Lifetime Values Research Articles

Lifetimes of fine structure levels of the Li atom for 20 < n < 31 by an extended Ritz formula

Lithium and lithium-like elements look like hydrogen atoms if their two electrons and the nucleus are considered as having a core around which a single electron is orbiting. The energy and radii expressions for hydrogen atoms can be used for lithium and lithium-like elements; an important modification is introducing an effective principal quantum number. The effective principal quantum number differs from the principal quantum number of hydrogen by the quantum defect. The quantum defect has respective values for various levels of lithium and lithium-like ions. In this study, we used extended Ritz formulas to calculate quantum defects required to calculate the energies of the ns, np, nd, and nf series up to n < 31. Using these energies, we calculated transition probabilities and then the lifetimes of the lithium levels. The lifetimes were compared with the available published data; an excellent agreement was noticed. The work also extended the available list of lifetimes to higher quantum numbers. Forty lifetimes are newly calculated and presented for the first time. A polynomial formula for each of the ns, np, nd, and nf series lifetimes has been developed that fits well the lifetime values.

Defect analysis of 1-MeV electron irradiated flexible InGaAs solar cells by deep-level transient spectroscopy and photoluminescence

1-MeV electron irradiated InGaAs flexible solar cells were investigated based on solar cell I–V characteristics, external quantum efficiency, photoluminescence, and deep-level transient spectra (DLTS) mesurements. The electrical parameters of the solar cells, including Rs and Rsh, were extracted from the I–V curves. With an increase in irradiation fluence, the electrical and optical characteristics of the solar cells continuously degraded. The Voc, Isc, and Pmax values decreased to 83.16%, 81.96%, and 68.88% of their initial values, respectively, when the irradiation fluence was increased to 2 × 1015 e/cm2. Photoluminescence (PL) emission peak intensity decreased to 0.54% of its original value, and the minority carrier lifetimes derived from fitting PL emission spectra were reduced to 1.25%. DLTS technique was used to analyse the irradiation-induced defect properties. Similar fitting values for the minority carrier lifetimes were obtained from the PL and DLTS measurements.

Lifetime measurement of the Ex = 2485.3 keV level of 25Al populated through 24Mg(p,γ)25Al resonance reaction

Results of our experimental study of the 24Mg(p,γ)25Al resonance reaction at E=plab223 keV are presented. The proton beam energy is varied from 220 to 265 keV. An evaporated Mg target with thick Ta backing is used. We remeasure a mean lifetime of τ=6.04−2.65+3.03 fs for the E=x2485.3 keV level of 25Al, using Doppler shift attenuation (DSA) method. Three most successfully used empirical effective interactions developed for the sd shell by Wildenthal (w), Chung-Wildenthal (cw) and Preedom-Wildenthal (pw), are utilized to calculate energy spectra, spectroscopic factors, beta decay properties, transition probabilities and the lifetime of the resonance state in 25Al within the framework of nuclear shell model. The theoretical results agree reasonably well with the experimental data. However, a detailed study for each set to identify the most preferred interaction for this nucleus is performed. Calculated lifetimes using two of the interactions (w, cw) agree better with the central value of the experimental lifetime of the resonance state measured in the present work.

Enhanced reddish-orange luminescence from Sm3+/Ag co-doped barium zinc borophosphate glasses: Structural and Judd-Ofelt analysis

We report the synthesis and optical response of Sm3+/Ag nanoparticles (NPs) co-doped glasses through melt quenching method. TEM analysis confirmed Ag NP formation, and the diverse functional groups were confirmed through FTIR studies. The Judd-Ofelt (JO) parameters are calculated using JO theory from absorption spectra. The PL spectra were recorded under 402 nm excitation and they show four PL bands in the visible range. The PL spectra are utilized to obtain radiative parameters to claim their utility in visible laser applications. The dominant emission color was obtained by using the CIE color chromaticity diagram. The excited state lifetime values were estimated through decay curve fitting method. All the obtained results are discussed in detail based on Ag NP concentrations.

Key Performance Indicators (KPIs) as Agents for Balancing Industry Needs and Biodiversity Conservation in Manufacturing

The manufacturing industry has a significant negative impact on animals and their habitats. This paper explores the potential of sustainable manufacturing practices to mitigate these impacts. We conducted a comprehensive study of key performance indicators (KPIs) and their influencing factors for sustainability in manufacturing for small and medium-sized enterprises (SMEs) in India. Our findings suggest that KPIs such as social innovation, health and safety, green innovation, waste management, energy conservation, customer lifetime values, and net profit margin are all important factors in sustainability. We also found that these KPIs have high reliability, with Cronbach’s alpha of 0.8 and McDonald’s index of 0.75. Our research provides a framework for assessing sustainability in manufacturing and identifies opportunities for SMEs to reduce their negative impact on animals and their habitats

Pionic final state interactions and the hypertriton lifetime

We analyze the contribution of pionic final state interactions (FSI) in the weak decay of the hypertriton. Focusing on the 3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document}He channel, we find a contribution of the pionic FSI of the order of 18%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$18\\%$$\\end{document}. Assuming a fixed value for the branching ratio R3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R_3$$\\end{document} for the decay width into 3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document}He over the decay width into 3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document}He and pd final states, we find values for the hypertriton lifetime that are consistent with the world average as well as recent measurements by the ALICE Collaboration.

Improving the UV–Vis light-harvesting of Er3+ using Mn4+ as a sensitizer in Li2TiO3 host

A series of Li2TiO3 phosphors, both singly doped with Mn4+ and codoped with Mn4+ and Er3+, were synthesized using a solid-state reaction at high temperatures. In the Li2TiO3:Mn4+/Er3+ system, Mn4+ ions have the ability to absorb UV–Vis photons within the range of 250–600 nm. Subsequently, an energy transfer process occurs between Mn4+ and Er3+ ions, resulting in the emission of near-infrared light originating from Er3+ ions. When excited by light at 365 nm, the Li2TiO3:Mn4+-Er3+ phosphors demonstrated a strong emission in the far-red region, peaking at 682 nm, which corresponds to the 2E→4A2 transition of Mn4+ ions. Additionally, an emission at 1555 nm was observed, associated with the 4I13/2→4I15/2 transition of Er3+ ions. The discussion of the energy transfer from Mn4+ to Er3+ involves the investigation of variations in Er3+ doping and the lifetime values of Mn4+. The absorption of Mn4+ in the UV–Vis range and the subsequent energy transfer to Er3+ ions suggest that these materials could be utilized as spectral converters, enhancing the UV–Vis absorption efficiency of luminescent materials based on Er3+.

Thermal plasma-driven looping for metal scrap processing with hydrogen

In the present research, a novel process was proposed and assessed using an equilibrium thermochemical modelling study to evaluate the performance of a combined disruptive technology of thermal plasma and thermochemical looping to utilise hydrogen for iron reduction processing. The study was aimed at conducting a high-level power performance assessment of the process by integrating a built-in power block with a focus on a novel equilibrium thermal plasma technology for reducing iron scrap particles. The effect of thermal plasma operating parameters such as temperature (1000 °C < T < 1800 °C) and hydrogen-to-iron ratio in the feed stream to the thermal plasma reactor (0 < H2/metal < 20) on the performance of the system was numerically investigated using Aspen coupled with Matlab. Also, the self-sustaining factor was evaluated coupled with a quantitative analysis of the sustainability and lifecycle of the process aiming at better understanding the impact of the proposed system on the environment. Results showed that the system is crucially sensitive to the ratio of H2/metal such that the overall power demand of the reactor can change in a way that the dominant regime of the plasma can change from endothermic (partial reduction of iron) to exothermic (complete reduction, combustion of iron) once the hydrogen to metal ratio exceeds ∼ 2.5. It was also identified that an increase in the temperature of the combustor decreased the power demand for the thermal plasma reactor. Similarly, with increasing the temperature, a ramp-up in the self-sustaining factor was observed reaching 0.8 showing that 80 % of the energy of the auxiliaries can be maintained using the built-in heat recovery and power block. The thermal efficiency of the system was also a strong function of the H2/metal ratio reaching ∼ 0.4 at the H2/metal ratio of ∼ 2.5 reflecting the fact that the proposed process efficiency is within the state-of-the-art power production systems. The sustainability assessments showed that the process offers a high circular economy capability of the process with above-the-average lifetime and Material Circularity Indicator values.

Considerations for determining the performance of ultraviolet light emitting diode fluid disinfection systems.

The International Ultraviolet Association (IUVA) Task Force was formed to develop guidelines regarding testing and reporting on performance of UV LED water disinfection systems. The goal was to provide clarity in a guidance document on measuring system performance across the global UV LED water disinfection system market. A review of current performance measurement protocols for mercury lamp based systems shows that the common elements of UV LED system performance measurement protocols should be as follows: specified standard for the amount of pathogen reduction required, the requirement that the validation testing be conducted by a competent facility, and that the system be continually monitored by UV sensors while in use to verify system performance unless pathogen reduction is not claimed. UV LEDs have selectable peak wavelengths, as opposed to mercury lamps that have fixed emission wavelength values. As a result of this difference, the following changes to protocols used to test mercury lamp systems are recommended. First, the use of disinfection benchmarks other than 254 nm dose, such as direct inactivation values, dose benchmarks referenced to 254 nm, and/or dose benchmarks at the UV LED emission wavelength that give the same inactivation as the original 254 nm UV dose benchmark. Second, the use of 254 nm UV water transmittance values as a placeholder, rather than an assumed correct value, for systems under test with LED wavelengths >250 nm and water transmittance values ≥87%. More research is needed for lower wavelengths and UVTs. Third, the recommendation that germicidal response UV sensors be used in UV LED based systems to ensure that the validated disinfection is delivered. Finally, additional LED-specific considerations were also noted. UV LEDs are also instant-on devices, making them ideal light sources for systems operated intermittently. Performance testing of systems operated intermittently should include a test to insure that pathogens do not migrate past the UV LEDs while the LEDs are off. UV LED devices have recognized protocols for determining the lifetime of the devices, as well as for measuring other device properties. Caution should be exercised in using these lifetime values for devices in UV disinfection systems, since the thermal environment of the devices may be different for protocol testing and disinfection system operation. PRACTITIONER POINTS: Validation of UVC LED fluid disinfection is necessary for point of use, point of entry, and municipal applications. The emission spectrum properties, considerations and measurements for output over lifetime, and unique system design considerations of UVC LEDs as light sources are factors that must be considered when evaluating fluid disinfection performance. The instant-on operation, system geometry, validation benchmarks, system sensing, water transmittance, and fouling must also be considered for UVC LED devices when evaluating fluid disinfection performance.

Simulation and Analysis of Field-dependent Measurements for Different a-Si:H and nc-Si:H Samples

Abstract: A simulation based on the method of weighted residuals is conducted to reproduce the available experimental data of field-dependent steady-state photocarrier grating (SSPG). Different samples of amorphous hydrogenated silicon (a- Si: H) and nanocrystalline hydrogenated silicon (nc- Si: H) thin films prepared by plasma-enhanced chemical vapor deposition (PECVD) technique are employed in the simulation. The reproduced field-dependent data are optimized using 2 indicator. Approximate and correct values of important photoelectronic parameters are extracted from the analysis of results. The analysis reveals values of small-signal response lifetime and electron and hole mobilities comparable to the values obtained from other methods’ applications. The difference between approximate and correct values lies within the experimental error of 5% with one exception regarding a poorly conductive sample. Moreover, the extracted values of both ambipolar diffusion length and charge carrier density are found reasonable and justify the success of the application of the adopted method on the chosen samples. Keywords: Electronic transport phenomena in thin films; Charge carriers: generation, recombination, lifetime, trapping, mean free paths; Photoconduction and photovoltaic effects.

Analysis of tumour oxygenation in model animals on a phosphorescence lifetime based macro-imager

Monitoring of tissue O2 is essential for cancer development and treatment, as hypoxic tumour regions develop resistance to radio- and chemotherapy. We describe a minimally invasive technique for the monitoring of tissue oxygenation in developing grafted tumours, which uses the new phosphorescence lifetime based Tpx3Cam imager. CT26 cells stained with a near-infrared emitting nanoparticulate O2 probe NanO2-IR were injected into mice to produce grafted tumours with characteristic phosphorescence. The tumours were allowed to develop for 3, 7, 10 and 17 days, with O2 imaging experiments performed on live and euthanised animals at different time points. Despite a marked trend towards decreased O2 in dead animals, their tumour areas produced phosphorescence lifetime values between 44 and 47 µs, which corresponded to hypoxic tissue with 5–20 μM O2. After the O2 imaging in animals, confocal Phosphorescence Lifetime Imaging Microscopy was conducted to examine the distribution of NanO2-IR probe in the tumours, which were excised, fixed and sliced for the purpose. The probe remained visible as bright and discrete ‘islands’ embedded in the tumour tissue until day 17 of tumour growth. Overall, this O2 macro-imaging method using NanO2-IR holds promise for long-term studies with grafted tumours in live animal models, providing quantitative 2D mapping of tissue O2.

Improvement of charge carrier lifetime in heat exchange method multicrystalline silicon wafers by extended phosphorous gettering process

External phosphorous diffusion gettering were applied using homogenous and extended schemes on multicrystalline silicon (Mc-Si) wafers obtained from solar grade (SOG) silicon feedstock by the heat exchange method (HEM) growth technique. X-ray fluorescence (XRF) characterization shows the presence of transition metals like Chromium (Cr), manganese (Mn) and iron (Fe) in the analyzed as-cut Mc-Si substrates with a predominance of Mn and Fe elements. Before and after gettering process, we have observed that the Cr atoms concentration drop from 4.1015 at.cm-3 in the as-cut Mc-Si samples to 2.5 1015 at.cm-3 with homogeneous gettering and to 3.1014 at.cm-3 in the wafer undergoes extended gettering. The quasi-steady-state photo conductance (QSSPC) technique is used to characterize the minority charge carrier’s lifetime tn before and after gettering process. It was found that the response of Mc-Si wafers is better (form point of view of lifetime improvement) to the extended process but in some regions it is less effective and the homogenous process give the best amelioration due probably to the spatial distribution of crystalline defects and metallic precipitates densities. With tn initial values before gettering in the range of 2.5-8 usec we have measured lifetime values in the range of 15 to 37 usec with extended process and from 10 to 30 µsec with the homogenous one which ensure cell efficiencies in the range of 15 to 16%.

Understanding the suitable alloying conditions for highly efficient Cu- and Mn-doped Zn1-xCdxS/ZnS core-shell quantum dots

Doping of alloyed colloidal quantum dots (QDs) has garnered significant attention for providing tunable and Stokes-shifted emission. By alloying the host semiconductor nanocrystals (NCs), their band gap can be tuned. With the specific addition of dopant ions, these NCs can emit tunable emissions within the visible spectrum. However, while doped and alloyed quantum dots (QDs) have shown promise for tunable emissions, their emission qualities have not been consistent across the spectrum. Here, we report the synthesis of high-quality Cu- and Mn-doped ZnxCd1-xS (x = 0–1) alloyed QDs by a colloidal non-injection method. In this study, we examined the effect of different dopant ions on the optical properties of similar alloyed nanocrystals. The deposition of a ZnS shell on these doped QDs significantly improves their quantum yield (QY), increasing it from 7.0 % to 50.0 % for Cu-doped QDs and from 30.0 % to 80.0 % for Mn-doped QDs. The Cu-doped QDs exhibit tunable emission from green to red across the visible spectrum by varying the Zn/Cd ratio, whereas the Mn-doped QDs show a fixed orange emission. Interestingly, the Cu-doped alloyed QDs show a contrasting trend in quantum yield (QY) compared to those of Mn-doped QDs when the amount of Cd in ZnCdS alloyed QDs is systematically changed. As the amount of Cd increases in the ZnCdS alloyed QDs, the Cu-doped QDs show both an increase in average lifetime and an increase in QY. In contrast, for the Mn-doped QDs, the decay lifetime values remain fairly constant for different amounts of Cd in the ZnCdS alloyed QDs, but the QY decreases as the amount of Cd increases. The results of this study may facilitate the design of optimal alloying combinations for Cu/Mn-doped QDs in optoelectronic applications.

Reliability testing and assessment of a hydraulic cylinder for precision production

It is significant to promote reliability testing and assessment research of hydraulic cylinder which is the basis to improve reliability of the cylinder and pertinent machine system. In this study, a new comprehensive testing system for the reliability research of hydraulic cylinder has been developed, reliability testing of a hydraulic cylinder for precision production has been conducted using the test bench. With the obtained test data, parameters of the Weibull distribution function of the cylinder are estimated by means of the least square estimation method, thus, reliability distribution function and lifetime values of the cylinder under normal stress level are ultimately obtained. The developed new test bench and performed testing and analysis in this study would provide an excellent platform and reliability assessment approach for industry hydraulic cylinders.

Colour-tunable and warm white light emitting thermally stable Dy3+/Sm3+ co-activated tungstate-tellurite glasses for photonic applications

Transparent single Dy3+, Sm3+, and Dy3+/Sm3+ co-activated tungstate-tellurite (TWKZBi) glass matrices were synthesized via melt-quenching process. The optical features of the prepared glass matrices were examined with the aid of the absorption spectra. Under various excitation wavelengths (366, 388 and 454 nm), Dy3+ doped TWKZBi (TWKZBiDy) glasses revealed a prevailing emission peak ⁓575 nm related to the yellow band (4F9/2 → 6H13/2) transition, while Sm3+ doped TWKZBi (TWKZBiSm) glass matrices reveal strong intense emission peak at ∼600 nm associated with the orange-red band (4G5/2 → 6H7/2) transition. The emission intensity progressively surges with an increment in Sm3+ ion content (up to 1.5 mol%), confirming the ET mechanism between Dy3+ and Sm3+ ions. Application of Dexter's ET formulation with the Reisfeld's approximation revealed that the ET mechanism involves a non-radiative dipole-dipole (d-d) interaction between Dy3+ and Sm3+ ions. The average lifetime (τavg) values for the 4F9/2 state of Dy3+ ions in the TWKZBiDySm glass sample was measured and found that these values decreased with increasing Sm3+ ion content. In addition, the ET efficiencies (ηDy→Sm) of the TWKZBiDySm glass matrices were evaluated using the lifetime curves. The color coordinates (x, y) and the correlated color temperature (CCT) values of the co-activated glass samples were estimated. Based on the chromaticity coordinates and CCT values, it was found that the desired color of the TWKZBiDySm glass samples can be modulated from warm white light to orange-red light via precisely adjusting the concentration of Sm3+ ions and at selected excitation wavelengths. Furthermore, the emission intensity observed at 373 K was 83.83 % compared to the emission intensity at ambient temperature, indicating the excellent thermal stability of the TWKZBiDySm glasses prepared. The above results confirm that the prepared Dy3+/Sm3+ co-activated TWKZBi glass matrix can be a promising candidate for white light and other photonic devices.

New equations to calculate carrier recombination lifetime of silicon epitaxial layer, based on open circuit voltage decay method

Abstract New equations for recombination lifetime calculation based on the open circuit voltage decay (OCVD) method were proposed. The new equations can yield accurate recombination lifetime values of the i-layer of PiN diodes in which a silicon epitaxial layer is employed, by eliminating the effects of carrier diffusion into p+ and n+ layers from the i-layer of PiN diodes, carrier injection into the i-layers from the depletion layer of PiN diodes, and surface recombination on the side wall of PiN diodes. To verify the effectiveness of the new equations, OCVD measurements were performed by employing technology computer-aided design (TCAD) simulation and actual PiN diodes. Although the calculated values implied the effect of epitaxial layer thickness, they were consistent with the results obtained under assumed lifetime conditions for TCAD simulation, the theory of recombination lifetime, and results in other reports.

LCF Lifetime Reliability Prediction of Turbine Blisks Using Marine Predators Algorithm-Based Kriging Method

To achieve the low-cycle fatigue (LCF) lifetime prediction and reliability estimation of turbine blisks, a Marine Predators Algorithm (MPA)-based Kriging (MPA-Kriging) method is developed by introducing the MPA into the Kriging model. To obtain the optimum hyperparameters of the Kriging surrogate model, the developed MPA-Kriging method replaces the gradient descent method with MPA and improves the modeling accuracy of Kriging modeling and simulation precision in reliability analysis. With respect to the MPA-Kriging model, the Kriging model is structured by matching the relation between the LCF lifetime and the relevant parameters to implement the reliability-based LCF lifetime prediction of an aeroengine high-pressure turbine blisk by considering the effect of fluid–thermal–structural interaction. According to the forecast, when the allowable value of LCF lifetime is 2957 cycles, allowing for engineering experience, the turbine degree of reliability is 0.9979. Through the comparison of methods, the proposed MPA-Kriging method is demonstrated to have high precision and efficiency in modeling and simulation for LCF lifetime reliability prediction of turbine blisks, which, in addition to the turbine blisk, provides a promising method for reliability evaluation of complicated structures. The work done in this study aims to expand and refine mechanical reliability theory.

Correlation between deep level traps and reverse recovery of GaAs p–i–n diodes before and after neutron irradiation

Using the deep-level transient spectroscopy and reverse recovery method, the minority carrier lifetime in the base n 0-layers of high-voltage GaAs p +–p 0–i–n 0–n +-diodes grown by the liquid phase epitaxy in argon atmosphere has been estimated before and after irradiation by neutrons with the energy of 1 MeV and the fluence of 1.6 × 1014 cm–2. Correlation between the values of the minority carrier lifetime determined by both methods was found. EL2 defects where shown to govern the dynamic switching characteristics of non-irradiated GaAs diodes, while the switching process in the irradiated diodes is determined by the acceptor-like states of defect bands located above the midgap, which are D– states of a three-charged donor. Having been irradiated with neutrons, the diodes revealed a significant decrease in the time of their reverse recovery upon changing the character of the diode switching from the “hard” mode to the “soft” one.

Improving 2–4 μm mid-infrared fluorescence properties of Ho3+ via Er3+ energy transfer in tellurite glasses

Despite significant advancements in the field of mid-infrared lasers, the fluorescence around the 2–4 μm wavelength range remains a pressing concern. Ho3+/Er3+ co-doped TeO2–ZnO–Nb2O5–PbO (TZNP) glasses were fabricated by conventional melt-quenching technique, and we also characterized their excellent mid-infrared (MIR) fluorescence properties. According to the observed parameter ΔT (144–141 °C) > 120 °C from differential scanning calorimeter (DSC) curves, the manufactured tellurite glass specimens displayed enhanced thermal stability and crystallization resistance. X-ray diffractometer (XRD) images demonstrated the non-crystalline structure of the produced specimens. Ho3+/Er3+ co-doped tellurite glass specimens achieved emission enhancements of 2.0 μm and 4.1 μm through energy absorption of 980 nm LD, which could be assigned to the Ho3+: 5I7 → 5I8 and Ho3+: 5F5 → 5I4 radiation transition processes respectively. Meanwhile, intense 3.1 μm fluorescence was observed, which could be attributed to the transition of Er3+: 4S3/2 → 4F9/2. We investigated the fluorescence properties of the produced glasses in detail, and the processes of energy transferring between Ho3+/Er3+ were discussed on the basis of the quenching and increasing emission intensity at different dopant proportions of Er3+ ions. Additionally, the optimized 1 mol% Ho3+ and 1.5 mol% Er3+ co-doped TZNP glass possessed the strongest emission intensity, and the fluorescence lifetime values of this sample were calculated to be 1.81 ms and 1.38 ms at 2.0 μm and 4.1 μm, respectively. The gain coefficients demonstrated that only small pump energy can achieve the MIR laser gains. These above findings suggest that the prepared samples are potentially competitive and efficient as an innovative glass in the MIR laser design and optical amplifiers applications.

Fluorescence Spectroscopic Studies to Evaluate Binding Interaction between Hoechst 33258 and Bilirubin.

A detailed spectroscopic study (fluorescence, absorption, and lifetime) was conducted to gain insight into the nature of the binding interaction between fluorophore Hoechst33258 (H258) and jaundice marker Bilirubin (Br). The fluorescence emission of the H258 (Ex/Em = 340-502nm) showed a conc. dependent quenching in the presence of Br (1.25 M to 10 M). The Stern-Volmer constant demonstrated an upward curve depicting the occurrence of both static and dynamic quenching with an acquired value of K = 3.1x 10 M and biomolecular quenching rate constant K = 8.6 x 10 M S . The static quenching was evaluated using the sphere of action model and a sphere radius of 0.3nm indicated the presence of a static component in the quenching. The FRET analysis with overlap integral (J) = 1.4x10 M cm nm and Foster Radius(R ) = 26.82 Å with 59% efficiency suggested occurrence of dynamic quenching. Further studies with the time-resolved fluorescence also indicated the presence of dynamic quenching. The lifetime values of H258 reduced from 3.9ns to 0.5ns. Molecular docking studies further support both static and dynamic components in quenching. A non-covalent interaction of H258 with Br in the presence of HSA is predominantly characterized by H-bonding with residues Lys, Asn, Glu, Gln, and Br. The H258 and Br interaction was within the distance of 3.04 Å, which is in coherence with the sphere of action model (0.3nm) and Van-der-Waals along with hydrophobic interactions, which suggested both static and dynamic quenching. Thus, H258 can serve as an efficient fluorophore to monitor binding interactions and can be further exploited as a suitable probe for investigating conformational changes and detection of Br in subsequent studies.