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Nowadays, the application scenarios of rare earth doped luminescent materials tend to be refined and complicated. The optical properties of rare earth doped materials are difficult to precisely control via the traditional design and synthesis methods, namely, changing doping concentration or preparative conditions. The aim of this study is to tune the optical transition properties of Er3+ in tungsto-molybdate NaY(Mo x W 1- x O 4) 2 (x = 0, 0.01, 0.1, 0.3, 0.5, 0.7, 0.9, 0.99 and 1.0) phosphors by changing the host matrix. The Er3+ doped continuous tungsto-molybdate solid solution NaY(Mo x W 1- x O 4) 2 phosphors were prepared via a solid state reaction technique at optimized calcination temperatures. The refractive indexes of the obtained solid solution samples were confirmed according to different models and compared. Subsequently, the optical transition intensity parameters, radiative transition rates and intrinsic radiative lifetimes of Er3+ in these solid solution phosphors were calculated in the framework of Judd-Ofelt theory. It was confirmed that the optical transition properties of Er3+ can be greatly tuned by the solid solution composition, and the tuning effects for different transitions are different. To validate the reliability of the Judd-Ofelt calculations, the temperature-dependent emission spectra of two green emissions of Er3+ for different solid solution samples were studied. It was found that the radiative transition rate ratios between two green emissions derived from theoretical calculations and experimental measurements are in reasonable agreement, thus proving that the optical transition calculations are reliable and the optical transition properties of Er3+ in the tungsto-molybdates can be tuned in a large range. This work reminds us of a new route for developing novel luminescence materials based on practical demands. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive analysis of emission in erbium-doped and erbium and ytterbium co-doped fluoroindate glasses has been presented. The luminescence of the erbium transitions and the effect of ytterbium co-doping under 488, 808 and 976 nm laser excitation have been discussed. Optimization of rare-earth (RE) ions doping concentration and the energy transfer processes related to the sensibilization effect in Er3+/Yb3+ co-doped fluoroindate glasses focusing on the reciprocal distribution of radiative transitions, energy transfer parameters, and lifetimes have been analyzed. The luminescence consists of several bands in the visible (525, 546 and 660 nm) and the infrared (1550 and 2700 nm) spectral regions that correspond to characteristic radiative energy transitions within the erbium ions. In glasses co-doped with the Er3+/Yb3+ system, an augmentation in the emission intensity was observed in the visible and at 1550 nm, while a decrease was observed in the 2700 nm infrared band. The increase of the Yb3+: 2F 5/2 lifetime under 488, 808 and 976 nm excitation showed significant Er3+: 4I 11/2 → Yb3+: 2F 5/2 back energy transfer. Based on the analysis of the available literature, it can be concluded that energy transfer upconversion and cooperative energy upconversion play a significant role in modulating luminescence intensity values within the examined emission bands. This effect is likely enhanced due to the incorporation in a low phonon energy glass matrix. As a result of the above optimization, a glass optical fiber co-doped with 0.8 YbF 3 /1.4 ErF 3 (in mol%) was drawn and characterized, showing a strong emission at 2.77 μm. The optimized Er3+/Yb3+ co-doped fluoroindate glass and glass optical fiber confirmed their ability to be used in the visible and near-infrared spectral regions as efficient optical fiber sources. [ABSTRACT FROM AUTHOR]

The combustion method was used to synthesize Ce3+ doped LaB 3 O 6 phosphors in a range of dopant concentrations. Both the un-doped and Ce3+ doped LaB 3 O 6 samples matched the required reference card, according to X-ray diffraction patterns. TL glow curves of Ce3+ doped LaB 3 O 6 samples at various dopant concentrations were examined by employing various optical detection filter combinations to define TL characteristics. LaB 3 O 6 :Ce3+ (1%) and IRSL-TL 565 nm were selected as the suitable sample and appropriate detection filter pairing. The TL maximum with a higher intensity was seen during preheating trials (with 2 °Cs−1) at around 270 °C. The experimental results showed feasible linearity (R2 = 0.998 and b = 1.054) between 5 and 1000 Gy for the dose response of LaB 3 O 6 :Ce3+ (1%). The short-term fading test was conducted at various time intervals up to a week. The findings showed that the dosimetric peak strength was almost constant for up to 5 days. However, an additional spurious maximum appeared at the higher temperature zone. Each sample showed an abnormal heating rate effect, which can be explained by localized electrons caught in the intermediate excited state, which is capable of radiative transitions via the conduction band. To find the overlapping peak numbers and determine the kinetic parameters of preheated LaB 3 O 6 :Ce3+ (1%), various heating rates, T M - T s , initial rise, and computerized glow curve deconvolution techniques were utilized. The results suggest that LaB 3 O 6 :Ce3+ may be an appropriate material for TL dosimetry applications due to its efficient TL characteristics. [ABSTRACT FROM AUTHOR]

A novel vanadate host Ca2LiMg2V3O12 (CLMV) and the Eu3+‐doped samples were synthesized via a solid‐state reaction method. The phase formation and the morphological analysis were studied in detail. The Rietveld refinement result shows that the host belongs to cubic space group Ia‐3d (230) with lattice parameter, a = 12.3948 Å, V = 1904.23 Å3, and Z = 8. The diffuse reflectance spectroscopy measurement estimated the bandgap of the host and the CLMV:0.05Eu3+ phosphors. The host exhibits a broad absorption band (peak at 345 nm) ranging from 240 to 380 nm, which is attributed to the charge transfer in the O2−–V5+ complex. Under near UV excitation (λexc = 345 nm), the host gives a broad emission band covering the visible region from 400 to 730 nm and the emission is in the bluish–green region of the CIE diagram. When the host is doped with the Eu3+ ions and excited at 345 nm, the emission spectrum depicts the superimposition of the characteristic emission bands (red emission) of the Eu3+ ions corresponding to the f–f transitions over the broad emission band of the host. The calculated color coordinates (9600 to 2280 K) demonstrated the color tuning ability of the phosphor as the dopant concentration is increased in the host. This is because the VO43− group plays the sensitiser role and partially transfers energy with the Eu3+ ions. When the same set of phosphors were excited at the dominant characteristic excitation band (λexc = 394 nm) of the Eu3+, the characteristic emission bands of the Eu3+ in the orange–red region were observed. As the electric dipole transition of the Eu3+ was found to be dominant, the prepared phosphors possessed high color purity (CP). The energy transfer mechanism and the lifetime values were also presented. The temperature‐dependent PL studies showed good thermal stability of the optimum sample. Various radiative transition properties were analyzed by the Judd–Ofelt theory. The photometric results reveal the color tuning ability and CP of the CLMV:xEu3+ phosphors. [ABSTRACT FROM AUTHOR]

The article explores the photoluminescence properties of UV, near-UV and blue excited BaWO 4 : Eu3+ red phosphors. The optical band gap narrowing is observed after adding Eu3+ ions. The excitation spectra exhibit a broad peak centred at 255 nm and several narrow peaks of Eu3+ ions at 362, 382, 395, 415 and 465 nm. The three peaks located at 255 (UV), 395 (near-UV) and 465 nm (blue) are the most intense and suitable for the excitation of the sample. The spectral profile of the emission spectra irradiated at 255, 395 and 465 nm are identical. The brightest emission is realized at 18 mol% doping of Eu3+ ions at 255 and 465 nm excitations. However, the optimum concentration is 16 mol% at 395 nm excitation. The phosphors emit highly pure red lights with color purity 98.192%, 97.794% and 98.693% for the optimised concentration under UV, near-UV and blue excitations of 255, 395 and 465 nm, respectively. The quantum efficiency of BaWO 4 : 16 mol% Eu3+ phosphor is calculated as∼48.234% at 395 nm excitation. The emission intensity parameters are calculated in view of the Judd-Ofelt theory. The spectroscopic parameters like radiative transition probability, radiative lifetime, branching ratio and stimulated emission cross-section are further evaluated from the three emission spectra recorded at 255, 395 and 465 nm excitations. The derived results advocate the use of synthesized material as a red phosphor in white-LED, laser and display devices. [ABSTRACT FROM AUTHOR]

In this work, we evaluated the widths of the pionic and radiative transitions from the T c s ¯ 0 + (2900) to the D s 1 + (2460) in the D s 1 + (2460) molecular frame and the D s 1 + (2460) charmed-strange meson frame. Our estimations demonstrate that the transition widths in the D s 1 + (2460) molecular frame are much larger than those in the the D s 1 + (2460) charmed-strange meson frame. Specifically, the ratio of the widths of Γ (T c s ¯ 0 + (2900) → D s 1 + π 0) and Γ (T c s ¯ 0 + (2900) → D + (0) K 0 (+)) is estimated to be around 0.1 in the D s 1 + (2460) charmed-strange meson frame, whereas the lower limit of this ratio is 0.67 in the D s 1 + (2460) molecular frame. Thus, the aforementioned ratio could be employed as a tool for testing the nature of the D s 1 + (2460) . [ABSTRACT FROM AUTHOR]

Bioprobe based on fluorescence is widely used in biological and medical research due to its high sensitivity and selectivity. Yet, its quantification in vivo is complicated and often compromised by the interaction between the fluorophore with the environmental factors, as well as the optical scattering and absorption by the tissue. A high florescence quantum yield and minimal interference by the environment are key requirements for designing an effective bioprobe, and the pre-requisitions severely limit the available options. We propose that a comprehensive evaluation of potential bioprobe can be achieved by simultaneously measuring both radiative and non-radiative transitions, the two fundamental and complementary pathways for the energy de-excitation. This approach will not only improve the accuracy of the quantification by catching the information from a broader spectrum of the energy, but also provide additional information of the probe environment that often impacts the balance between the two forms of the energy transition. This work first analyzes the underlying mechanism of the hypothesis. The practical feasibility is then tested by means of simultaneous measurements of photoacoustic signal for the non-radiative and fluorescence for the radiative energy processes, respectively. It is demonstrated that the systematic evaluation of the probe energy de-excitation results in an improved quantitative tracing of a bioprobe in complex environment. [ABSTRACT FROM AUTHOR]

The NaGdF4:Nd3+@Ni core@shell nanoparticles were synthesized and characterized. First, core@shell nanoparticles were synthesized using a solvothermal method to obtain the NaGdF4:Nd3+ core with hexagonal phase; subsequently, a chemical reduction was performed to stimulate the growth of the Ni shell with cubic phase. NaGdF4:Nd3+@Ni nanoparticles were characterized by transmission electron microscope, zeta potential, X-ray diffraction, scattered energy spectroscopy, UV-Vis, and photoluminescence emission spectra. The nanoparticles were round in shape, with mean sizes around 250 nm. The core@shell nanoparticles presented a homogenous composition and good stability. The photoluminescent emission of the nanoparticles was recorded at 1059 nm in the near-infrared spectral range; this band corresponds to the 4F3/2→4I11/2 radiative transitions of Nd3+ ions. The synthesized nanoparticles, being hydrophilic, have potential for use in different areas, one of them could be in anaerobic digestion. [ABSTRACT FROM AUTHOR]

The fluorophores in the second near‐infrared (NIR‐II) biological window (1000 – 1700 nm) show great application prospects in the fields of biology and optical communications. However, both excellent radiative transition and nonradiative transition cannot be achieved simultaneously for the majority of traditional fluorophores. Herein, tunable nanoparticles formulated with aggregation‐induced emission (AIE) heater are developed rationally. The system can be implemented via the development of an ideal synergistic system that can not only produce photothermal from nonspecific triggers but also trigger carbon radical release. Once accumulating in tumors and subsequently being irradiated with 808 nm laser, the nanoparticles (NMB@NPs) encapsulated with NMDPA‐MT‐BBTD (NMB) are splitted due to the photothermal effect of NMB, leading to the decomposition of azo bonds in the nanoparticle matrix to generate carbon radical. Accompanied by second near‐infrared (NIR‐II) window emission from the NMB, fluorescence image‐guided thermodynamic therapy (TDT) and photothermal therapy (PTT) which significantly inhibited the growth of oral cancer and negligible systemic toxicity is achieved synergistically. Taken together, this AIE luminogens‐based synergistic photothermal‐thermodynamic strategy brings a new insight into the design of superior versatile fluorescent NPs for precise biomedical applications and holds great promise to enhance the therapeutic efficacy of cancer therapy. [ABSTRACT FROM AUTHOR]

In this study, the optical and structural properties of carbon dots (CDs) synthesized using a hydrothermal method were investigated. CDs were prepared from various precursors such as citric acid (CA), glucose, and birch bark soot. The SEM and AFM results show that the CDs are disc-shaped nanoparticles with dimensions of ~7 nm × 2 nm for CDs from CA, ~11 nm × 4 nm for CDs from glucose, and ~16 nm × 6 nm for CDs from soot. The TEM images of CDs from CA showed stripes with a distance of 0.34 nm between them. We assumed that the CDs synthesized from CA and glucose consisted of graphene nanoplates located perpendicular to the disc plane. The synthesized CDs contain oxygen (hydroxyl, carboxyl, carbonyl) and nitrogen (amino, nitro) functional groups. CDs have strong absorption in the ultraviolet region in the range of 200–300 nm. All CDs synthesized from different precursors displayed bright luminescence in the blue-green region of the spectrum (420–565 nm). We found that the luminescence of CDs depended on the synthesis time and type of precursors. The results show that the radiative transitions of electrons occur from two levels with energies ~3.0 eV and ~2.6 eV, which are due to the presence of functional groups. [ABSTRACT FROM AUTHOR]

Tellurite glasses doped with Tm3+, Ho3+ and Ce3+ ions were prepared via melt-quenching to realise broadband and fluorescence enhancement in near-infrared (NIR) band. Under the pumping of a commercial 808 nm laser diode (LD), the emission bands at 2.0 μm, 1.85 μm, 1.47 μm, and 705 nm were observed in the Tm3+/Ho3+ co-doping glass samples, which originated from the transitions of Ho3+:5I 7 →5I 8 and Tm3+:3F 4 →3H 6 , 3H 4 →3F 4 , 3F 2,3 → 3H 6 , respectively. The existence of 2.0 μm band fluorescence is due to the energy transfer from the Tm3+:3F 4 level to the Ho3+:5I 7 level. This band overlaps with the 1.85 μm band which forms a broadband fluorescence spectrum in the range of 1600–2200 nm. In glass samples co-doped with Tm3+/Ho3+ with 0.085 mol% Ho 2 O 3 and 1 mol% Tm 2 O 3 , the full width at half maximum (FWHM) of this broadband spectrum (1600–2200 nm) was as high as ∼370 nm. After introducing 0.6 mol% CeO 2 , the emission intensity of broadband fluorescence increased by ∼50%, which was caused by the cross-relaxations between Ce3+ and Tm3+ ions. The lifetime of fluorescence decay was determined to prove the interactions among the doped rare-earth ions, the radiative parameters such as transition probability, branching ratio and radiative lifetime were calculated from the absorption spectra based on the Judd-Ofelt theory to better understand the observed luminescence phenomena. In addition, X-ray diffraction (XRD) confirmed the amorphous state structure of the synthesised glass samples, while Raman spectrum revealed the different vibrational structural units forming the glass network. [ABSTRACT FROM AUTHOR]

A series of Eu3+ and Eu3+/Gd3+ co-doped barium-bismuth-borate (Ba–Bi–B) glasses were prepared by melt-quench technique. And deliberated the physical, structural, and spectroscopic properties of all glasses and explored the energy transfer process from Gd3+ to Eu3+ ions. The density of glasses increased with increasing of Gd3+ concentration in co-doped glasses. Characteristics of steady-state and time-resolved photoluminescence (PL) of Eu-doped and Eu3+-Gd3+ co-doped glasses under different excitation wavelengths suggested the prospects of the investigated glass system for display device applications. PL spectrum displays a strong red emission peak centered at 612 nm due to the Eu3+: 5D 0 → 7F 2 transition. Less intense emissions centered at 577 nm (7F 0), 590 nm (7F 1), 651 nm (7F 3) and 700 nm (7F 4) are also observed from the radiative transitions of the excited state 5D 0 of Eu3+ions. The values of radiative parameters such as transition probability, branching ratios, and stimulated emission cross-sections were obtained from Judd–Ofelt theory analysis and indicated the aptness of the Ba–Bi–B glasses for optical devices. A 5-fold enhancement in the PL intensity was observed in 1.0 mol% Eu3+ and 3.0 mol% Gd3+ co-doped glass under λ Exci. = 394 nm excitation. The calculated commission Internationale de l'eclairage color coordinates and correlated color temperature values show that the Ba–Bi–B glasses are useful for red-laser and display device applications. [ABSTRACT FROM AUTHOR]

Dye lasers are commonly used in optical investigation because their solutions in organic solvents deliver tunable, coherent emissions. They exhibit intense fluorescence owing to some specific spectroscopic characteristics. One drawback of the laser dyes is that it shows excessive triplet-state losses (TSLs.) The lack of theoretical predictions of fluorescence rates, intersystem crossing (ISC), and phosphorescence in laser dyes prompted us to report on the predicted rates of radiative and nonradiative transitions of some laser dyes. Structural engineering by some substituents influencing the simulated rates of coumarin laser dye derivatives for an efficient operation was investigated. The NH2 functional group renders the coumarin 120 more fluorescents with reduced TLS than the other investigated materials. Tailoring new efficient laser dyes can be achieved guided by the calculated rates of emission and nonradiative processes. [ABSTRACT FROM AUTHOR]

The photoluminescence of Au(I) complexes is generally characterized by long radiative lifetimes owing to the large spin-orbital coupling constant of the Au(I) ion. Herein, we report three brightly emissive Au(I) coordination compounds, 1, 2a, and 2b, that reveal unexpectedly short emission lifetimes of 10–20 ns. Polymorphs 2a and 2b exclusively exhibit fluorescence, which is quite rare for Au(I) compounds, while compound 1 reveals fluorescence as the major radiative pathway, and a minor contribution of a microsecond-scale component. The fluorescent behaviour for 1–2 is rationalized by means of quantum chemical (TD)-DFT calculations, which reveal the following: (1) S0–S1 and S0–T1 transitions mainly exhibit an intraligand nature. (2) The calculated spin-orbital coupling (SOC) between the states is small, which is a consequence of overall small metal contribution to the frontier orbitals. (3) The T1 state features much lower energy than the S1 state (by ca. 7000 cm−1), which hinders the SOC between the states. Thus, the S1 state decays in the form of fluorescence, rather than couples with T1. In the specific case of complex 1, the potential energy surfaces for the S1 and T2 states intersect, while the vibrationally resolved S1–S0 and T2–S0 calculated radiative transitions show substantial overlap. Thus, the microsecond-scale component for complex 1 can stem from the coupling between the S1 and T2 states. [ABSTRACT FROM AUTHOR]

ZnO–P 2 O 5 glasses activated with Ag m n + clusters and Mn2+ ions were successfully synthetized by the melt-quenching method. X-ray diffraction patterns confirmed the glassy nature for doping concentrations up to 3.0 and 5.0 mol% of Ag+ and Mn2+ ions, respectively, whereas the Raman spectra in all cases displayed δ(P–O–P), ν s (P–O–P), ν s (PO 2) and ν as (PO 2) vibrational modes, typical of a phosphate glass network. The emission spectra under 345 nm (Ag m n + : S 0 → S 1 and Mn2+: 6A 1 (S) → 4T 1 (P) + 4E(D)), 385 nm (Ag m n + : S 0 → S 1) and 407 nm (Mn2+: 6A 1 (S) → 4A 1 (G) + 4E(G) and Ag m n + : S 0 → S 1) excitations, showed the broad band related to the superimposed Ag m n + cluster: S 1 → S 0 , T 2 → S 0 and T 1 → S 0 radiative transitions along with the Mn2+: 4T 1 (G) → 6A 1 (S) one. Under 385 nm excitation, the Mn2+ emission transition is attained by energy transfer from Ag m n + clusters. Such excitations lead to emission tonalities in the bluish white to cold white (345 and 385 nm) and cold white to reddish orange (407 nm) ranges, with correlated color temperature (CCT) values in the 10,095-5371 K (345 nm), 14,768-6862 K (385 nm) and 8592-1633 K (407 nm) ranges. Purplish pink emissions upon 345 nm excitation were obtained as well. The white color tonalities together with the color rendering index (CRI) and absolute quantum yield (QY, external) values up to 95 Ra and 35%, respectively, revealed promissory features for rare-earth-free white light emitting diode applications. The Ag m n + cluster: S 1 → S 0 emission fitting by the Burstein model suggested that the non-radiative energy transfer is mainly mediated by an electric dipole-dipole interaction. [ABSTRACT FROM AUTHOR]

Novel ternary fluoro-germano-tellurite (GTS) glasses doped with Er3+ ions with 0.5 mol% and 1.0 mol% were fabricated by a conventional melt and quenching method and investigated using methods of optical spectroscopy. The room-temperature absorption spectrum was recorded and analyzed to determine radiative transition rates, radiative lifetimes, and branching ratios of Er3+ luminescence. Decay curves of Er3+ luminesccence were recorded and analyzed. Temperature dependences of emission spectra and absorption spectra in the region from RT (room-temperature) up to 675 K were studied in detail. The contribution of competing radiative and nonradiative processes to the relaxation of luminescent levels of Er3+ was assessed. Absolute and relative sensitivity were established utilizing the comprehensive model based on thermally coupled 2H11/2/4S3/2 excited states of erbium. The high quantum efficiency of the first erbium-excited state and value of gain coefficient indicate that GTS:Er glass system can be considered as conceivable NIR (near infrared) laser material as well. [ABSTRACT FROM AUTHOR]

In the optical energy gap, visible and near-IR emission of halide phosphate glasses with a composition of 40P2O5-30ZnO-20LiCl-10BaF2 in mol% doped with 3.5 × 104 ppm Pr2O3, referred to as PZLBPr, were synthesized. The UV-VIS-NIR and spectroscopic properties of these glasses were also predicted. The current glasses had broadband emission photoluminescence covering a wavelength range of 1250 to 1700 nm when excited at 455 nm. These bands for near-infrared emission luminescence relate to the transitions 1G4 → 3H5, 1D2 → 1G4, and 3H4 → 3F3, 3F4 in the optical telecommunication window. The significant PL emission wideband was caused by the radiative transition from Pr3+: 1D2 to 1G4. At 445 nm excitation, these glasses exhibited emission bands that corresponded to blue/reddish orange spectral ranges in visible ranges. The prepared glass has a high lasing quality factor (Ω4/Ω6 = 0.9), high optical energy (4.72 eV), and quantum efficiency = 87.3% with FWHM = 156 nm of transition emission from the 1D2 → 1G4 level. As a result, broadband near infrared optical amplifiers can be fabricated from the prepared glasses. [ABSTRACT FROM AUTHOR]

The role is considered of all known potential sources of excitation of the 1D term of atomic oxygen in auroras and the value of their relative contributions to the emission intensity of 630.0-nm emission in the height interval of 100−300 km. The main attention is paid to the role of weak excitation sources of 1D terms, such as collisional interactions between the components of atmospheric gases N(2D) + O, N(2D) + O2,N(2P) + O2, and N+ + O2; direct electron impact O2 + e*; and the radiative transition O(1S) → O(1D) + hν557.7. It is shown that, despite the small partial contributions of these sources to the intensity of the 630.0-nm emission, their total contribution can be quite significant. The total efficiency of these sources varies from 66 to 6% with an increase in altitude from 100 to 300 km and is significant at altitudes below 200 km. It is shown that the influence of the decontamination process leads to the fact that, in the region of heights of ∼110−150 km, the set of reactions of collisional interactions of ionospheric plasma components N(2D) + O, N(2D) + O2,N(2P) + O2, and N+ + O2 becomes the second most efficient source contributing to the intensity of the 630.0-nm emission. [ABSTRACT FROM AUTHOR]

Ram pressure stripping (RPS) is a process that removes the interstellar medium (ISM) quickly, playing a vital role in galaxy evolution. Previous RPS studies have treated the ISM as single-phase or lack the resolution and physical processes to properly capture the full multiphase ISM. To improve this simplification, we introduce an inflowing, hot intracluster medium (ICM) into a self-consistently modeled ISM in a local patch of star-forming galactic disks using the TIGRESS framework. Our simulations reveal that the workings of RPS are not only direct acceleration of the ISM by ICM ram pressure but also mixing-driven momentum transfer involving significant phase transition and radiative cooling. The hot ICM passes through the low-density channels of the porous, multiphase ISM; shreds the cool ISM; and creates mixing layers. The ICM momentum is transferred through the mixing layers while populating the intermediate-temperature gas and radiating thermal energy away. The mixed gas extends beyond galactic disks and forms stripped tails that cool back unless the ICM fluxes are large enough to prevent cooling until they escape the simulation domain. The mixing-driven momentum transfer predicts that the more ICM mixes in, the faster the ISM moves, resulting in the anticorrelation of outflow velocity and gas metallicity of the stripped ISM. The compression of the ISM disks due to the ICM ram pressure enhances star formation rates up to 50% compared to the model without ICM. With the ICM ram pressure higher than the disk anchoring pressure, star formation is quenched within ∼100 Myr. [ABSTRACT FROM AUTHOR]

We report a comparative study of coordination behaviour of 2-(2-aminophenyl)benzothiazole (NH2-pbt) and its phosphorus-containing derivative, α-aminophosphine oxide (PCNH-pbt), towards zinc halides. The corresponding coordination compounds [Zn(L)2Hal2] (L = PCNH-pbt, Hal = Cl, 1 and Hal = Br, 2) and [Zn(L')Hal2] (L' = NH2-pbt, Hal = Cl, 3 and Hal = Br, 4) were obtained as single phases. As evidenced by single-crystal X-ray diffraction analysis, L' ligand coordinates to Zn in a chelate manner via two N atoms. Despite a similar coordination mode in complexes 3 and 4, the spatial geometry of the ligand differs notably, which implies a relatively high flexibility of NH2-pbt. The L ligand exhibits another coordination mode, binding with Zn only via the oxygen of the P=O group. The differences in the structures of NH2-pbt, 3 and 4, and their counterparts, PCNH-pbt, 1 and 2, induce differences in their solid-state photoluminescence properties. The former group of the compounds exhibits conventional single-band emission, while the latter group reveals two bands. The minor band at 450 nm is ascribed to a radiative transition for the regular amine species, while the major band at 520–550 nm can be associated either with the proton-transferred imine species (ESIPT mechanism) or with a charge transfer state (TICT) with a different geometry. [ABSTRACT FROM AUTHOR]

Results of experimental and theoretical investigations into the electron-impact excitation of the resonance 6 s 6 p 1 P 1 ° â†' 6 s 21 S 0 (132.2 nm), as well as the cascade 6 s 7 s 1 S 0 â†' 6 s 6 p 1 P 1 ° (309.2 nm) and 6 p 21 D 2 â†' 6 s 6 p 1 P 1 ° (150.8 nm) spectral transitions from the ground 6 s 21 S 0 level in the thallium ion, are presented. Crossed beams of electrons and Tl+ ions in combination with a spectroscopic method were used in the experiment. Measured cross sections have a distinct resonance structure arising mainly from the electron decay of atomic 5 d 96 s 26 p 2, 5 d 106 s 7 s (1 S) np (n â©ľ 7), 5 d 106 s 6 d (1 D) np (n â©ľ 6), 5 d 106 s 6 d (1 D) nd (n â©ľ 6) and ionic 5 d 96 s 2 np, 5 d 96 s 2 nd, 5 d 96 snp (n â©ľ 6) autoionizing levels, as well as radiative transitions from the higher 6 s 7 s 1 S 0, 6 s 6 d 1 D 2, and 6 p 21 D 2, 1 S 0 ionic levels. Relativistic distorted wave (RDW) calculations are performed to obtain the effective cross sections for the above transitions. The absolute values of the cross sections are found to be 1.39 Ă— 10âˆ'16 cm2 at 300 eV for the λ 132.2 nm resonance line, and 0.11 Ă— 10âˆ'16 cm2 and 0.56 Ă— 10âˆ'16 cm2 at 100 eV for the λ 309.2 nm and λ 150.8 nm lines, respectively. The contribution of the cascade transitions being studied to the effective cross section of the λ 132.2 nm resonance line at the energy of 100 eV is about 30%. A calculation using the semi-empirical Van Regemorter formula is also performed to obtain the effective cross section of the resonance λ 132.2 nm line. The absolute value of the cross section at 300 eV is found to be nearly the same as that given by the RDW calculation. [ABSTRACT FROM AUTHOR]

A high-luminescent, blue-light excitable europium(III) coordination complex, [Eu(µ2-OC2H5)(btfa)(NO3)(phen)]2phen (1) {btfa = benzoyl trifluoroacetone, phen = 1,10-phenantroline}, has been synthesized and investigated. The complex was characterized by infrared (IR) and photoluminescence (PL) spectroscopy. The PL emission spectra of powder samples registered in a range of 10.7–300 K exhibit characteristic metal-centered luminescence bands, assigned to internal radiative transitions of the Eu3+ ion, 5D1→7Fj and 5D0→7Fj (j = 0–4). The high-resolution spectrum of the transition 5D0→7F0 shows that it consists of two narrow components, separated by 0.96 meV, which indicates the presence in the matrix of two different sites of the Eu3+ ion. The splitting pattern of 5D0→7Fj (j = 0–4) transitions indicates that europium ions are located in a low-symmetry environment. The absolute quantum yield and the sensitization efficiency were determined to be 49.2% and 89.3%, respectively. The complex can be excited with low-cost lasers at around 405 nm and is attractive for potential applications in optoelectronics and biochemistry. [ABSTRACT FROM AUTHOR]

Solution-processed polymer light emitting devices (PLEDs) using high-quality thermally activated delayed fluorescence (TADF) polymers as the emitting layers are attractive, however, high-efficiency white-light TADF polymers are very rare because of the complicated radiative transition channels. In this study, a series of hyperbranched TADF conjugated polymers were designed and synthesized which adopted the linear D-A-type TADF emitter of 1,8-naphthalimide-acridine as red chromophores, conjugated poly(fluorene-carbazole) as the blue backbone and triphenylamine as the hyperbranched cores. By adjusting the appropriate feed ratios of monomers, energy transfer process from the blue backbone to the red chromophores could be regulated and HR0.8 film had the highest photoluminescent quantum yield of 24 %. Consequently, its doped electroluminescent device showed the cold-white emission with the CIE color coordinates of (0.35, 0.23) and the maximum EQE of 6.82 %. By simply raising the concentration of the red chromophore in the polymers, the rapid reverse intersystem crossing (RISC) process and the enlarged energy gap between S 1 and T 1 were achievable. [Display omitted] • A series of hyperbranched conjugated polymers with excellent TADF character were designed and synthesized. • By raising the concentration of red chromophores, the reverse intersystem crossing rates was improved. • All polymers had flat and smooth film morphologies. • HR0.8 devices showed the best white light with a CIE coordinate of (0.35, 0.23) and the maximum EQE of 6.82%. [ABSTRACT FROM AUTHOR]

Herein, a new electrochemiluminescence (ECL) biosensor was constructed with highly efficient polymerized carbon dots (PCDs) as ECL emitter and the improved localized catalytic hairpin assembly (L-CHA) as signal amplifier for ultrasensitive detection of microRNA-222 (miRNA-222). Impressively, compared to the traditional carbon dots with inefficient blue region ECL emission, PCDs with N, O co-dope and large conjugated π-system showed high electrical conductivity, narrow band gap and strong radiative transition, which could exhibit high ECL efficiency to improve the sensitivity of detection and long wavelength ECL emission to achieve deep tissue penetration for reducing biological damage. Furthermore, the trace target miRNA-222 could be efficiently converted into large amounts of output DNA labelled with the quencher dopamine (S-DA) through the L-CHA reaction to significantly enhance the target amplification efficiency for further improving the sensitivity of detection. Thus, the ECL biosensor could achieve the ultrasensitive detection of miRNA-222 from 100 aM to 100 pM with the detection limit of 76 aM. Therefore, this work proposed a novel CDs with high ECL efficiency and long wavelength ECL emission, which not only was used to build an ultrasensitive biosensor for biomolecules detection in clinical diagnosis, but also served as a potential emitter for ECL bioimaging. [ABSTRACT FROM AUTHOR]

Based on the local surface plasmon resonance effect of Ag nanolayer, the luminescence enhancement in the visible light range of multilayer thin film has been investigated combined with metal/spacer molecule/photoluminescence material structure. The luminescence enhancement effect of multilayer thin films can be improved by adjusting the spin-coating number of Ag nanolayer and SiO 2 spacer in the multilayer structure. At the same time, the mechanism of enhanced luminescence has been analyzed according to the change in fluorescence lifetime. The effect of the coupling between Ag nanolayer and luminescence layer on the radiative transition rate and fluorescence quantum yield have been discussed. The up-conversion luminescence intensity of the noble metal-modified multilayer thin film can be further improved by combining the multilayer structure with sensitized layer. • The emission intensity of thin films are improved via the LSPR effect of Ag nanolayer. • On the basis of Ag@Tm/Yb structure, SiO 2 spacer layer is introduced to further enhance the upconversion luminescence. • The mechanisms of luminescence enhancement in the multilayer thin films are analyzed. • More than 20 times emission enhancement is achieved in the Ag@SiO 2 @Tm/Yb@Yb multilayer thin films. [ABSTRACT FROM AUTHOR]

[Display omitted] • QY was improved without changing the fluorescence wavelength by catalysis of MnSO 4. • The C = N and pyridine N could suppress k NR , leading to the QY increasement. • Warm white LED with excellent performance was constructed by using muticolor CDs. Multicolor carbon dots (CDs) possess tremendous potential applications, especially in optoelectronic devices. However, further applications in warm white LED have been constrained due to the extremely low quantum yield (QY) of multicolor CDs. In this work, fluorescence enhancement multicolor CDs (o-CDs(cat.) (emitted yellow, Em = 550 nm, QY = 85.4 %), m-CDs(cat.) (emitted blue, Em = 440 nm, QY = 35.7 %), p-CDs(cat.) (emitted red, Em = 610 nm, QY = 73.8 %)) with almost 15 % QY improvement, without changing the fluorescence emission wavelength, was successfully achieved by introducing MnSO 4 into the reaction system. The relevant mechanism may be the catalytic effect of MnSO 4 , which leads to the increased content of C = N and pyridine N, further suppressing non radiative transitions, leading to the increasement of QY. Finally, the obtained high QY multicolor CDs were applied to warm white LED with the color coordinates (CIE) of (0.33,0.36), color rendering index (CRI) of 90, correlated color temperature (CCT) of 3473 K. Laying the foundation for the research methods and mechanisms of metal ion caused high QY of CDs. [ABSTRACT FROM AUTHOR]

An explicit realistic model featuring a supercooled phase transition, which allows us to explain the background of gravitational waves recently detected by pulsar timing arrays, is constructed. In this model the phase transition corresponds to radiative symmetry breaking (and mass generation) in a dark sector featuring a dark photon associated with the broken symmetry. The completion of the transition is ensured by a non-minimal coupling between gravity and the order parameter and fast reheating occurs thanks to a preheating phase. Finally, it is also shown that the model leads to primordial black hole production. [ABSTRACT FROM AUTHOR]

In this study, a series of well-crystallized Yb3+/Er3+/Tm3+-tridoped Y2O3-ZnO ceramic nano-phosphors were prepared using sol–gel synthesis, and the phosphor structures were studied using X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The phosphors were well crystallized and exhibited a sharp-edged angular crystal structure and mesoporous structure consisting of 270 nm nano-particles. All phosphors generated blue, green, and red emission bands attributed to Tm: 1G4→3H6, Er: 2H11/2 (4S3/2)→4I15/2, and Er: 4F9/2→4I15/2 radiative transitions, respectively. Increasing in luminescent centers, weakening of lattice symmetry, and releasing of dormant rare earth ions can enhance all emissions. Er3+ can obtain energy from Tm3+ to enhance green and red emission. These colors can be tuned by optimizing the doping concentrations of the Er3+ ion. The color coordinates were adjusted by tuning both the Er3+ concentration and excitation laser pump power to shift the color coordinates and correlated color temperature. The findings of this study will broaden the potential practical applications of phosphors. [ABSTRACT FROM AUTHOR]

We briefly discuss the history of pumping schemes for the common 22-GHz maser transition in o-H2O, and note that radiative mechanisms have been considered in the past, as well as the better known collisional pumping mechanisms associated with shock waves. Substantial IR irradiation is indeed destructive to inversion at 22-GHz under a wide range of physical conditions. We identify a small number of transitions, including 22 GHz, that can be pumped by both collisional and radiative schemes, and, through radiative transfer modelling over a grid of values in kinetic temperature, number density, and dust temperature, identify loci in density-kinetic temperature space where these schemes lead to strong inversions. The radiative pumping scheme generally operates at higher dust temperature, and lower kinetic temperature, than the collisional scheme. We identify a small network of transitions that form a radiative pumping scheme for the 22-GHz maser, involving radiative transitions of wavelength approximately 6  |$\mu$| m. This network is capable of supplying more than 50 per cent of the 22-GHz inversion under typical radiative pumping conditions, and it is consistent with the need for high dust and low kinetic temperatures determined from the modelling. We identify a probable case of radiative pumping in a massive star-forming region from the observation of a positive correlation between the flux densities of 22-GHz H2O masers and 6.7-GHz methanol masers. We discuss possibilities for finding radiatively pumped H2O maser lines in other source types. [ABSTRACT FROM AUTHOR]

The Si2C and SiC2 both are considered to play key role in the formation of the SiC dust grains in the atmosphere of the carbon-rich stars. The molecule of our interest Si2C has been detected in the envelope of the red supergiant star IRC+10216 first time. It is an asymmetric top molecule having electric dipole moment of 1 Debye along the b-axis of inertia. Because of zero nuclear spin of both the Carbon and Silicon atoms, it has only paratransitions. Using the given spectroscopic data (rotational and centrifugal distortion constants and electric dipole moment), for the para-Si2C, we have calculated energies of 200 lower rotational levels (having energy up to 217.8 cm-1) and the Einstein A and B coefficients for 867 radiative transitions between the levels. We have solved a set of 200 statistical equilibrium equations coupled with 867 equations of radiative transfer (Sobolev analysis), where the collisional rate coefficients are taken from a scaling law. Out of 867 radiative transitions, 13 transitions have been found showing weak MASER action, and 19 transitions showing anomalous absorption. One transition 808-717 is found to show both the MASER action as well as the anomalous absorption. These transitions in addition to the observed transitions may play important role in the identification of Si2C in the cosmic objects. [ABSTRACT FROM AUTHOR]

The population of the 2 s -level of hydrogen formed in the early Universe is studied within a standard and a non-standard quasi-molecular mechanism of recombination. We demonstrate that, if hydrogen molecular ion |$H_2^+$| temporarily formed during a collision directly dissociates into a hydrogen atom and a proton, both mechanisms of recombination lead to the same probabilities of population. These probabilities differ significantly, however, when attractive quasi-molecular channels are uninvolved and only repulsive channels remain in the treatment. The probabilities of the direct and indirect radiative transitions into the 2 s -level of hydrogen are evaluated. The dominant process in the population of 2 s -level of hydrogen is the direct free–bound radiative transition. [ABSTRACT FROM AUTHOR]

Methylene is an important astrochemical compound. Though its laboratory spectrum was analyzed in 1982, its first unambiguous detection could be feasible after more than one decade in the hot core of Orion-KL nebula and the approximate molecular cloud of the continuum source W51M through its emission line 404-313. Since then waiting of its further detection has now broken as it has been detected in W51 E, W51 M, W51 N, W49 N, W43, W75 N, DR21, and S140 star forming regions, and in W3 IRS5 through the same transition 404-313. To find potential lines of methylene, we have performed Sobolev LVG analysis of each of the ortho and para species of methylene, considering 10 rotational levels having energy up to 324 cm-1. We have found only three lines, 404-313, 505-414 and 212-303 of methylene, which may help for its detection in a cosmic object. The line 212-303 lying at the lowest energy may be more helpful in a cosmic object having low kinetic temperature. [ABSTRACT FROM AUTHOR]

In our recent papers, a non-standard quasi-molecular mechanism was suggested and applied to treat the cosmological recombination. It was assumed that, in the pre-recombination stage of evolution of the Universe, an electron combined with two neighbouring protons and created a hydrogen molecular ion, |$\mathrm{ H}_2^+$| in a highly excited state, which then descended into the lower lying state or dissociated. In this work, we implement a quantitative analysis of this quasi-molecular mechanism of recombination; namely, we elaborate the scheme of calculation for a free–bound radiative transition. We show that the quasi-molecular mechanism played a significant role in the pre-recombination and recombination stages of evolution of the early Universe, and hence must be included into the consideration of the description of a thermal history of the Universe. Together with the earlier developed treatment of bound–bound radiative transitions in |$\mathrm{ H}_2^+$|⁠ , the elaborated scheme of calculation can be used for the design of a rapid and complete cosmological recombination code. [ABSTRACT FROM AUTHOR]

Recently, there have been significant interest in the wide potential of photoluminescence (PL) response of rare-earth doped perovskite oxide thin films in the field of optoelectronics. This work reports an effective method to modulate the PL properties of 0.8 mol%Sm3+-doped BaTiO 3 (BTO:Sm) thin films through static and dynamic strain. BTO:Sm films were epitaxially grown on LaAlO 3 (LAO), 0.7Pb(Mg 1/3 Nb 2/3)O 3 -0.3PbTiO 3 (PMN-PT), MgO, and Mica single-crystal substrates by pulsed laser deposition technique. Compared with the BTO:Sm/PMN-PT heterostructure which experiences minimal lattice mismatch effect, the PL intensity of BTO:Sm/LAO and BTO:Sm/MgO is enhanced by 818.1% and 1014.7%, respectively, due to static tensile/compressive strain (-0.429% and 0.461%) during the epitaxial growth process. In the flexible BTO:Sm/Mica heterostructure, dynamic strain is introduced through mechanical bending. Compared with the unbent state, the u-type and n-type bending modes increase the relative changes in PL intensity (Δ I / I) by 599.0% and 768.5%, respectively. Particularly, BTO:Sm/Mica also exhibits a remarkable optical transmittance exceeding 75% (500–2500 nm). The enhancement of PL intensity is closely related to the adjustment of lattice strain, which changes the crystal field strength of the BTO:Sm and the radiative transition probability. This work provides valuable insights for designing future optoelectronic devices and environmental monitoring equipment. It has the potential to advance photonics and sensor technologies, paving the way for innovation and exploration in these fields. • The enhancement of PL intensity in BTO:Sm thin films is achieved through static strain. • High-quality BTO:Sm thin film with high transmittance and low roughness is epitaxially grown on Mica substrates. • Dynamic tuning of the PL behavior in BTO:Sm thin film is achieved by applying bending induced dynamic strain. [ABSTRACT FROM AUTHOR]

To examine the influence of radiative transitions on the performance of nonequilibrium seed-free argon plasma magnetohydrodynamic (MHD) generators, we developed MHD numerical simulation technique with a collisional-radiative (C-R) model, where neutral argon atoms with 45 discrete effective electronic excitation levels, singly ionized argon ions, and free electrons were considered under a two-temperature, low-magnetic Reynolds number MHD approximation. Furthermore, a so-called escape factor was implemented in the C-R model to consider the effects of radiation trapping by ground-state neutral atoms. Using the developed technique, we computed the performance characteristics of a nonequilibrium seed-free argon plasma MHD generator. The numerical results showed that the generator performance gets higher as the escape factor decreases, i.e., the optical thickness for radiative transitions to the ground state of neutral atoms increases. The numerical results also suggested that when the escape factor is $1.0\times 10^{-3}$ or less, the generator performance is almost the same as that for the escape factor of 0 corresponding to completely optical-thick plasma case for the radiative transitions to the ground state of neutral atoms. Furthermore, realistic escape factor values for resonance lines in the power generation channel were evaluated using a well-known estimation model. Consequently, the estimated values had the order of $10^{-4}$. We also showed that under such relatively optically thick plasma cases, a collisional (C) model and a widely used global ionization-recombination rate model with no explicit consideration of electronically excited-state neutral atoms can reproduce the generator performance predicted by the C-R model with relatively good accuracy. [ABSTRACT FROM AUTHOR]

Aminomethanol (NH2CH2OH) and N-Methylhydroxylamine (CH3NHOH) are isomers of each other, and have astrochemical importance. To our knowledge, they have not been analyzed so far in any terrestrial laboratory, and probably due to non-availability of accurate frequencies, they have not been searched in a cosmic object. It is well known that physical conditions in cosmic objects are very different as compared to those in our terrestrial laboratories. Therefore, these molecules may exist in the interstellar medium. For having information about the potential spectral lines of these molecules, we have obtained their rotational and centrifugal distortion constants, and electric dipole moment with the help of the GAUSSIAN software using B3LYP method, and aug-cc-pVDZ and aug-cc-pVTZ basis sets, separately. As the electric dipole moment has comparable components along all the three a, b and c axes, we have considered all the three types of radiative transitions together, and have calculated radiative transition probabilities for all the three kinds of radiative transitions. Considering a, b and c type transitions together, we have performed Sobolev LVG analysis of each molecule, where the collisional rate coefficients have been obtained using a scaling law. Considering energy levels up to 300 cm-1, we have found 181 weak MASER lines and 112 anomalous absorption transitions of NH2CH2OH, and 21 weak MASER lines and 28 anomalous absorption transitions of CH3NHOH, which may play important role for the identification of respective molecule in the ISM. [ABSTRACT FROM AUTHOR]

Gd2(WO4)3 and Gd2(WO4)3:0.5% Tm3+, 10% Yb3+ nanopowders have been prepared by the Pechini method and solid-state sintering. According to X-ray diffraction results, the materials prepared by the Pechini method are more uniform in phase composition. Optimal synthesis conditions were defined: t = 900°C and τ = 1 h for Gd2(WO4)3 and t = 950°C and τ = 3 h for Gd2(WO4)3:0.5% Tm3+, 10% Yb3+. The surface morphology of the materials has been studied by scanning electron microscopy. The samples prepared by solid-state sintering have been found to be highly agglomerated, and large agglomerates have been shown to persist even after ultrasonic processing. The average size of the doped and undoped nanoparticles prepared by the Pechini method has been determined to be 44.0 and 47.6 nm, respectively. Luminescence spectra of Gd2(WO4)3:0.5% Tm3+, 10% Yb3+ were measured and compared the intensities of the Tm3+1G4 → 3H6, 1G4 → 3F4, 3F1,2→3H6, and 3H4 → 3H6 radiative transitions in the materials prepared by both methods. The data obtained in this study demonstrate that the Pechini process is a preferable and promising method for the synthesis of Gd2(WO4)3 and Gd2(WO4)3:Tm3+,Yb3+ nanopowders. [ABSTRACT FROM AUTHOR]

In this study, Ho3+-doped 0.825K0.5Na0.5NbO3-0.175Sr(Yb0.5Nb0.5)O3 luminescence transparent ceramics were prepared via the traditional solid-state sintering method. The structure and optical properties of the ceramics before and after polarization were studied at 40 kV cm−1 for 0.5 h. With the increase of Ho content, the phase structure of the ceramics changed from a pseudo-cubic phase to the tripartite and the orthorhombic phases, and the light transmittance decreased. The ceramics demonstrated an up-conversion luminescence characteristic under the excitation of a 980 nm laser, and the emission wavelengths were 550 and 670 nm. The best up-conversion luminescence performance was obtained when the Ho content was 0.1%. Moreover, the polarization markedly enhanced the luminescence performance of the 0.825K0.5Na0.5NbO3-0.175Sr(Yb0.5Nb0.5)O3-0.1%Ho ceramics due to the increased possibility of energy-level radiative transition of rare-earth Ho3+ ions and reduction of the Eg value of the ceramic. [ABSTRACT FROM AUTHOR]

Binary neutron star (NS) mergers have been expected to synthesize r-process elements and emit radioactively powered radiation, called kilonovae. Although r-process nucleosynthesis was confirmed by the observations of GW170817/AT2017gfo, no trace of individual elements has been identified except for strontium. In this paper, we perform systematic calculations of line strength for bound–bound transitions and radiative transfer simulations in NS merger ejecta toward element identification in kilonova spectra. We find that Sr ii triplet lines appear in the spectrum of a lanthanide-poor model, which is consistent with the absorption feature observed in GW170817/AT2017gfo. The synthetic spectrum also shows the strong Ca ii triplet lines. This is natural because Ca and Sr are coproduced in the material with relatively high electron fraction and their ions have similar atomic structures with only one s-electron in the outermost shell. The line strength, however, highly depends on the abundance distribution and temperature in the ejecta. For our lanthanide-rich model, the spectra show the features of doubly ionized heavy elements, such as Ce, Tb, and Th. Our results suggest that the line-forming region of GW170817/AT2017gfo was lanthanide-poor. We show that the Sr ii and Ca ii lines can be used as a probe of physical conditions in NS merger ejecta. Absence of the Ca ii line features in GW170817/AT2017gfo implies that the Ca/Sr ratio is <0.002 in mass fraction, which is consistent with nucleosynthesis for electron fraction ≥0.40 and entropy per nucleon (in units of Boltzmann constant) ≥25. [ABSTRACT FROM AUTHOR]

Thermal corrections to the one-photon spontaneous and induced transition probabilities for hydrogen and hydrogen-like ions are evaluated. The found thermal corrections are given by the vertex Feynman graph, where the vertex represents the thermal interaction between the bound electron and the nucleus. All derivations of thermal corrections to bound–bound transitions for an atom exposed to blackbody radiation are made in a fully relativistic approach within the framework of the adiabatic S-matrix formalism. It is found that the vertex-type radiative corrections to the transition rates can be at the level of a few percent to corresponding spontaneous rates for highly excited states in the hydrogen atom. A comprehensive analysis of the vertex-type thermal corrections for hydrogen-like atomic systems is presented. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

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]

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]