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Photoionization (PI) of the Ti9+ ion is investigated using the Dirac R-matrix method. Multi-configuration Dirac–Fock (MCDF) calculations are performed to construct accurate target functions. Good agreement of energy levels and radiative transition rates indicate the accuracy of target functions. PI cross sections show good consistency between length and velocity forms. The results are consistent with the previous theoretical values in high-energy regions. Partial waves' contribution to the total PI cross sections are discussed for the GS and MS. Moreover, the PI cross sections are dominated by many resonance structures and affected by the channel coupling effects in the low-energy region. In addition to providing data for the Opacity Project TOPbase, the present work promotes plasma simulation and diagnosis. [ABSTRACT FROM AUTHOR]

The n+-InAs/n0-InAs1 –ySby/p-InAsSbP heterostructures with asymmetric band offsets at the heteroboundaries of the active region have been grown by vapor-phase epitaxy from organometallic compounds on InAs substrates. The forward branch of the current–voltage characteristics of the obtained heterostructures at low temperatures has segments with the tunneling conduction. The energy-band diagram of the double InAs/InAs1 –ySby/InAsSbP heterostructure is calculated in the range of compositions (y < 0.2) of the narrow-gap active region. The InAs1 –ySby/InAsSbP heterojunction is shown to be a II type heterojunction in this composition range. The electroluminescence observed in the experiment for the n+-InAs/n0-InAs1 ‒ySby/p-InAsSbP heterostructures with the active region in compositions y > 0.14 is due to interface radiative transitions with participation of localized hole states at the II type heteroboundary. [ABSTRACT FROM AUTHOR]

The work discusses mechanisms of formation, crystal structure, some features of defect formation, and composition of the solid carbide film formed from a hydrocarbon and hydrides on the Si surface at low (< 900 °C) growth temperatures. It is shown that a system of macrodefects and a subsurface structure similar to porous silicon are formed under a carbide layer as a result of long-term growth of thick carbide layers. The presence of a solid solution transition layer between the carbide layer and the silicon substrate is manifested in the structure of luminescence spectra of studied structures in the near IR region. The most probable mechanisms of observed radiative transitions were established by analysing the temperature behavior of spectral lines and calculating the layer distribution of structures of light-excited non-equilibrium charge carriers. [ABSTRACT FROM AUTHOR]

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 Euþ3 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. [ABSTRACT FROM AUTHOR]

We report electroluminescence originating from L-valley transitions in n-type Ge/Si0.15Ge0.85 quantum cascade structures centered at 3.4 and 4.9 THz with a line broadening of Δ f / f ≈ 0.2. Three strain-compensated heterostructures, grown on a Si substrate by ultrahigh vacuum chemical vapor deposition, have been investigated. The design is based on a single quantum well active region employing a vertical optical transition, and the observed spectral features are well described by non-equilibrium Green's function calculations. The presence of two peaks highlights a suboptimal injection in the upper state of the radiative transition. Comparison of the electroluminescence spectra with a similar GaAs/AlGaAs structure yields one order of magnitude lower emission efficiency. [ABSTRACT FROM AUTHOR]

A study of the electroluminescence of asymmetric InAs/InAs1 – ySby/InAsSbP light-emitting diode heterostructures with a molar fraction of InSb in the ternary solid solution in the active region y = 0.15 and y = 0.16 in the temperature range 4.2–300 K is reported. It is found on the basis of experimental data that a staggered type-II heterojunction is formed at the InAs1 – ySby/InAs0.41Sb0.28P0.40 heterointerface. It is shown that interfacial radiative transitions at the type-II heterointerface make a dominant contribution in the temperature range of 4.2–180 K. This enables minimization of the temperature dependence of the operating wavelength of a light-emitting diode. [ABSTRACT FROM AUTHOR]

We present a new method aimed at improving the efficiency of component by component ionization modelling of intervening quasar absorption-line systems. We carry out cloud-by-cloud, multiphase modelling making use of cloudy and Bayesian methods to extract physical properties from an ensemble of absorption profiles. Here, as a demonstration of method, we focus on four weak, low-ionization absorbers at low redshift, because they are multiphase but relatively simple to constrain. We place errors on the inferred metallicities and ionization parameters for individual clouds, and show that the values differ from component to component across the absorption profile. Our method requires user input on the number of phases and relies on an optimized transition for each phase, one observed with high resolution and signal-to-noise ratio. The measured Doppler parameter of the optimized transition provides a constraint on the Doppler parameter of H  i , thus providing leverage in metallicity measurements even when hydrogen lines are saturated. We present several tests of our methodology, demonstrating that we can recover the input parameters from simulated profiles. We also consider how our model results are affected by which radiative transitions are covered by observations (for example, how many H  i transitions) and by uncertainties in the b parameters of optimized transitions. We discuss the successes and limitations of the method, and consider its potential for large statistical studies. This improved methodology will help to establish direct connections between the diverse properties derived from characterizing the absorbers and the multiple physical processes at play in the circumgalactic medium. [ABSTRACT FROM AUTHOR]

In the framework of a quasi-molecular approach, the formation of hydrogen atom in the pre-recombination period of evolution of the Universe is analysed quantitatively. Calculations in an adiabatic multilevel representation enable estimates of probabilities of radiative transitions. The quasi-molecular mechanism of recombination allows the formation of hydrogen molecular ion, |${\mathrm{ H}_2}^+$|⁠ , in its ground state. The probability of this process is comparable with the probability of the creation of atomic hydrogen. The participation of a second proton in the recombination increases the binding energy of an electron and decreases the rate of recombination of hydrogen. [ABSTRACT FROM AUTHOR]

Using known values of rotational and centrifugal distortion constants in conjunction with electric dipole moment of NH2CHO, we have calculated energies of rotational levels in the ground vibrational state, and the probabilities for radiative transitions between the levels. The radiative transition probabilities in conjunction with the scaled values of collisional rate coefficients are used in the Sobolev LVG analysis of NH2CHO. There are some strong lines. For ortho-NH2CHO, we have found one transition 110-111 showing anomalous absorption and five transitions 615-514, 717-616, 716-615, 818-717, 817-716 showing emission feature. For para-NH2CHO, six emission transitions 505-404, 606-505, 707-606, 808-707, 909-808, 100.10-909 are found. Out of these 12 transitions, three transitions, 110-111, 505-404, and 808-707, are already found in the ISM. Other relatively weaker lines are also found in the ISM. In addition to the observed lines, 9 transitions may play important role in the identification of NH2CHO in a cosmic object. [ABSTRACT FROM AUTHOR]

Cyanamide (NH2CN) has pyramidal equilibrium structure with two substates, denoted by 0+ and 0–. For each state of NH2CN, knowing rotational and centrifugal distortion constants in conjunction with electric dipole moment, energies for rotational levels and the probabilities for radiative transitions between the levels are calculated. The radiative transition probabilities in conjunction with scaled values for rate coefficients for collisional transitions between the levels are used in the Large Velocity Gradient analysis for each substate. For each substate, we have found anomalous absorption in three doublets at high temperature and weak MASER action at low temperature. We have also found emission feature in nine transitions in each substate. These transitions, along with the observed ones, may play important role for identification of NH2CN in a cosmic object. [ABSTRACT FROM AUTHOR]

Developing dual-state fluorescence materials with high emission efficiency both in solution and solid states is still a challenge. Herein, a functionalized pyrazoline derivative (NF) was designed and synthesized. NF exhibited high blue emission efficiency in both THF solution and solid states with the absolute fluorescence quantum yields of 58% and 43%, respectively. The mechanism of this unique fluorescence behavior was systematically studied with the help of single-crystal structure analysis. The results showed that a close-knit molecular structure existed due to intramolecular C–H⋯π interactions, which can impair the intramolecular rotation to accelerate the radiative transition in the mono-molecule state (in dilute solution). Moreover, the steric hindrance and intermolecular hydrogen-bond interactions of the substituent groups can restrict the close packing and prompt the formation of J-aggregates in the aggregation state, which resulted in high emission performance in the solid state. Meanwhile, the dual-state blue emission property of NF was utilized for the picric acid (PA) detection in the solution state and on a test paper by the synergistic effects of photo-induced electron transfer (PET) and Förster resonance energy transfer (FRET) processes. The limit of detection as low as 6.80 × 10−7 M achieved in the THF–H2O mixture. This work provided a new scope for the design of high dual-state blue emission materials. [ABSTRACT FROM AUTHOR]

Crystals of new borate KTm[B4O6(OH)4] ⋅ 3H2O (sp. gr. Р 1m, a = 4.5472(7) Å, c = 12.151(3) Å) have been obtained under hydrothermal conditions at T = 280°C and P = 100 atm. Their structure contains packets of two polar mica-like tetrahedral layers [B4O6(OH)4]∞∞, connected by TmO6 octahedra. The interpacket space is occupied statistically by K atoms and water molecules. A similar layer is typical of peprossiite and its synthetic analogue NdAl2.07[B4O10]O0.6 and KTa[B4O6(OH)4](OH)2 ⋅ 1.33H2O, which have another sp. gr. P 2m and trigonal-prismatic coordination of heavy atoms. The structure of the new compound is compared with two other structures of this family: KGd[B6O10(OH)2] and KHo[B6O10(OH)2]. A previously unknown combination of simple mica-like layers and octahedra in one packet is implemented in the new member of the family. All compounds under consideration are characterized by disorder and statistical occupancy of sites, especially in the interpacket space. The KTm[B4O6(OH)4] ⋅ 3H2O crystals demonstrate strong emission of blue light due to the radiative 4f–4f transitions of the Tm3+ cation. The most intense transition in the photoluminescence spectrum is 1D2–3F4 at 450 nm. [ABSTRACT FROM AUTHOR]

• Ln:Lu 2 O 3 (Ln = Pr, Eu, Tb, Dy) were prepared by SPS using co-precipitated powders. • Only powders with high-quality crystallinity yielded partially transparent ceramics. • Luminescence of dense ceramics is determined by radiative transitions of dopant ions. • Additional annealing of sintered ceramics increases its integral light yield. • SPS made dense ceramics of Pr, Tb and Dy-doped Lu 2 O 3 is reported for the first time. Dense ceramics of Ln:Lu 2 O 3 (Ln = Pr, Eu, Tb, Dy) were obtained using spark plasma sintering (SPS) from co-precipitated nanocrystalline powders. X-ray diffraction, scanning and transmission electron microscopies were used for the characterization of Ln:Lu 2 O 3 powders obtained by various annealing regimes. Transparency of the sintered ceramics was achieved when powders with highly developed crystallinity were used for sintering. Sintered ceramics exhibited luminescence with a characteristic emission based on the element doped into the Lu 2 O 3 host. The light yield of the sintered ceramics improved when the sintered ceramics was further annealed. The annealing of the sintered ceramics also improved the transmittance in the visible region; however, the transparency was lost when the annealing temperature was too high. To our best knowledge, the SPS fabrication of dense ceramics of Pr3+, Tb3+ and Dy3+-doped Lu 2 O 3 is reported here for the first time. [ABSTRACT FROM AUTHOR]

A unified framework for describing dense plasma screenings from warm dense matter to hot dense matter, including gradient correction and exchange-correlation, has been recently proposed by Stanton and Murillo [Phys. Rev. E 91,033104 (2015)]. With this unified description of linear screening, the energy levels, absorption oscillator strengths, and radiative transition probabilities of hydrogen-like plasmas are reported for a wide range of critical screening parameters (plasma temperatures and densities), where the bound level nl merges into continuum. The importance of both finite temperature gradient correction and exchange correlation increases with the increasing plasma coupling strength or the Coulomb coupling parameter Γ, and the effect of exchange correlation is generally greater than that of finite temperature gradient correction. Further results from the weakly coupled and strongly coupled limits or Debye plasmas and dense quantum plasmas also show consistency with those from the unified framework, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Er3+ doped bismuth flourophosphate glasses were successfully prepared by high temperature melting method. • The influence of modifier cations as ligand field surrounding Er3+ ions on the optical properties was analyzed. • The visible and near-infrared emission of Er3+ doped bismuth flourophopsphate glasses were investigated. • Broadband emissions at visible and near-infrared were observed with the excitation of 379 nm and 980 nm respectively. • Various luminescence properties determined and compared with different compositional incorporation. Bismuth flourophosphate glasses doped with Er3+ ions (0.5 mol %) were synthesized using different modifier fluorides with the aid of melt quenching route. The glass samples were labelled as PBiBa AF T (where AF = Li, Na, Mg, K, Ca and Sr fluorides). The influence of cations of network modifiers on the structure and thereby spectroscopic properties of Er3+ ions was analysed via Powder XRD, FTIR, optical absorption and photoluminescence. Existence of relevant vibrational groups and modifications in structure due to the different admixture modifier cations were recognized via FTIR spectra. The Judd-Ofelt parameters abide by the trend Ω 2 > Ω 6 > Ω 4 in the PBiBa Li T, PBiBa K T, PBiBa Ca Tand PBiBa Sr T glasses whereas the trend was noticed to be Ω 2 > Ω 4 > Ω 6 for PBBi Na T and PBiBa Mg T glasses respectively. The visible emission spectra were recorded by exciting at 379 nm exhibit three emission bands centered at 526 nm, 544 nm and 686 nm. NIR emission spectra were recorded by exciting at 980 nm exhibit broad emission at 1535 nm. Admixture of different cations could exhibit change in luminescence intensity and radiative parameters of the prepared glasses. Spectroscopic parameters such as radiative transition probability (A), branching ratio (β), absorption cross section (∑), effective bandwidth (Δλ eff) and optical band gain (σ e × Δλ eff) are calculated. The mid infrared spectroscopic features were investigated. [ABSTRACT FROM AUTHOR]

Peroxynitrite (ONOO−), as a strong oxidative biomolecule, is considered a potential biomarker of drug-induced liver injury (DILI) that could disturb biochemistry processes and cause a great variety of liver diseases. However, it remains a significant challenge to discover quickly and track accurately ONOO− in vivo environments even if these active substances have aggravated liver damage. Herein, we developed a peroxynitrite-activable mitochondria-targeted phosphorescent chemodosimeter (Ru-Mit) for DILI monitoring, which was designed by covalently linking ruthenium(II) complex with the strong electron-withdrawing malononitrile moiety. In the presence of ONOO−, the chemodosimeter hard to be oxidized exhibited excellent turn-on phosphorescent response at 610 nm with a longer lifetime (∼ 300 ns). The sensing mechanism indicated the malononitrile group in Ru-Mit was removed via the hydrolysis of C=C bond, accompanied by the change of electronic structure and the enhancement of radiative transitions. Further, reliable signals are capable of not only imaging exogenous and endogenous ONOO− in mitochondria, but also visualizing APAP-induced and tolcapone-induced ONOO− generation in HepG2 cells by confocal luminescence imaging. This work might provide a new molecular platform to design and develop ONOO− probes, and it might be used as a practical tool to detect ONOO− for the pathogenesis research of DILI. [Display omitted] • A mitochondria-targeted phosphorescent chemodosimeter (Ru-Mit) is synthesized for detection of ONOO−. • Ru-Mit displays excellent turn-on phosphorescent response towards ONOO− at 610 nm with large Stokes shift (150 nm). • Ru-Mit exhibits fast response to ONOO− (within 60 s) and long phosphorescence lifetime (342 ns). • The phosphorescent chemodosimeter is applied for monitoring ONOO− during drug-induced liver injury in HepG2 cells. [ABSTRACT FROM AUTHOR]

Eight bound singlet and triplet electronic states of the diatomic dication ScH2+ are characterized theoretically at the SA-CASSCF/icMRCI/aug-cc-pV5Z level of theory by the construction of potential energy curves, and the evaluation of spectroscopic parameters. The states dissociating into the first channel are all thermodynamically stable. For the ground state, covalent bonding plays a relevant role in the stabilization of the molecule; for the other states, bonding results mainly from electrostatic charge-induced dipole interaction. Dipole moment (relative to the center of mass) functions and vibrationally averaged dipole moments quantify the polarity of the molecule. After evaluating transition moment functions, transition probabilities for spontaneous emission for selected pair of states are estimated by the Einstein A v´,v´´ coefficients and the stronger transitions identified; radiative lifetimes are also reported. Not yet known experimentally, this work is expected to motivate experimental investigations of transition metal-monohydrides diatomic dications. [Display omitted] [ABSTRACT FROM AUTHOR]

• Reliable potential energy curves for the bound quartet electronic states of VAr2+ and VKr2+. • Most complete characterization of these dications states to date. • Compared with the monocations, the dications are more strongly bound. • Dipole and transition moments, Einstein A v′v′′ emission coefficients, and radiative lifetimes. Six low-lying bound quartet electronic states of the diatomic dications VAr2+ and VKr2+ are characterized theoretically at the SA-CASSCF/icMRCI/aug-cc-pV5Z level of theory by the construction of potential energy curves, and the evaluation of spectroscopic parameters. These molecules were found to be thermodynamically stable, where binding arises from purely electrostatic charge-induced dipole interaction; they are more strongly bound than the corresponding monocations. Their polarity is described by dipole moment functions and vibrationally averaged dipole moments. Transition probabilities for spontaneous emission for selected pair of states are estimated by the Einstein A v′v′′ coefficients and the stronger transitions identified; radiative lifetimes are also reported. Not yet known experimentally, this work is expected to motivate further experimental investigations of transition metal-rare-gas diatomic dications. [Display omitted] [ABSTRACT FROM AUTHOR]

This article presents a description of the structural-optical relationship in amorphous borate glass, with a decent investigation of Judd-Ofelt parameters to understand the effect of structural changes on optical properties due to the erbium oxide addition. Using density measurements, the effect of heavy molecular weight and larger ionic radius of erbium oxide was demonstrated. FT-IR analysis revealed the BO 3 to BO 4 conversion, confirming the network polymerization and connectivity. Astonishingly, the effect of erbium oxide on the increased band gap energy and the mitigated Urbach energy was demonstrated. Interestingly, Judd-Ofelt analysis was utilized to demonstrate the impact of the composition changes on the relation between the structural changes and optical properties. The influence of excited configurations of E r 3 + ions was measured from the line strengths. The hypersensitive transitions from I 15 / 2 4 t o H 11 / 2 4 and G 9 / 2 4 were observed at 375 nm and 519 nm, which have relatively higher intensities compared to other ones. Thus, they are attractive transitions for light emitting devices, LEDs, and solid lasers. The decreased values of Ω 2 parameter is related to the increase in symmetry and high polarization around E r 3 + ions. Consequently, the decrement in Ω 2 suggests that the bond nature between E r 3 + and O 2 − ions tends to be more ionic. Calculations of radiative parameters such as spontaneous radiative transition probability, radiative lifetime, and branching ratio were presented. The hypersensitive transitions have the highest values of the spontaneous radiative transition probability, predicting their high luminescence efficiency in glass host, besides the effectiveness of their usability in designing photonic devices. The obtained high branching ratio confirmed the lasing action of E r 3 + ions in the glass host, especially the hypersensitive transitions of E r 3 + ions. • Alkali borate glasses doped erbium oxide were prepared. • The structure-property relationship was described by different techniques. • Judd-Ofelt intensity parameters confirmed the ionic nature of E r 3 + with ligands. • Wide band gap and related parameters confirm the usability of samples in optics realm. • Hypersensitive transitions have the highest values of radiative parameters. [ABSTRACT FROM AUTHOR]

Lu 2(1- x) Pr 2 x O 3 nanoscintillators (x = 0.0005, 0.001, 0.0015, 0.003, 0.005) with excellent red emission and a response time of 185.7 μs were synthesized by a coprecipitation method. It is found that both photoluminescence and radioluminescence intensities show an initial rising and then decreasing trend with increasing Pr3+ concentration and the strongest intensity can be obtained at x = 0.001. By determining the average distance between Pr and O, the radiative transition processes from 3P 0 and 1D 2 to 3H 4 and nonradiative transition process from 3P 0 to 1D 2 can be confirmed. Meanwhile, the afterglow level of Lu 2 O 3 :Pr3+ nanoscintillators with an average size of 112.3 nm was found to be 2190 ppm. Based on the spectral data and density functional theory calculations, the afterglow can be related to Pr L u · traps due to the presence of Pr4+ in Lu 2 O 3 :Pr. When Sm3+ ions were doped into Lu 2 O 3 :Pr3+, it is found that it leads to the decreased creation of Pr4+, the reduced afterglow level and the improved radioluminescence. By means of Lu 2 O 3 :Pr3+, Sm3+ nanoparticles being dispersed into polymethyl methacrylate (PMMA) polymer, PMMA-Lu 2 O 3 :Pr3+, Sm3+ composite films with fast response time and radiation resistance were prepared by a rotating coating method. The static X-ray imaging with a spatial resolution of 5.5 lp/mm using the composite film as an imaging screen was realized at extremely low safe dose of 4.6 μ G y. Meanwhile, for the broken electric wire used as an object, the clear X-ray image can be observed. Our results suggest that Lu 2 O 3 :Pr3+, Sm3+ nanoscintillators have potential applications in medical imaging and nondestructive testing. • Sm3+ and Pr3+ codoped Lu 2 O 3 nanoscintillators were synthesized by coprecipitation method. • Sm3+ doping improves the radioluminescence intensity of Pr singly doped sample by 1.8 times. • Sm3+ doping reduces the afterglow level of the Lu 2 O 3 :Pr samples by decreasing the presence of Pr4+. • Lu 2 O 3 :Pr3+,Sm3+ nanoscintillators can be potentially used as imaging screens in X-ray imaging. [ABSTRACT FROM AUTHOR]

Luminescence thermometry has been extensively exploited in the last decades both from the fundamental and applied point of views. The application of photoluminescent nanoparticles on the microscopic level based on rare-earth doped (RED) nanostructures is yet a challenge. Distinct underlying physical mechanisms in the RED nanomaterials have been exploited, such as intensity ratio between radiative transitions associated with thermally coupled energy levels, energy peak and lifetime of an excited state variations with the temperature. The drawbacks of such systems are the relatively low thermal sensitivity (S r), and the large temperature uncertainty. To overcome that, several research groups have been seeking new functionalized materials. The majority of the efforts have been directed towards increasing S r with record around 10%°C−1, which is, however, considered unsatisfactory. We propose the use of an automated machine learning tool to retrieve an ideal pipeline improving the response of photoluminescence thermometers. As a proof-of-concept, we used Nd3+-doped YAG nanoparticles, excited at 760 nm, and the photoluminescence spectra in the range from 860 nm to 960 nm as input parameters. In addition to the improvement in the accuracy (> 5.5 × over traditional methods), the implementation is very simple, without the requirement of any deconvolution procedure or knowledge of any underlying physical mechanism. Our findings demonstrate that this approach is resilient to natural variances across various spectral acquisitions, which may otherwise lead to an inaccurate estimation of temperature, opening the door for real-time applications. Our open-source code is designed to be accessible to individuals without programming experience. [Display omitted] • Automated machine learning selects the best model. • Best model improves the accuracy of photoluminescent thermometers (5.5x). • Photoluminescence of neodymium ions was used as a proof-of-concept. • The proposal can be extended to any photoluminescent material. • An open-source code is available to individuals without programming experience. [ABSTRACT FROM AUTHOR]

Nd3+ ion doped lithium aluminum gadolinium borophosphate glasses were synthesized by melt quenching technique. The hypersensitive transitions were identified in the absorption spectra for ultraviolet (UV), visible (Vis) and near infrared (NIR) region, which the highest intensity is recorded at the transitions 4I 9/2 →4D 5/2 , 4I 9/2 →4G 5/2 and 4I 9/2 →4F 5/2 with wavelengths of 352, 582 and 804 nm, respectively. The spectroscopic properties of emission spectra in Nd3+ doped present glasses were investigated under 808 nm laser excitation and shows the strongest intensity at 1063 nm, which corresponding the transition 4F 3/2 →4I 11/2. Furthermore, JO parameters (Ω 2 , Ω 4 and Ω 6) are produced, which are then utilized to examine the radiative characteristics of Nd3+ doped glasses for example radiative transition probability (A R), radiative lifetimes (τ rad), branching ratios (β), gain bandwidth (Δλ eff ×σ e), optical gain (σ e ×τ rad) and emission cross-section (σ e). The results demonstrated that the LBPNd0.5 glass might be used in laser applications around 1.058 µm region, which represent highest stimulated emission cross-section (53.49 ×10–21 cm2), higher branching ratio (>0.5), highest quantum efficiency (84.58%), lower non-radiative decay rates (720 s−1) compared with other glasses. • Glasses doped with Nd3 + ion prepared and investigated. • NIR emission at 1058 nm shows the strongest intensity. • Judd-Ofelt parameters showed Ω 6 > Ω 2 > Ω 4 trend. • Radiative properties displayed highest values in transition 4F 3/2 →4I 11/2. • Highest quantum efficiency of LBPNd0.5 glass was found to be 84.58% for 0.5 of Nd 2 O 3. [ABSTRACT FROM AUTHOR]

The ab initio quasirelativistic approach developed specifically for the calculation of spectral parameters of highly charged ions has been used to determine transition data for the Mo-like tungsten ion W 32 +. The configuration interaction method is utilized to include electron correlation effects. The relativistic effects are taken into account in the Breit–Pauli approximation. Level energies, radiative lifetimes τ , Landé g -factors are determined for the ground configuration 4p 6 4d 6 and two excited configurations 4p 5 4d 7 and 4p 6 4d 5 4f. The radiative transition wavelengths λ , emission transition probabilities A , weighted oscillator strengths g f , and transition line strengths S for the electric dipole, electric quadrupole, electric octupole, magnetic dipole, and magnetic quadrupole transitions among the fine-structure levels of these configurations are produced. The uncertainties of computed spectroscopic parameters are evaluated. [ABSTRACT FROM AUTHOR]

Iridium (III) complexes have attracted much attention as electrochemiluminescence (ECL) luminophores, but their inferior ECL efficiency (Φ ECL) in the aqueous solutions has impeded further applications. Herein, meso-tetra (4-carboxyphenyl) porphine (TCPP) was developed as interfacial charge mediator to dramatically enhance aggregation-induced electrochemiluminescence (AIECL) of tris (2-phenylpyridine) iridium(Ⅲ) (Ir(ppy) 3), thus improving its Φ ECL. As an interfacial charge mediator, TCPP can efficiently accelerate the electrooxidation of Ir(ppy) 3 through higher hole transport kinetics. Meanwhile, it is found that its rigid structure can suppress the motions of Ir(ppy) 3 to elevate radiative transition efficiency in emission process. Thus, a significantly enhanced AIECL was achieved for aggregation-induced emission luminogens (AIEgens) Ir(ppy) 3 @TCPP. Compared to monomer Ir(ppy) 3 , Ir(ppy) 3 @TCPP increased ECL efficiency by 18 times. Ir(ppy) 3 @TCPP served as AIEgens to construct ECL biosensor for detecting miRNA-126. Strand-displacement amplification (SDA) coupled with rolling-circle amplification (RCA) for improving the conversion efficiency of target miRNA-126. The integration of excellent AIECL characteristics of Ir(ppy) 3 @TCPP and outstanding amplification efficiency of SDA-RCA endowed sensing system with high sensitivity. The limit of detection (LOD) was as low as 17 aM. This work creatively exploited interfacial charge modulation as an effective way to enhance AIECL efficiency. The prepared Ir(ppy) 3 @TCPP provided much attractive ECL system for bioanalysis. • Interfacial charge modulation was explored to improve AIECL efficiency. • TCPP could accelerate electrooxidation of Ir(ppy) 3 and suppress Ir(ppy) 3 motions. • SDA was coupled with RCA for improving conversion efficiency of target miRNA-126. • AIECL characteristics combined with dual nucleic acid amplification endowed bioassay with high sensitivity. [ABSTRACT FROM AUTHOR]

For the first of its kind, Silver activated (1–9 mol%) Zirconium Titanate nanoparticles (NPs) have been synthesized by green solution combustion method using AloeV era gel extract as a reducing agent followed by calcination at 720 °C for 3 h. All the synthesized samples crystallizes in orthorhombic crystal structure with the space group of P b c n. Initially a less intense peak corresponding to monoclinic ZrO 2 phase is observed up to 7 mol % and thereafter it diminishes at 9 mol %. The surface and bulk morphology were analyzed. The crystallite size increases whereas the direct energy band gap was found to decrease with increase in dopant concentration. Further, the effect of dopant concentration on photoluminescence and electrochemical properties were studied. The PL spectra show a single broad emission peak at 440 nm along with a satellite peak at 466 nm. These peaks appearing in the case of Ag-doped ZTO corresponds to the radiative transition of the excited electrons from occupied d bands to higher states of the Fermi level. The CIE and CCT coordinates imply that the present nanophosphor can be employed as a blue emitting phosphor material in display technology. The cyclic voltammetry analysis is performed for oxidation and redox peaks. EIS revealed the ion transport kinetics and Super capacitance values were obtained from GCD analysis. Specific capacitance values were found to be in the range 279 to 329 F/g for ZTO:Ag (1 to 9 mol%) NPs respectively. Thus, the present synthesized material might find applications in the field of display technology as well as in energy storage materials. [Display omitted] • Nanocrystalline ZrTiO 4 :Ag (1–9 mol%) was synthesized by Green Solution Combustion method using Aloevera gel. • The synthesized sample were characterized by different techniques. • The synthesized nanophosphor is one of the promising candidate for display applications as a blue nanophosphor. • Further, CV analysis and Supercapacitor properties are discussed for high energy deices applications. [ABSTRACT FROM AUTHOR]

Dazzling green emission exhibiting Tb3+ ions doped lanthanum tungstate (LWO) nanophosphors were synthesized by a facile hydrothermally assisted solid-state reaction method. The nanophosphors were determined to have an orthorhombic structure using XRD analysis. In the optimized Tb3+: LWO nanophosphor, FE-SEM revealed aggregated non-uniform nanorods. TEM, FTIR, and XPS studies were performed to examine the material properties. A predominant excitation band was recorded at 488 nm (7F 6 →5D 4) for the Tb3+ doped LWO nanophosphors, along with a moderately intense excitation band at 378 nm (7F 6 →5G 6). Ravishing green emission at 544 nm (5D 4 →7F 5) was obtained from Tb3+ ions containing LWO nanophosphors under excitation at 378 nm and 488 nm. We improved the green emission intensity by increasing the Tb3+ ion concentration up to 14 mol%, which was reduced after 14 mol% due to concentration quenching. The energy-level diagram shows the green radiative transition pathway. The CIE coordinates and color purity were computed for Tb3+: LWO nanophosphors from their emission profiles, and the evaluated coordinates were centralized in the strong green region. A high color purity of 90.1% was obtained appreciably from the optimized Tb3+: LWO nanophosphor. The lifetime of the green emission transition was systematically evaluated based on decay dynamics. The visualization of fingerprints was examined using the optimized green phosphor with an in-depth analysis of the Group-III level details. The non-cytotoxicity of Tb3+ (14 mol%): LWO nanophosphor was confirmed in normal WI-38 lung fibroblast cells. Moreover, these phosphors exhibited strong cytotoxicity against human breast cancer cells of MCF-7. From these results, the synthesized Tb3+ (14 mol%): LWO non-cytotoxic nanophosphor material is considered the best green luminescent material for latent fingerprints in forensic investigation, photonic and anticancer applications. [Display omitted] • An orthorhombic Tb3+: La 10 W 22 O 81 nanophosphor rods were synthesized. • Luminescence of Tb3+ ions was improved by increasing the concentration of Tb3+ions. • Lifetime, CIE coordinates, color purity and cytotoxicity were extensively studied. • Anticancer studies were performed systematically. • Latent finger print application was performed with optimized sample. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two coumarin-based compounds with blue and green emission were prepared. • These compounds have the potential to be used as novel dual-state emitting luminogens. • Positive solvatochromism is found in these molecules. • These molecules exhibit Aggregation-Caused Red Shifted Emission. • Rewritable data storage has been demonstrated using the DSEgen molecule. The development of dual-state organic luminogens with high emission efficiency both in solution and solid phase is still a difficult task. Dual-state emissive fluorescent materials have proven to have a much broader application in several fields. Molecular design plays a significant role in fabricating switchable as well as tunable emissions. Nonetheless, the mechanism of dual-state emission needs to be studied further. Herein, two compounds, Blue-Yellow emissive material (BYEM) and Green-Red emissive material (GREM), have been designed and synthesized for a novel class of luminogens with dual-state emission (DSEgens) properties. These compounds emit luminously in solution state as well as solid state, with Aggregation Caused Red-Shifted Emission (ACRE) emission. Close-packed molecular structure and the steric hindrance effect can reduce the intramolecular rotation solution state, which accelerates the radiative transition of the compound in the solution state. On the contrary, in the solid state, the twisted structure and intermolecular C–H⋯π interactions can indorse the J -aggregation, which leads to the high fluorescence at the solid state. Significant red shift emission at solid state has been supported by theoretical calculations. On the other hand, by combining a partly shared donor–acceptor unit based on the twisted molecule, these compounds have shown good solvatochromic behavior. Gradual redshift emission has been observed as the solvent polarity is increased. These dual state highly emissive compounds can be applied in several industrial applications as well as the biomedical field. [ABSTRACT FROM AUTHOR]

It is crucial for thermally activated delayed fluorescence (TADF) emitters to have both high photoluminescence quantum yield (PLQY) and high reverse intersystem crossing rate (k RISC). A novel TADF emitter, namely 3,6-bis(3,6-bis(diphenylamino)-9 H -carbazol-9-yl)-10-phenylacridin-9(10 H)-one (3,6-DPCz-AD), was designed by introducing N 3 , N 3 , N 6 , N 6 -tetraphenyl-9 H -carbazole-3,6-diamine (DPCz) at 3,6-sites of the acceptor acridin-9(10 H)-one (AD) by nucleophilic substitution. On the acridin-9(10 H)-one ring, the sp2-hybridization of the 10-site N atom leads to high rigidity, which inhibited conformation relaxation of excited state to reduce non-radiative decay. The introduction of large conjugated diphenylamine groups at the 3,6-sites of carbazole not only facilitated the RISC by increasing intramolecular charge transfer and generating a low S 1 -T 1 energy gap (Δ E ST), but also enhanced the radiative transition by enlarging the highest occupied molecular orbital (HOMO) delocalization. As a result, even without the traditional highly distorted structure, 3,6-DPCz-AD exhibited strong TADF characteristics with high k RISC of 5.8 × 105 s−1, high k r of 3.4 × 107 s−1 and a high PLQY of 99% simultaneously. The green organic light-emitting diode (OLED) of 3,6-DPCz-AD showed both a maximum external quantum efficiency (EQE max) of 30.1% and a power efficiency of 83.3 lm W−1. An EQE of 20.1% was still remained at a high brightness of 1000 cd m−2. This is one of the best performances for acridin-9(10 H)-one based TADF emitters ever reported so far. A novel thermally activated delayed fluorescence emitter 3,6-DPCz-AD based on acridone acceptor and 3,6-bis(diphenylamino)-carbazole donors realizes effective trade-off between reverse intersystem crossing and radiative transition through appropriate design strategy, which results in high k RISC > 5 × 105 s−1, k r > 107 s−1 and PLQY of 99% simultaneously and finally leads to high external quantum efficiency over 30% with good efficiency stability in simple-structured green OLED. [Display omitted] • A novel thermally activated delayed fluorescence (TADF) emitter 3,6-DPCz-AD was developed for OLED application. • Incorporating diphenylamine on carbazole donors enhanced TADF feature despite small donor-acceptor angles. • Combination of DPCz as donors and acridone as acceptor facilitated both RISC and radiative transition processes. • High k RISC of 5.8 × 105 s−1, k r of 3.4 × 107 s−1 and PLQY of 99.2% were realized simultaneously. • 3,6-DPCz-AD exhibited a very high EQE max of 30.1% in green OLED with slow efficiency roll-off. [ABSTRACT FROM AUTHOR]

2D V-MoS 2 microsheets have excellent photoelectric application performances due to their unique growth arrangement. Here, we have grown 2D V-MoS 2 microsheets by magnetron sputtering and investigated their optical properties by temperature-dependent (T -dependent) photoluminescence (PL) from 7 to 300 K. At 7 K and 300 K, the direct A and B exciton peaks and the indirect (I) exciton peak can be observed with PL broadening from 2D V-MoS 2 microsheets. With the increase of temperature, the A and B exciton peaks have a red-shift, and the full width at half maximum (FWHM) becomes wider, whereas the intensities of the A and B exciton peaks exhibits different behaviors. The intensity of the A exciton peak reduces while the B exciton peak intensity is rising. Moreover, the I exciton peak obtains an obvious split, which is almost independent of temperature. The above phenomena are closely related to the temperature dependence of band structure, exciton transition and radiative recombination processes in 2D V-MoS 2 microsheets. Our results enrich the understanding of exciton dynamics in 2D V-MoS 2 microsheets and provide valuable information for the development of MoS 2 -based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract—At present, plasmon effects in metal nanoparticles are used, among other purposes, for improvement in the efficiency of light-emitting diodes (LEDs). One new direction can be the application of plasmon properties of nanoparticles for improvement in the characteristics of wireless optical networks, in which data are transferred with the use of LEDs (Li–Fi networks). The study is concerned with issues related to the use of metal nanoparticles with dielectric shells to accelerate the modulation rate of LEDs and, as a consequence, to increase the data transfer rate in wireless optical networks due to an increase in the transition rates in a nanocrystal located near the nanoparticle surface. The dependences of the radiative and nonradiative transition rates in a nanocrystal on the emission wavelength are studied for different diameters of the metal core and different shell thicknesses. It is shown that, by specifying the optimal configuration of a nanoparticle with a shell, it is possible to create conditions such that the increase in the radiative transition rate at the emission wavelength of a nanocrystal will substantially exceed the increase in the nonradiative transition rate. This will allow acceleration of the modulation of LEDs without a loss in their energy efficiency as light sources. The results obtained here can be useful in studying the fluorescence of molecules and nanocrystals near nanoparticles and in improving the characteristics of Li–Fi optical data transfer networks. [ABSTRACT FROM AUTHOR]

Equation of transfer of infrared radiation propagating over a flat surface in a dense molecular gas with small temperature gradients is constructed. Interaction of the radiation field with a gas is manifested in radiative transitions between vibrational, rotational, or vibrational-rotational states of molecules. Therefore, the absorption spectrum of a molecular gas includes hundreds of transitions, and the absorption coefficient as a function of the photon frequency has an oscillatory structure with maxima in the centers of corresponding spectral lines and minima between the centers of neighboring lines. Analysis of the radiative transfer equation for specific problems requires knowledge a large number of parameters for the corresponding radiative transitions in molecules that are contained in the HITRAN data bank. Therefore this equation can be considered as addition to data of the HITRAN bank. The peculiarities of application of the infrared radiation transfer equation to certain cases are analyzed. [ABSTRACT FROM AUTHOR]

The problem of Rydberg atomic spectra in crossed electric F and magnetic B fields (combined Stark–Zeeman effects), as well as an oscillating electric field are under consideration. The main problem is the great array of radiative transitions between the Rydberg atomic states. The different versions of semiclassical approaches are applied for the solution of the problem. New approximate selection rules are established to simplify the matrix elements of radiative transitions, making it possible to reduce the complex expressions of Gordon's hypergeometric series to the trivial trigonometric functions. Simple analytical formulas for the dipole matrix elements of a Rydberg hydrogen-like atom in external crossed electric and magnetic fields for Hnα are obtained. The specific calculations are presented for n = 10 to 9 transition both for parallel and perpendicular orientations of F–B fields. The result of Blokhintsev for a single Stark component in oscillating field is generalized for the array of radiative transitions between Rydberg atomic states. Such spectra with large values of modulation index are compared with static ones. [ABSTRACT FROM AUTHOR]

Red luminescence is found in off‐white tris(iodoperchlorophenyl)methane (3I‐PTMH) crystals which is characterized by a high photoluminescence quantum yield (PLQY 91 %) and color purity (CIE coordinates 0.66, 0.34). The emission originates from the doublet excited state of the neutral radical 3I‐PTMR, which is spontaneously formed and becomes embedded in the 3I‐PTMH matrix. The radical defect can also be deliberately introduced into 3I‐PTMH crystals which maintain a high PLQY with up to 4 % radical concentration. The immobilized iodinated radical demonstrates excellent photostability (estimated half‐life >1 year under continuous irradiation) and intriguing luminescent lifetime (69 ns). TD‐DFT calculations demonstrate that electron‐donating iodine atoms accelerate the radiative transition while the rigid halogen‐bonded matrix suppresses the nonradiative decay. [ABSTRACT FROM AUTHOR]

Red luminescence is found in off‐white tris(iodoperchlorophenyl)methane (3I‐PTMH) crystals which is characterized by a high photoluminescence quantum yield (PLQY 91 %) and color purity (CIE coordinates 0.66, 0.34). The emission originates from the doublet excited state of the neutral radical 3I‐PTMR, which is spontaneously formed and becomes embedded in the 3I‐PTMH matrix. The radical defect can also be deliberately introduced into 3I‐PTMH crystals which maintain a high PLQY with up to 4 % radical concentration. The immobilized iodinated radical demonstrates excellent photostability (estimated half‐life >1 year under continuous irradiation) and intriguing luminescent lifetime (69 ns). TD‐DFT calculations demonstrate that electron‐donating iodine atoms accelerate the radiative transition while the rigid halogen‐bonded matrix suppresses the nonradiative decay. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) nanothermometers are sought after in biomedicine when it comes to measuring temperatures subcutaneously. Yet, temperature sensing within the third biological imaging window (BW‐III), where the highest contrast images can be obtained, remains relatively unexplored. Here, LiErF4/LiYF4 rare‐earth nanoparticles (RENPs) are studied as NIR nanothermometers in the BW‐III. Under 793 nm excitation, LiErF4/LiYF4 RENPs emit around 1540 nm, corresponding to the 4I13/2 → 4I15/2 radiative transition of Er3+. The fine Stark structure of this transition allows to delineate intensity regions within the emission band that can be used for single‐band ratiometric nanothermometry. These nanothermometers have a relative temperature sensitivity of ≈0.40% °C−1. The temperature‐dependent energy transfer to the surrounding solvent molecules plays a significant role in the thermometric properties of the RENPs. In addition, Ce3+ ions are doped in the core of the RENPs to examine whether it affects the NIR emission and temperature sensitivity. Ce3+ at 1 mol% marginally influences the downshifting emission intensity of the RENPs, yet increases the relative thermal sensitivity to ≈0.45% °C−1. Furthermore, Ce3+ quenches the visible upconversion emission of the RENPs. Together, LiErF4:Ce3+/LiYF4 RENPs enable single‐band photoluminescence nanothermometry in the BW‐III, with the future possibility of its integration within multifunctional decoupled theranostic nanostructures. [ABSTRACT FROM AUTHOR]

Solid solutions Gd2(1 –x)TbxEuxO3 (where x = 1 and 2.5 mol %) are prepared by the sol–gel method with subsequent annealing at 700–1200°C in air and hydrogen atmospheres. It is found by XRD and IR spectroscopy that the solutions undergo the chemical and phase transformations from the cubic modification to the monoclinic one in the annealing process and change the degree of crystallinity. Microinclusions of the Tb7O12:Eu3+ phase are present in a solid solution under certain annealing conditions, which are not formed in a hydrogen atmosphere or with a high activator concentration of 2.5 mol % at 1200°C. In accordance with these transformations, the Tb3+ and Eu3+ photoluminescence activators are redistributed over the C3i centrosymmetric and C2 noncentrosymmetric crystal lattice sites and the Cs surface states. These rearrangements give rise to changes in the parameters of the photoluminescence spectra, which are associated with a change in the ways of transferring the excitation energy of the main radiative transitions of the Tb3+ and Eu3+ photoluminescence activators. [ABSTRACT FROM AUTHOR]

Context. The star-formation rates and stellar densities found in young massive clusters suggest that these stellar systems originate from gas at densities of n(H2) > 106 cm−3. Until today, however, the physical characterization of this ultra high density material remains largely unconstrained in observations. Aims. We investigate the density properties of the star-forming gas in the OMC-1 region located in the vicinity of the Orion Nebula Cluster (ONC). Methods. We mapped the molecular emission at 652 GHz in OMC-1 as part of the APEX-SEPIA660 Early Science. Results. We detect bright and extended N2H+ (J = 7–6) line emission along the entire OMC-1 region. Comparisons with previous ALMA data of the (J = 1–0) transition and radiative transfer models indicate that the line intensities observed in this N2H+ (7–6) line are produced by large mass reservoirs of gas at densities n(H2) > 107 cm−3. Conclusions. The first detection of this N2H+ (7–6) line at parsec-scales demonstrates the extreme density conditions of the star-forming gas in young massive clusters such as the ONC. Our results highlight the unique combination of sensitivity and mapping capabilities of the new SEPIA660 receiver for the study of the ISM properties at high frequencies. [ABSTRACT FROM AUTHOR]

The change in the state of sky from cloudy to cloudless (or vice versa) comprises an additional phase called "transition zone," in which the characteristics of the particle suspension lay between those corresponding to pure clouds and atmospheric aerosols. This phase, however, is usually considered, in atmospheric monitoring and modeling, as an area containing either aerosol or thin clouds. A sensitivity analysis has been performed to assess the longwave radiative effects resulting from different approximations to the transition zone for three radiation parameterizations included in the Weather Research and Forecasting Model. The parameterizations produce important differences (up to 60 W m−2) between radiative effects of optically thin layers of aerosols and clouds (as surrogates for transition zone suspensions) in the longwave region, both at the top and bottom of the atmosphere. Also, differences are greater if the suspension of particles is located at higher altitudes, but smaller in high humidity conditions. Plain Language Summary: The change in the state of sky from cloudy to cloudless (or vice versa) comprises an additional phase called "transition zone," in which the characteristics of the particle suspension lay between those corresponding to a pure cloud and those of atmospheric aerosols. This phase, however, is usually considered, in atmospheric monitoring and modeling, as an area containing either aerosol or thin clouds. This study quantifies the uncertainties that this binary assumption may introduce to the estimation of longwave radiative effects at the top and bottom of the atmosphere by using the Fu‐Liou‐Gu (FLG), NewGoddard, and Rapid Radiative Transfer Model for General Circulation Model (RRTMG) radiative parameterizations included in the Weather Research and Forecasting Model. The results show that there are important differences between optically thin clouds and aerosols in longwave region, which may cause substantial uncertainties in the radiative effects at the top and bottom of the atmosphere (up to 60 W m−2) if they are used to approximate transition zone conditions. Results are important due to the role that longwave radiation plays in the radiative balance that drives the Earth's climate. Key Points: The LW radiation parameterizations RRTMG, FLG, and NGO included in WRF‐ARW were used for idealized one‐dimensional vertical simulationsDifferent approximations to transition zone cause substantial uncertainty in the LW radiative effects at top and bottom of the atmosphereNeglecting transition zone conditions at high altitudes contributes to larger uncertainties in the total column energy budget [ABSTRACT FROM AUTHOR]

This work reports on the analysis of structural and spectroscopic properties of the fluoroindate glasses co-doped with Er3+/Ho3+. Structural analysis showed that erbium and holmium ions were modifier ions and depolymerizedof the fluoroindate glass network. The energy transfer processes between rare - earth ions in fluoroindate glasses pumped by and 980 nm laser diode have been also examined. Due to partial Er3+ → Ho3+ energy transfer and superposition of Er3+: 4I 11/2 → 4I 13/2 (2.77 μm)+ Ho3+: 5I 6 → 5I 7 (2.85 μm) radiative transitions in fluoroindate glass co-doped with 0.8ErF 3 /1.6HoF 3 , a broadening 3 μm luminescence (Δλ= 201 nm) was obtained. The overall energy transfer efficiency η ET1 + η ET2 was calculated to be 95% indicating efficient sensitization of the holmium ions by erbium. [ABSTRACT FROM AUTHOR]

Aims. Accurate atomic data for Ti II are essential for abundance analyses in astronomical objects. The aim of this work is to provide accurate and extensive results of oscillator strengths and lifetimes for Ti II. Methods. The multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction (RCI) methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2018, were used in the present work. In the final RCI calculations, the transverse-photon (Breit) interaction, the vacuum polarisation, and the self-energy corrections were included. Results. Energy levels and transition data were calculated for the 99 lowest states in Ti II. Calculated excitation energies are found to be in good agreement with experimental data from the Atomic Spectra Database of the National Institute of Standards and Technology based on the study by Huldt et al. Lifetimes and transition data, for example, line strengths, weighted oscillator strengths, and transition probabilities for radiative electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) transitions, are given and extensively compared with the results from previous calculations and measurements, when available. The present theoretical results of the oscillator strengths are, overall, in better agreement with values from the experiments than the other theoretical predictions. The computed lifetimes of the odd states are in excellent agreement with the measured lifetimes. Finally, we suggest a relabelling of the 3d2(12D)4py2D3/2o 3 d 2 (2 1 D) 4 p y 2 D 3 / 2 o $ 3d^2(^{1}_{2}D)4p\,y^2D_{3/2}^{o} $ and z2P3/2o z 2 P 3 / 2 o $ z^2P_{3/2}^{o} $ levels. [ABSTRACT FROM AUTHOR]

Three new metal-organic framework polymers [Pb2(btdc)2] (1), [Pb3(ttdc)3(dma)2] (2), and [Pb(ttdc)(dma)] (3) (H2btdc = 2,2′-bithiophene-5,5′-dicarboxylic acid, H2ttdc = thieno[3,2-b]thiophene-2,5-dicarboxylic acid, dma = N,N-dimethylacetamide) are synthesized under solvatothermal conditions. The compounds are characterized by single crystal and powder X-ray diffraction, elemental, thermogravimetric, and IR spectroscopic analyses. All three compounds are three-dimensional coordination polymers with layered (1) or chain (2, 3) motifs. The study of luminescent properties reveals the intraligand nature of radiative transitions. For 1 luminescence quenching is observed because of the strengthening of vibrational states and long-range interactions between π-systems of thiophene groups. The luminescence spectrum of 2 contains two bands corresponding to two types of ttdc2– ligands with principally different structural environments. For the ligands isolated from each other the position of the luminescence maximum corresponds to that of the free ttdc2– ion. For the ligands associated in closely packed chains by continuous π-stacking the appearance of a new maximum in the red range is observed, which is due to the delocalization of electron orbitals. [ABSTRACT FROM AUTHOR]

With the recent advent of circular polarization capabilities at the Atacama Large Millimeter/submillimeter Array (ALMA), Zeeman effect measurements of spectral lines are now possible as a means to directly probe line-of-sight magnetic fields in protoplanetary disks (PPDs). We present a modeling study that aims to guide physical interpretation of these anticipated observations. Using a fiducial density structure based on a typical ringed disk, we simulate line emission for the hyperfine components of the CN J = 1−0 transition with the POLARIS radiative transfer code. Since the expected magnetic field and typical CN distribution in PPDs remain largely unconstrained, we produce models with several different configurations. Corresponding integrated Stokes I and V profiles and 0.4 km s−1 resolution, 1″ beam convolved channel maps are presented. We demonstrate that the emission signatures from toroidally dominated magnetic fields are distinguishable from vertically dominated magnetic field based on channel map morphology. Due to line-of-sight and beam cancellation effects, disks with toroidal -field configurations result in significantly diminished Stokes V emission. Complex magnetic fields therefore render the traditionally used method for inferring line-of-sight magnetic field strengths (i.e., fitting the derivative of the Stokes I to the Stokes V profile) ambiguous, since a given intrinsic field strength can yield a variety of Stokes V amplitudes depending on the magnetic field geometry. In addition, gas gaps can create structure in the integrated Stokes V profile that might mimic magnetic substructure. This method should therefore be applied with caution in PPD environments and can only confidently be used as a measure of magnetic field strength if the disk's magnetic field configuration is well understood. [ABSTRACT FROM AUTHOR]

We model the (v′ = 1, v″ = 0) band of the Birge–Hopfield I band system of molecular nitrogen, N2, i.e. , emitted by nonthermal gas discharges in low pressure air. In particular, we calculate the rate of electron impact excitation of N2, which is thermally equilibrated at room temperature, to rotational levels J′ < 31 of N2(b1Πu, v′ = 1, J′). Subsequently, we calculate the intensity of emission lines resulting from radiative transitions from the aforementioned rotational levels to. Predissociation is the only nonradiative channel considered for the decay of N2(b1Πu, v′ = 1, J′) levels. [ABSTRACT FROM AUTHOR]

The absolute quantum cutting efficiency of Tb3+-Yb3+ co-doped glass was quantitatively measured by an integrating sphere detection system, which is independent of the excitation power. As the Yb3+ concentration increases, the near infrared quantum efficiency exhibited an exponential growth with an upper limit of 13.5%, but the visible light efficiency was reduced rapidly. As a result, the total quantum efficiency monotonically decreases rather than increases as theory predicted. In fact, the absolute quantum efficiency was far less than the theoretical value due to the low radiative efficiency of Tb3+ (<61%) and significant cross-relaxation nonradiative loss between Yb3+ ions. [ABSTRACT FROM AUTHOR]

An efficient three-photon near-infrared (NIR) quantum cutting (QC) is reported in Tm3+ singly doped YVO4 polycrystalline phosphors, where an optimized content of Tm3+ is determined to be 1.0 mol. %. Upon the absorption of a visible photon around 473 nm, three NIR photons emitting at 1180, 1479, and 1800 nm can be obtained efficiently by the sequential three-step radiative transitions of Tm3+. The underlying mechanisms are analyzed in terms of the steady and dynamic fluorescence spectra measurements. Internal quantum yield is calculated to be 161.8% as a theoretical value when luminescence quenching due to defect species can be overcome. In addition, the broadband ultraviolet (UV)-excited [VO4]3- can strongly sensitize the 1G4 level of Tm3+ in the wavelength range likely from 250 to 360 nm, greatly increasing the UV photo-response and NIR fluorescent intensity of Tm3+. The further development of this broadband three-photon NIR QC material would explore the new route to improve the photo-response of novel photoelectronic devices, particularly in 250-360 nm. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (hBN) has become a prominent material for nanophotonic and quantum technology studies. Its wide bandgap can accommodate room temperature radiative optical transitions originating from defect states in different atomic structures. Here, we report the engineering of visible defects in chemical vapor deposited monolayer hBN irradiated by femtosecond pulses (0.1–0.5 W) at room temperature. Photoluminescence and transient photoluminescence measurements reveal the presence of a sharp emission at 630 nm with a time constant of approximately 3 ns randomly distributed around the irradiated region. We imaged the distribution of the photogenerated electrons by time-resolved photoemission electron microscopy in the picosecond and nanosecond timescales with 100 nm spatial resolution. We determined the precise location of the defects within the region of interest corresponding to an optical transition between 1.95 eV and 3.90 eV above the valence band maximum of hBN, ascribed to NBVN color centers. [ABSTRACT FROM AUTHOR]