state. Furthermore, almost all of these strong emissions were in the visible region. All emissions generating from the a 4П –1/2 , a 4П 1/2 , a 4П 3/2 , and a 4П 5/2 states are extremely weak. The radiative–lifetime distribution of each level υ versus the rotational quantum number J was evaluated for several Ω states. [Display omitted] [ABSTRACT FROM AUTHOR]

• B2Σ+ 1/2 – X2Σ+ 1/2 transition is strong. • A2Π 1/2, 3/2 – X2Σ+ 1/2 and B2Σ+ 1/2 – A2Π 1/2, 3/2 transitions are strong. • Lifetimes are 10 μs for the A2Π 1/2, 3/2 states and 100 ns for the B2Σ+ 1/2 state. • Lifetimes are 10 and 10 – 100 ms for the a4Σ+ 1/2 and a4Σ+ 3/2 , respectively. • Lifetimes are 10, 0.1 – 1, and 10 ms for the b4Δ 1/2 , b4Δ 3/2 , and b4Δ 5/2 states, respectively. The potential energy curves of X 2Σ+, A 2Π, B 2Σ+, a 4Σ+, and b 4Δ states and their Ω states of CP were calculated using the icMRCI approach. The transition dipole moments between these states were computed. To improve the accuracy of the potential energy curves, core–valence correlation and scalar relativistic corrections were considered. The radiative lifetimes were approximately 10 μs for the A 2Π 3/2 and A 2Π 1/2 states and 100 ns for the B2Σ+ 1/2 state; those were approximately 10, 10 – 100, 10, 0.1 – 1, and 10 ms for the a 4Σ+ 1/2 , a 4Σ+ 3/2 , b 4Δ 1/2 , b 4Δ 3/2 , and b 4Δ 5/2 states, respectively. The spontaneous emissions from the B 2Σ+ 1/2 – X 2Σ+ 1/2 system were strong, followed by the A 2Π 3/2 – X 2Σ+ 1/2 , A 2Π 1/2 – X 2Σ+ 1/2 , B 2Σ+ 1/2 – A 2Π 3/2 , and B 2Σ+ 1/2 – A 2Π 1/2 transitions. The strong emissions from the A 2Π 3/2 – X 2Σ+ 1/2 and A 2Π 1/2 – X 2Σ+ 1/2 systems were in the infrared region; those from the B 2Σ+ 1/2 – X 2Σ+ 1/2 system were in the visible and ultraviolet regions; and those from the B 2Σ+ 1/2 – A 2Π 3/2 , and B 2Σ+ 1/2 – A 2Π 1/2 systems were of visible light. A simple comparison shows that the effect of the spin–orbit coupling on the radiative lifetimes of the A 2Π and B 2Σ+ states was significant. The radiative–lifetime distribution of each level υ versus the rotational quantum number J was evaluated for υ ≤ 15 and J ≤ 70.5. The PECs of the X2Σ+, A2Π, B2Σ+, a4Σ+, and b4Δ states and their Ω states of CP are calculated. The TDMs between these states are computed. The radiative lifetimes are of the order of 10 μs for the A2Π 3/2 and A2Π 1/2 states and 100 ns for the B2Σ+ 1/2 state. Those are of the order of 10, 10 – 100, 10, 0.1 – 1, and 10 ms for the a4Σ+ 1/2 , a4Σ+ 3/2 , b4Δ 1/2 , b4Δ 3/2 , and b4Δ 5/2 states, respectively. The SOC effect evidently increases the radiative lifetime of the A2Π state; however, it significantly decreases the radiative lifetime of the B2Σ+ state. The B2Σ+ 1/2 – X2Σ+ 1/2 transition is strong, followed by the A2Π 3/2 – X2Σ+ 1/2 , A2Π 1/2 – X2Σ+ 1/2 , B2Σ+ 1/2 – A2Π 3/2 , and B2Σ+ 1/2 – A2Π 1/2 transitions. The strong emissions from the A2Π 3/2 – X2Σ+ 1/2 and A2Π 1/2 – X2Σ+ 1/2 systems are in the IR region; those from the B2Σ+ 1/2 – X2Σ+ 1/2 system are in the visible and UV regions, and those from the B2Σ+ 1/2 – A2Π 3/2 , and B2Σ+ 1/2 – A2Π 1/2 systems are in the visible region. [Display omitted] [ABSTRACT FROM AUTHOR]

• A1Π – X1Σ+ transition is strong. • Almost all strong emissions are located in the UV region. • Radiative lifetime of all levels of the A 1Π state are 6.2–16.7 ns. • Radiative lifetime of a level υ gradually increases with J for all levels. • Most of the emissions are in the UV region. Only a few are in the visible region. The potential energy curves of the X1Σ+ and A1Π states of aluminum monochloride radical and the transition dipole moments between them were calculated using the icMRCI approach. Core–valence correlation and scalar relativistic corrections were applied. The extrapolation of the potential energies to the complete basis set limit was considered to improve the quality of the potential energy curves. In order to accurately calculate the rovibrational transition positions of the A1Π – X1Σ+ system, the experimental T e value of the A1Π state was used to improve the reliability of the ab initio results. The radiative lifetimes of all vibrational states of the A1Π state were calculated and compared with the available experimental and theoretical results. The variation of the radiative–lifetime distribution with the rotational quantum number was obtained. The rovibrational transition positions, Einstein A coefficients, oscillator strengths, and Franck–Condon factors of the P, Q, and R branches of the vibronic emissions of this system were calculated up to J = 150. The Einstein A coefficients were large for numerous vibronic bands, indicating that these transitions were easily measured via spectroscopy. A Comparison with available measurements shows that the transition properties reported herein are accurate. [ABSTRACT FROM AUTHOR]

• Reliable and accurate potential energy curves for Λ + S and Ω states of SrI. • Most complete characterization of the states to date. • Dipole and transition moments, Einstein A v´v´´ emission coefficients, and radiative lifetimes. • Experimental investigation of the new A´ 2Δ state should be significantly facilitated. A high-level theoretical approach – SA-CASSCF/MRCI – is used to explore the electronic structure and spectroscopic properties of a manifold of low-lying electronic states of the radical strontium monoiodide, SrI. For both Λ + S and Ω representations, potential energy curves are constructed, and the associated spectroscopic parameters derived. Dipole moment functions and vibrationally averaged dipole moments allow one to quantify the polarity of the various states. With the transition dipole moment functions, Einstein A v'v" coefficients for spontaneous emission were computed for pairs of selected states and radiative lifetimes evaluated for the low-lying vibrational levels of the excited electronic states. Reliable results are also provided for the yet unknown states A' 2Δ and E 2Σ+ which can guide spectroscopists to their experimental detection. Combined with recent theoretical work on SrF, SrCl, and SrBr one now can have a broad perspective of the trends in spectroscopic properties of this series of halides. [Display omitted] [ABSTRACT FROM AUTHOR]

Earlier, it was shown by the EPR method that at a very low concentration of the Nd3+ ion in the Nd3+:CaF 2 crystal, highly symmetric cubic centers with the O h symmetry are formed. In the present study, the optical centers of the Nd3+ ion with an anomalously long radiative lifetime τ R = 13.6 ms of the 4F 3/2 (1) crystal-field (CF) level in the Nd3+ (0.05 at.%): Na+ (0.2 at.%): CaF 2 single crystal at T = 7 K were detected by the method of time-resolved site-selective fluorescence laser spectroscopy. Its fluorescence excitation at the 4I 9/2 (1) → 4G 5/2 (1) transition of Nd3+ is in a longer wavelength spectral range compared to optical tetragonal (C 4v) L-, orthorhombic (C s) pair M-, and quartet N- centers. New optical centers exhibit inhomogeneous splitting and can be attributed to nearly cubic sites with symmetry close to O h. Also numerous Nd3+ optical sites in the Nd3+ (0.03 at.%): CaF 2 and Nd3+ (0.05 at.%): Na+ (0.2 at.%): CaF 2 crystals at T = 7 K with τ R = 240 μs ‒ 8.5 ms of the 4F 3/2 (1) CF level of Nd3+ were detected in a shorter wavelength spectral range compared to the nearly cubic sites. Among them, the sites with the longest τ R = 8.5 ms except for the nearly cubic sites, which were identified as C 2v symmetry sites. Their radiative lifetime is about six times that of the C 4v site (τ R = 1.4 ms). This means that, for optical sites without a center of inversion, the radiative lifetime of the excited state at sites with higher symmetry can be almost an order of magnitude less than at sites with lower symmetry. We explained this result by the different distance between the Nd3+ ion and the ion, which compensates for the excess of its charge. Thus, we have demonstrated the use of the Judd-Ofelt approach to explain the difference in the rates of emission of the excited state in different optical sites of the same rare-earth ion in the same crystal matrix. • We detected fluorescence of Nd3+ nearly cubic sites in the Nd3+:Na+:CaF 2 crystal. • The 4F 3/2 (1) CF level lifetime of Nd3+ of the nearly cubic sites is long, τ R = 13.6 ms. • An inhomogeneous splitting of the spectral lines of the nearly cubic sites is found. • τ R of the C 2v symmetry site is about six times that of the C 4v higher symmetry site. • We explained the result by different Nd3+-Na+ distances using the Judd-Ofelt approach. [ABSTRACT FROM AUTHOR]

• C1Π – X1Σ+, C1Π – A1Σ– and c3Π – a3Σ+ transitions are strong. • Lifetimes are 10 – 100 ns for the C1Π state and 10 μs for the c3Π state. • A1Σ– 1 – a3Σ+ 0– , B1Δ 2 – b3Δ 3 , b3Δ 2 – a3Σ+ 1 and d3Σ– 0+ – a3Σ+ 0– transitions are strong. • Lifetimes are 0.1 – 10, 10 and 0.1 – 1 ms for the B1Δ 2 , a3Σ+ 1 and b3Δ 2 states, respectively. • Lifetimes are 10–100, 10–100, and 100 μs for the A1Σ– 0– , d3Σ– 0+ and d3Σ– 1 states, respectively. The potential energy curves of the X1Σ+, A1Σ–, B1Δ, C1Π, a3Σ+, b3Δ, c3Π, and d3Σ– states of PO+ and the transition dipole moments between these states were calculated using the CASSCF method, and then the icMRCI approach. To accurately compute the transition properties, core–valence correlation and scalar relativistic corrections were taken into account. The spin–orbit coupling calculations were used to determine the transition properties of the A1Σ–, B1Δ, a3Σ+, and b3Δ states, from which no spontaneous emissions were generated owing to the limitations from the dipole–allowed transition selection rule. The radiative lifetime was approximately 10 – 100 ns for the C1Π state and 10 μs for the c3Π state. Among these dipole–allowed transitions, the emissions from the C1Π – X1Σ+ system was the strongest and was followed by the C1Π – A1Σ– and c3Π – a3Σ+ transitions. The radiative lifetime was approximately 10 – 100, 10 – 100, and 100 μs for the A1Σ– 0– , d3Σ– 0+ , and d3Σ– 1 states, respectively. Those were of the order of 0.1 – 10, 10, 10 – 100, 1 – 100, and 0.1 – 1 ms for the B1Δ 2 , a3Σ+ 1 , a3Σ+ 0– , b3Δ 1 , and b3Δ 2 states, respectively. Among the spontaneous emissions generated from these Ω states, those from the A1Σ– 1 – a3Σ+ 0– , A1Σ– 1 – a3Σ+ 1 , B1Δ 2 – b3Δ 3 , b3Δ 2 – a3Σ+ 1 , d3Σ– 0+ – a3Σ+ 0– , and d3Σ– 1 – a3Σ+ 1 transitions were relatively strong. The transition properties reported herein are expected to provide useful guidelines for the detection in future experiments. The radiative lifetimes are approximately 10 – 100 ns for the C1Π state and 10 μs for the c3Π state. Among all the dipole–allowed transitions involved in this study, the C1Π – X1Σ+ transition is the strongest and then followed by the C1Π – A1Σ– and c3Π – a3Σ+ transitions. The radiative lifetimes are approximately 10 – 100 μs for the A1Σ– 0– and d3Σ– 0+ states and 100 μs for the d3Σ– 1 state. The lifetimes are approximately 0.1 – 10, 10, 10 – 100, 1 – 100, and 0.1 – 1 ms for the B1Δ 2 , a3Σ+ 1 , a3Σ+ 0– , b3Δ 1 , and b3Δ 2 states, respectively. Among all these spontaneous emissions generated from A1Σ–, B1Δ, b3Δ, and d3Σ– states, those from the A1Σ– 1 – a3Σ+ 0– , A1Σ– 1 – a3Σ+ 1 , B1Δ 2 – b3Δ 3 , b3Δ 2 – a3Σ+ 1 , d3Σ– 0+ – a3Σ+ 0– , and d3Σ– 1 – a3Σ+ 1 transitions are strong. The dipole–allowed d3Σ–– c3Π transition is weaker than the spin–forbidden d3Σ– 0+ – a3Σ+ 0– transition; the dipole–allowed d3Σ– – c3Π transition is weaker than the spin–forbidden d3Σ– 1 – a3Σ+ 1 transition. [Display omitted] [ABSTRACT FROM AUTHOR]

• Spin-forbidden a − X , a ′ − X and spin-allowed A − X transition moments of CO were obtained using fully relativistic approach. • The radiative lifetimes of a 3 Π and A 1 Π states were evaluated as functions of vibrational and rotational quantum numbers. • The lifetimes derived for the a 3 Π state are in a near perfect agreement with their best experimental counterparts. • The intercombination transition probabilities were found to be almost strictly proportional to the squared fine structure constant α. The spin-forbidden a 3 Π − X 1 Σ + , a ′ 3 Σ + − X 1 Σ + and spin-allowed A 1 Π − X 1 Σ + electronic transitions dipole moments of carbon monoxide have been ab initio studied in the framework of multi-reference Fock space coupled cluster method combined with the finite-field approach and the generalized relativistic pseudo-potential model for the effective introducing the relativity in all-electron correlation treatment. Radiative lifetimes, τ i (v ′ , J ′) , of the upper i ∈ [ a 3 Π , A 1 Π ] states were evaluated as a function of vibrational, v ′ , and rotational, J ′ , quantum numbers. The τ a -values derived for the triplet a 3 Π 1 (0 , 1) and a 3 Π 2 (0 , 2) states at the highest level of computation were found to be 2.59 and 142 ms, which are near perfect agreement with their best experimental counterparts (J. J. Gilijamse, et al., J. Chem. Phys., 127 , 221102 (2007)). The intercombination a − X , a ′ − X transition probabilities were numerically proved to be proportional to α 2 , where α = e 2 / ℏ c is the fine structure constant. [ABSTRACT FROM AUTHOR]

• Lifetime is 100 ns for the B2Σ+ state. • Lifetimes are 10 ms for the a4Σ+ 3/2 and a4Σ+ 1/2 states and 10 µs for the A2Π 3/2 and A2Π 1/2 states. • Lifetimes are 1–10, 1, 10–100, and 1–10 µs for the A2Π, 22Π, 12Σ–, and C2Δ states, respectively. • A2Π – X2Σ+, B2Σ+ – X2Σ+, B2Σ+ – A2Π, 22Π – A2Π, and C2Δ – A2Π transitions are strong. • 22Π – B2Σ+, 12Σ– – 22Π, and C2Δ – 22Π transitions are weak. The transition dipole moments of the dipole–allowed transitions between the X2Σ+, A2Π, B2Σ+, 22Π, 12Σ–, and C2Δ states of the carbon monosulfide cation were calculated using the complete active space self–consistent field method, followed by the internally contracted multireference configuration interaction approach. The transition dipole moments of the spin–forbidden transitions from the a4Σ+ state to the X2Σ+ and A2Π states were computed. The radiative lifetimes were of the order of 1 – 10 µs, 100 ns, 1 µs, 10 – 100 µs, and 1 – 10 µs for the A2Π, B2Σ+, 22Π, 12Σ–, and C2Δ states, respectively. The transition frequencies, Einstein A coefficients, and Franck–Condon factors of all these spontaneous vibronic emissions from these systems were calculated. The emissions from the A2Π – X2Σ+, B2Σ+ – X2Σ+, B2Σ+ – A2Π, 22Π – A2Π, and C2Δ – A2Π systems were strong, suggesting that the 22Π state could be measured in a spectroscopy experiment via 22Π – A2Π transition. Those from the 22Π – B2Σ+, 12Σ– – 22Π, and C2Δ – 22Π systems were weak. The radiative lifetimes of the a4Σ+ 1/2 and a4Σ+ 3/2 states were approximately 10 ms. Among these spin–forbidden transitions, the emissions from the a4Σ+ 3/2 – A2Π 3/2 system were relatively strong. The radiative–lifetime distribution of each vibrational level versus the rotational quantum number was evaluated for the A2Π, B2Σ+, 22Π, 12Σ–, C2Δ, and a4Σ+ states. Image, graphical abstract The radiative lifetimes were approximately 1 – 10 µs, 100 ns, 1 µs, 10 – 100 µs, and 1 – 10 µs for the A2Π, B2Σ+, 22Π, 12Σ–, and C2Δ states, respectively. They were of the order of 10 ms for the a4Σ+ 3/2 and a4Σ+ 1/2 states and 10 µs for the A2Π 3/2 and A2Π 1/2 states. The A2Π – X2Σ+, B2Σ+ – X2Σ+, B2Σ+ – A2Π, 22Π – A2Π, and C2Δ – A2Π transitions were strong, and the 22Π – B2Σ+, 12Σ– – 22Π, and C2Δ – 22Π transitions were weak. The 22Π state could be measured spectroscopically via the 22Π – A2Π transition. Among the spin–forbidden transitions, the a4Σ+ 3/2 – A2Π 3/2 transition was relatively strong. The radiative lifetime of each level increased gradually with J for the A2Π, 22Π, 12Σ–, C2Δ, a4Σ+ 3/2 , and a4Σ+ 1/2 states. [ABSTRACT FROM AUTHOR]

• Lifetimes are 1–10, 0.1–1, and 1 μs for the A4Π, D4Σ–, and E4Π states, respectively. • Lifetimes are 10–100 and 1 – 10 μs for the d2Σ+ and e2Π states, respectively. • Lifetimes are 0.1–103 and 0.1–102 ms for the b2Δ and c2Σ– states, respectively. • Lifetimes are 1–104 and 1–103 ms for the B4Δ and C4Σ+ states, respectively. • A4Π – X4Σ–, D4Σ– – X4Σ–, E4Π – X4Σ–, and E4Π – A4Π transitions are strong. In this study, the potential energy curves were calculated for the X4Σ–, A4Π, B4Δ, C4Σ+, D4Σ–, E4Π, a2Π, b2Δ, c2Σ–, d2Σ+, and e2Π states of silicon boride. The transition dipole moments were computed for all dipole–allowed transitions between these states. The complete active space self-consistent field method was used for calculations, followed by the valence internally contracted multireference configuration interaction approach. The radiative lifetimes were approximately 1 – 10 μs, 0.1 – 1 μs, 1 – 10,000 ms, 1 – 1000 ms, and 1 μs for the A4Π, D4Σ–, B4Δ, C4Σ+, and E4Π states, respectively. Of these transitions between the six lowest–lying quartets, the spontaneous emissions from the A4Π – X4Σ–, D4Σ– – X4Σ–, E4Π – X4Σ–, and E4Π – A4Π systems were strong, whereas those from the B4Δ – A4Π, C4Σ+ – A4Π, and E4Π – B4Δ transitions were weak. The radiative lifetimes were approximately 0.1 – 1000 ms, 0.1 – 100 ms, 10 – 100 μs, and 1 – 10 μs for the b2Δ, c2Σ–, d2Σ+, and e2Π states, respectively. Of the transitions between the a2Π, b2Δ, c2Σ–, d2Σ+, and e2Π states, the spontaneous emissions from the e2Π – b2Δ and e2Π – c2Σ– systems were relatively strong, whereas those from the b2Δ – a2Π transition were relatively weak. The transition frequencies, Einstein A coefficients, and Franck–Condon factors of all spontaneous vibronic bands from these transitions were calculated. The results obtained in this study were compared with experimental and other theoretical values. The radiative–lifetime distribution varying with rotational angular quantum number J was calculated when J ≤ 50.5 for a particular vibrational level of these states. The radiative lifetimes are approximately 1 – 10, 0.1 – 1, 1, 10 – 100, and 1 – 10 μs for the A4Π, D4Σ–, E4Π, d2Σ+, and e2Π states, respectively; and those are of the order of 0.1 – 1000, 0.1 – 100, 1 – 10,000, 1 – 1000 ms for the b2Δ, c2Σ–, B4Δ, and C4Σ+ states, respectively. Of the transitions between the quartet states, the A4Π – X4Σ–, D4Σ– – X4Σ–, E4Π – X4Σ–, and E4Π – A4Π transitions are strong, whereas the B4Δ – A4Π, C4Σ+ – A4Π, and E4Π – B4Δ transitions are weak. Of the transitions between the doublet states, the e2Π – b2Δ and e2Π – c2Σ– transitions are relatively strong, whereas the b2Δ – a2Π transition is relatively weak. The radiative lifetime of a particular υ changes quickly as J increases for lower vibrational levels of the B4Δ, C4Σ+, b2Δ, c2Σ–, and d2Σ+ states; whereas the radiative lifetime of a particular υ increases or decreases as J increases for the other states. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The quasirelativistic approach was used to derive transition data for the Rh-like W 29 + tungsten ion. The quasirelativistic approach was developed specifically for the calculation of spectral parameters of highly charged ions. The relativistic effects were taken into account in the Breit–Pauli approximation. The configuration interaction method was applied to include electron correlation effects. The ground W 29 + configuration 4p 6 4d 9 and two odd-parity configurations 4p 5 4d 10 and 4p 6 4d 8 4f were investigated. Different sets of configuration-interaction extensions were applied for assessment of calculation accuracy. The level energies, radiative lifetimes τ , and Landé g -factors were determined for levels of the excited configurations 4p 5 4d 10 and 4p 6 4d 8 4f and the ground configuration 4p 6 4d 9. The radiative transition wavelengths λ and emission transition probabilities A for the electric and magnetic transitions of high multipole order among the levels of these configurations were produced. The uncertainties of computed spectroscopic parameters were evaluated. Such a complete and inclusive data set for the levels of two excited configurations and their radiative properties in W 29 + is reported for the first time. [ABSTRACT FROM AUTHOR]

Lifetime calculations of Th II J = 1.5 and 2.5 odd states are performed with configuration–interaction many-body perturbation theory (CI-MBPT). For many J = 2.5 states, lifetimes are quite accurate, but two pairs of J = 2.5 odd states and many groups of J = 1.5 states are strongly mixed, making theoretical predictions unreliable. To solve this problem, a method based on intensities is used. To relate experimental intensities to lifetimes, two parameters, one an overall coefficient of proportionality for transition rates and one temperature of the Boltzmann distribution of populations, are introduced and fitted to minimize the deviation between theoretical and intensity-derived lifetimes. For strongly mixed groups of states, the averaged lifetimes obtained from averaged transition rates were used instead of individual lifetimes in the fit. Close agreement is obtained. Then intensity branching ratios are used to extract individual lifetimes for the strongly mixed states. The resulting lifetimes are compared to available directly measured lifetimes and reasonable agreement is found, considering limited accuracy of intensity measurements. The method of intensity-based lifetime calculations with fit to theoretical lifetimes is quite general and can be applied to many complex atoms where strong mixing between multiple states exists. [ABSTRACT FROM AUTHOR]