Analysis Of Decay Profiles Research Articles

Multidimensional stimulation response RTP micron fiber thin film

Purpose The purpose of this research is as follows: DPP-BOH-PVA has been synthesized from 1,1′:3′,1″-terphenyl-5'-boronic acid (DPP-OH) and polyvinyl alcohol (PVA). The afterglow lifetime of DPP-BOH-PVA was studied by changing contents of DPP-OH (1, 2 and 4 Wt.%). These films were characterized with Fourier transform infrared, X-ray diffraction as structural analysis and DSC as thermal analysis. Afterglow lifetimes were evaluated as time-resolved emission decay profile analysis. Fiber films of DPP-BOH-PVA-2-E have been prepared by electrospinning method with the diameter of 5 μm and afterglow life time of 2.1 s (@ 535 nm) under ambient conditions. Stimulus responsive properties with afterglow emission for fiber film were investigated. Design/methodology/approach During the synthesis of the polymer, modification was carried out using DPP-OH/PVA with a molar ratio of 1/4, under an alkalinity medium with ammonium hydroxide and with a temperature of 80°C. Findings XRD results indicate that DPP-BOH-PVA film had high crystallinity, which is crucial for preparing organic room temperature phosphorescence (RTP) materials. Research limitations/implications The reaction mixture must be stirred continuously. Temperature should be controlled to prevent the rapid evaporation of ammonium hydroxide. Practical implications This study provides technical information for the synthesis of multidimensional stimulation response RTP micron fiber thin film. The electrospinning technology may also promote the applications of the large areas of RTP films. Social implications This resin will be used for the multidimensional stimulation response RTP fiber thin film. Originality/value The diameter of fiber film of PP-BOH-PVA-2-E by electrospinning method was in the range of 5 μm, and its afterglow lifetime decayed to be 2.1 s.

Decorating wide band gap CH3NH3PbBr3 perovskite with 4AMP for highly efficient and enhanced open circuit voltage perovskite solar cells

Halides based organic-inorganic solar cells have attracted huge attention for efficient energy harvesters owing to their low fabrication cost, large functioning area, long lifetime, and high conversion efficiency. Here we report the fabrication of pristine and aminomethyl piperidinium (4AMP) doped CH3NH3PbBr3 based thin film using spin coating technique to explore its potential for energy harvesting. The structural analysis confirmed the development of the rhombohedral structure of pristine and doped CH3NH3PbBr3. SEM and AFM images revealed that grains for the pure sample are highly compact linked with each other with sharp grain boundaries but their size increased when doped with 4AMP. A direct bandgap of 2.341 eV is noticed for pristine which is slightly decreased to 2.311 eV as a result of doping. The calculation of space charge limited current, PL decay profile analysis, charge transfer resistance, and Mott Schottky analysis provide quite convincing evidence regarding the high conversion efficiency of these films. A sufficiently high value of short circuit current density resulted in high efficiency of pristine MAPbBr3 i.e., 8.46% which increased to 10.21% due to improvement of solar cells parameters such as Voc of 1.46 V when doped with 4AMP. These values of efficiencies make the halide based organic compositions viable for solar cell applications.

Transient carrier recombination dynamics in potential‐induced degradation p‐type single‐crystalline Si photovoltaic modules

AbstractIn this study, we investigated the recombination dynamics of minority carriers through the decay profile analysis of transient diffuse reflectance spectroscopy (TDRS) for fresh and potential‐induced degradation (PID) modules. The PID‐affected region in terms of the degradation degree on the modules was firstly localized using conventional methods such as electroluminescence (EL) and lock‐in thermal images. The photogenerated carrier density and carrier lifetime were different in photovoltaic (PV) modules in fresh and PID modes. It was found that the dominant recombination involved the carrier transition via shallow trap states. The distribution of the trap states, however, was extended from the surface to the bulk of the solar cell due to Na ions–decorated defects. The behaviors of the carrier dynamics near the surface and bulk were very different, as inferred from the two different pump wavelengths of 532 and 1064 nm, respectively.

Photoluminescence and white light generation of Dy2O3 doped Li2O-BaO-Gd2O3- SiO2 for white light LED

Dy3+-doped Li2O-BaO-Gd2O3-SiO2 (LBGS) glasses were prepared by traditional melt quenching techniques and characterized through absorption and emission spectra. Tauc's plot for allowed direct and indirect transition are shown studied and observed in the range of 3.5 (eV) to 2.9 (eV). The variation in the band gap with the addition of Dy2O3 is due to structural changes in the glass matrix. For 0.5 mol% of Dy3+ ions doped LBGS glasses Judd-Ofelt analysis was carried out further these parameters were used to study their radiative properties for the excited luminescent levels of Dy3+ ions. White light generation was evaluated as a function of the Dy3+ ions concentration by measuring yellow-to-blue emission intensity ratios and CIE chromaticity coordinates. The non-exponential decay were observed for glasses doped beyond 0.1 mol% and were well fitted to IH-model for S = 6 (dipole-dipole interaction). The non-exponential behavior and life time quenching have been accredited to the energy transfer through dipole-dipole interaction among the excited and unexcited Dy3+ions. Pulse X-Ray decay time has measured for 0.5 mol% of Dy3+ ions doped LBGS glass. CIE-1931 chromaticity coordinates and decay profile analysis were studied. The correlated color temperature (CCT) for LBGS-0.5Dy is found to be 3621 K at λexc = 350 nm. The quantum efficiency (η) for the title LBGS-0.5Dy glass is found to be 74%. The highest values for radiative transition probability (AR), emission cross section (σ(λP)), experimental and calculated branching ratio (βR) have been observed for 4F9/2 → 6H13/2 at 576 nm.

A Phosphosilicate Compound, NaCa3PSiO8: Structure Solution and Luminescence Properties.

NaCa3PSiO8 was synthesized in a microwave-assisted solid-state reaction. The crystal structure of the synthesized compound was solved using a least-squares method, followed by simulated annealing. The compound was crystallized in the orthorhombic space group Pna21, belonging to Laue class mmm. The structure consisted of two layers of cation planes, each of which contained three cation channels. The cation channels in each of the layers ran antiparallel to that of the adjacent layer. All the major cations together constituted four distinct crystallographic sites. The Rietveld refinement of the powder X-ray diffraction data, followed by the maximum-entropy method analysis, confirmed the obtained structure solutions. The electronic band structure of the compound was analyzed through density function theory calculations. Luminescence properties of the compound, upon activating with Eu2+ ions, were analyzed through photoluminescence measurements and decay profile analysis. The compound was found to exhibit green luminescence centered at ∼502 nm, with a typical broadband emission due to the transition from the crystal-field split 4f65d to 4f7 levels.

Formation and decay analysis ofCd*4898,104isotopes inCa2040-induced reactions

We have analyzed the fusion dynamics of $_{20}^{40}\mathrm{Ca}+_{28}^{58,64}\mathrm{Ni}$ reactions by using the energy dependent Woods-Saxon potential (EDWSP) model and coupled channel model and subsequently the decay patterns of $_{48}^{98,104}\mathrm{Cd}^{*}$ nuclei are governed via the dynamical cluster-decay model (DCM). The influence of intrinsic degrees of freedom of colliding pairs, such as low lying surface vibrations and neutron transfer channels, are entertained within the context of coupled channel calculations. Interestingly, the energy dependence in the Woods-Saxon potential induces barrier modification effects (barrier height, barrier position, barrier curvature) in a somewhat similar way as that for coupled channel approach, hence adequately explains the observed fusion dynamics of $_{20}^{40}\mathrm{Ca}+_{28}^{58,64}\mathrm{Ni}$ reactions. In addition, the decay analysis of compound nuclei formed in the fusion of $_{20}^{40}\mathrm{Ca}+_{28}^{58,64}\mathrm{Ni}$ reactions is investigated by using DCM. The calculations are done for quadrupole $({\ensuremath{\beta}}_{2})$ deformed fragments having optimum orientations for hot configurations. The experimental data for evaporation residues lying within the wide range of center of mass energy $({E}_{\mathrm{c}.\mathrm{m}.})$ of $64--88$ MeV is nicely addressed using the collective clusterization approach of the DCM. The comparative analysis of decay profiles of $_{48}^{98,104}\mathrm{Cd}^{*}$ is worked out by introducing angular momentum and temperature effects in the fragmentation potential and preformation factor.

Enhanced Luminescence of Ca14 Mg2 Si8 O28+δ N4−δ :Eu2+ Phosphors by Codoping Ce3+ , Mn2+ for White LEDs and Their Energy-Transfer Mechanism

The Eu2+, M-codoped(M = Ce3+, Mn2+) phosphor powders were prepared by a solid-state reaction. The addition of Ce3+ in the Eu2+ sites in partially nitridated bredigite-structure phosphor(CMSN) remarkably enhances the luminescent intensity by ~180% through sensitized luminescence. Dual band emission was observed for Eu, Mn-codoped CMSN through energy transfer from Eu2+ to Mn2+. Ce3+–Eu2+ and Eu2+–Mn2+ energy-transfer mechanism was investigated through decay profile analysis using Inokuti–Hirayama model and energy-transfer parameters are determined. Interaction mechanism was identified as dipole–dipole interaction. In addition, phosphor in glass plates was prepared using the phosphor and its feasibility in white LED application was studied and is presented.

Color-tunable binary solid-solution phosphor, (Sr3SiO5)1−x(Sr3AlO4F)x, for white LEDs: Energy transfer mechanism between Ce3+ and Tb3+

The possibility of using a solid solution as a light convertor in white LEDs was studied. A solid solution of Sr3AlO4F and Sr3SiO5 was prepared by solid-state reaction and was activated with Ce3+. Phosphor exhibits an asymmetric yellow–orange emission band which is broadened and red-shifted when coactivated with Tb3+. Decay profile analysis using the Inokuti–Hirayama model revealed that the mechanism involved was electric dipole–quadrupole interaction. The critical distance was calculated from concentration quenching data, multipolar interaction, and exchange interaction. The thermal stability of photoluminescence was investigated by assuming an Arrhenius temperature dependence, and the activation energy for thermal quenching was calculated. When analyzed in combination with an InGaN LED, the phosphor exhibited high color-rendering index and excellent correlated color temperature. These results demonstrate that this solid solution phosphor with its superior properties is highly suitable for use in white LEDs.

Fabrication and spectroscopic characterization of Ce3+ doped Sr2Y8(SiO4)6O2 translucent ceramics

Ce3+ doped Sr2Y8(SiO4)6O2 translucent ceramics were successfully fabricated by spark plasma sintering and their photoluminescent properties were studied in correlation with the crystal structure. There are two crystallographic sites AI and AII for Ce3+ in the Sr2Y8(SiO4)6O2 host and according to the analysis of the photoluminescence spectra, the energy levels of Ce3+ at AI and AII sites were demonstrated by the configurational coordinate model. The spectroscopic characteristics also indicated that the energy transfer from Ce3+ at AI to those at AII occurred. This energy transfer became more pronounced with higher Ce3+ doping concentration, which is confirmed by the analysis of decay profiles.

Determination of uranium(VI) sorbed species in calcium silicate hydrate phases: A laser-induced luminescence spectroscopy and batch sorption study

Batch sorption experiments and time-resolved luminescence spectroscopy investigations were carried out to study the U(VI) speciation in calcium silicate hydrates for varying chemical conditions representing both fresh and altered cementitious environments. U(VI) uptake was found to be fast and sorption distribution ratios (Rd values) were very high indicating strong uptake by the CSH phases. In addition a strong dependence of pH and solid composition (Ca:Si mol ratio) was observed. U(VI) luminescence spectroscopy investigations showed that the U(VI) solid speciation continuously changed over a period up to 6months in contrast to the fast sorption kinetics observed in the batch sorption studies. Decay profile analysis combined with factor analysis of series of spectra of U(VI) – CSH suspensions, recorded with increasing delay times, revealed the presence of four luminescent U(VI) species in CSH suspensions, in agreement with the batch sorption data. Along with the aqueous UO2(OH)42- species and a Ca–uranate precipitate, two different sorbed species were identified which are either bound to silanol groups on the surface or incorporated in the interlayer of the CSH structure.

Pulmonary Capillary Pressure Measurement from Pulmonary Artery Occlusion Pressure Decay Profile Analysis in Sheep

Pulmonary capillary pressure (Ppc), the major factor responsible for pulmonary edema, cannot be directly measured in intact subjects but may be estimated by analysis of the pressure decay profile after pulmonary artery catheter balloon inflation. We compared three different methods of pulmonary artery occlusion pressure (Ppao) decay profile analysis to estimates of Ppc derived from lymph flow measurements in halothane-anesthesized sheep. The relationship between Ppc and lymph flow was first determined by increasing Ppc by left atrial balloon inflation, and was then used to determine Ppc during pulmonary hypertension produced by infusion of a thromboxane analog. All three methods of Ppao decay profile analysis demonstrated a correlation with Ppc estimated from lymph flow. However, the method using a single exponential analysis significantly overestimated Ppc, and none of the methods reliably estimated changes in the longitudinal distribution of pulmonary vascular resistance during pulmonary hypertension. These results suggest that Ppao decay profile analysis as currently performed has limited application.

Pulmonary Capillary Pressure Measurement from Pulmonary Artery Occlusion Pressure Decay Profile Analysis in Sheep

Pulmonary Capillary Pressure Measurement from Pulmonary Artery Occlusion Pressure Decay Profile Analysis in Sheep

Direct non‐radiative energy transfer studies of interdiffusion latex films: Strategies for data analysis

AbstractWe are interested in studying polymer diffusion across an interface by direct non‐radiative energy transfer. In this paper we examine different approaches and techniques to analyze fluorescence decay data in such systems. One type of technique is used to calculate a parameter fm characterizing the extent of mixing. A second technique allows the concentration profile of the acceptor dyes at the interface to be evaluated. The third technique introduces the diffusion model into the decay profile analysis and yields the diffusion coefficient of the polymers. We found that when characterizing the extent of interdiffusion using the fraction parameter fm, ignorance of the detailed concentration gradient does not introduce significant error. The evaluation of diffusion coefficients is a complicated task due to the broad distribution of polymer molecules in latex films.

Time-resolved study of tryptophan fluorescence in vesicle reconstituted cytochrome oxidase: Effect of redox transition

Time-resolved study of fluorescence decay of the tryptophan residue in bovine cytochrome c oxidase in phospholipid vesicles is reported for the first time. The effect of the redox state of the protein on its conformation has been investigated using time-resolved decay of tryptophan fluorescence in the oxidised and reduced protein. The fluorescence decay was best fitted using a discrete three exponential model. Amplitude distribution of lifetimes also showed three distinct regions in the analysis of decay profiles by the maximum entropy method (MEM). Results of the time resolved studies showed that the amplitudes as well as the lifetimes of the trytophan fluorescence remain the same for the oxidised and the reduced states ofcytoehrome c oxidase, indicating that the environment around tryptophan residues remains more or less unaltered on reduction of the protein. The results suggest that there is no global conformational change in the protein on electron transfer and support the possibility of the existence of local fluctuations in the protein during the redox cycle. p]Cytochrome c oxidase; Tryptophan fluorescence; Conformational change

The UV absorption spectrum of the ethylperoxy radical and its self-reaction kinetics between 218 and 333 K

The UV absorption spectrum of the C 2H 5O 2 radical between 215 and 295 nm, and the kinetics of its self-reaction in the temperature range 218–333 K were measured using the molecular modulation technique in conjunction with both single wavelength and diode array UV spectroscopy. The UV spectrum of C 2H 5O 2 is a broad absorption with a σ max of 4.36 × 10 −18 cm 2 molecule −1 at 240 nm. Analysis of decay profiles of C 2H 5C 2 at 250 nm enabled an overall removal rate constant k obs for C 2H 5O 2 of (1.1 ± 0.1) × 10 −13 cm 3 molecule −1 s −1 at 298 K to be determined. Between 250 and 330 K, k obs may be represented by k obs(250–330 K) = (1.85 × 0.2) × 10 −13 exp{−[(147 ± 30)/ T]} cm 3 molecule −1 s −1. A further expression is presented for lower temperatures where curvature in the Arrhenius plot is observed. Comparisons with previous measurements of σ(C 2H 5O 2) and the temperature dependence of k obs are presented.

Phosphorimeters for analysis of decay profiles and real time monitoring of exponential decay and oxygen concentrations

A phosphorimeter which can be assembled at low cost from mainly commercially available components and which has better time resolution, data acquisition rate, sensitivity, and flexibility than commercially available instruments is described. As a phosphorescence analyzer the instrument can measure phosphorescence lifetimes ranging from ∼ 30 μs to seconds from samples with variable intensity, excitation, and emission spectra and which may follow complex decay behavior. Configured as a phosphorescence monitor it is designed for fast, repetitive calculation of phosphoresence lifetime, assuming single-exponential decay, and can be used to calculate oxygen concentration in biological samples in real time.