Emission Intensity Ratio Research Articles

Achiral Dichroic Dyes‐mediated Circularly Polarized Emission Regulated by Orientational Order Parameter through Cholesteric Liquid Crystals

AbstractIt is noteworthy that cholesteric liquid crystal (CLC) platforms have been witnessed in high‐performance circularly polarized luminescence (CPL) behaviors through the highly organized chiral co‐assembled arrangement of achiral dyes. However, most CPL‐active design strategies are closely relative to the helix co‐assembly structure of CLC rather than achiral dyes. Herein, we developed an intriguing regulation strategy for CPL‐active CLC materials. They were regulated using the orientational order parameter (SF) of achiral dichroic dyes as an incisive probe for the order arrangement degree of achiral dyes in CLC media. The I‐shaped phenothiazine derivative PHECN dye (SF=0.30) emitted a strong CPL signal (|glum|=0.47). In contrast, the T‐shaped derivative (PHEBen) dye (SF=0.09) showed a weak circular polarization level (|glum|=0.07) at similar CLC textures. Most interestingly, this kind of dichroic PHECN dye with a higher SF could greatly improve the contrast ratio of CPL (Δglum=0.47) and emission intensity (ΔFL=46.0 %) at direct‐current electric field compared with the T‐shaped PHEBen (Δglum=0.07 and ΔFL=1.0 %) in CLC. This work demonstrates that an induced CPL emission can be mediated using achiral dichroic dye, which will open a new avenue for developing excellent CPL‐active display materials.

Aliphatics and Aromatics in the Universe: The Pre-JWST Era

The so-called “unidentified infrared emission” (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm ubiquitously seen in a wide variety of astrophysical regions are generally attributed to polycyclic aromatic hydrocarbon (PAH) molecules. Astronomical PAHs often have an aliphatic component (e.g., aliphatic sidegroups like methyl –CH3 may be attached as functional groups to PAHs) as revealed by the detection in many UIE sources of the aliphatic C–H stretching feature at 3.4 μm. With its unprecedented sensitivity and spatial resolution, and high spectral resolution, the James Webb Space Telescope (JWST) holds great promise for revolutionizing the studies of aliphatics and aromatics in the Universe. To facilitate analyzing JWST observations, we present a theoretical framework for determining the aliphatic fractions (η ali) of PAHs (the fractions of C atoms in aliphatic units) from the emission intensity ratios of the 3.4 μm aliphatic C–H feature to the 3.3 μm aromatic C–H feature. To demonstrate the effectiveness of this framework, we compile the 3.3 and 3.4 μm UIE data obtained in the pre-JWST era for an as-complete-as-possible sample, and then apply the framework to these pre-JWST data. We derive a median aliphatic fraction of 〈η ali〉 ≈ 5.4%, and find that the aliphatic fractions are the highest in protoplanetary nebulae illuminated by cool stars lacking ultraviolet radiation. Nevertheless, the “hardness” of stellar photons is not the only factor affecting the PAH aliphaticity, and other factors such as the starlight intensity may also play an important role.

One-pot synthesis of lanthanide-doped silica film as a ratiometric fluorescent probe for selective amine vapours detection

In this work, the development of a novel paper-supported ratiometric fluorescent sensing platform for amines detection and discrimination based on co-doped Tb3+ and Eu3+ silica film is reported. The sensor film was obtained by the sol-gel process, in a one-pot straightforward synthesis approach. After exposure to different amines, the resulting intensity ratio between Tb3+ and Eu3+ emission bands presents characteristic values that can be ascribed to the different amines. The higher emission intensity ratios were found for amines with the higher pKa values, as in the case of biogenic amines. The sensor can be stored for more than 120 days, keeping the capacity to detect and distinguish different amines. The prepared fluorescent probe was tested as a food freshness indicator in beef and tuna samples, where notable changes were observed during the food degradation. This proof-of-concept shows the capability of the developed sensor platform to be applied in the detection of multiple amines, and in daily and quality control operations by “naked-eye” inspection.

Photoluminescence Color Prediction for Eu3+‐Doped Perovskite Red Phosphors Using Machine Learning

Currently, data‐driven approaches for exploring novel materials are garnering significant attention with the expectation of accelerating material development cycles and understanding materials from various aspects. This short article presents a supervised prediction model for the emission intensity ratio of 5D0–7F2 and 5D0–7F1 transition of Eu3+ ions, called an “asymmetry ratio”, which determines the color purity of the red region of Eu3+ photoluminescence in perovskite phosphors. The model is developed using a dataset of 296 samples and 203 descriptors for Eu3+‐doped perovskite. The accuracy of the prediction model trained by the dataset is statistically evaluated, which validates its sufficiently high prediction performance. Furthermore, the prediction model's performance is properly assessed by synthesizing a Eu3+‐doped NaLaInNbO6 compound, which is unknown as a red phosphor, and by comparing the experimental asymmetry ratio for this compound with that predicted by the predictor, which exhibits satisfactory agreement.

Interplay of Consecutive Energy Transfer and Negative Thermal Expansion Property for Achieving Superior Anti‐Thermal Quenching Luminescence

AbstractLuminescence thermal quenching (TQ) is one of the most critical problems to be solved for further improvement of phosphors’ applications in lighting and many other fields. Herein, a novel strategy is demonstrated to achieve outstanding anti‐TQ performance with a substantial enhancement of Eu3+ red emission at 613 nm from Sc2MO3O12:Tb3+,Eu3+ phosphor. Its anti‐TQ performance is endowed by dual energy transfer (ET) pathways and intensified by the negative thermal expansion (NTE) property of the Sc2MO3O12 host. Remarkably, the photoluminescence (PL) emission intensity of Eu3+ from Sc2MO3O12:20%Eu3+,2%Tb3+ phosphor at 648 K reaches 507.3% of the initial intensity taken at 298 K. The lifetime of Eu3+ emission at 613 nm elongates with increasing measurement temperature. The experimental data and density functional theory (DFT) calculations reveal that the host structure shrinkage via NTE leads to the thermally boosted Eu3+ red emission by intensifying the consecutive ET and confinement of the absorption light. The potential of this phosphor as a dual‐mode high temperature thermometer based on both emission lifetime and intensity ratio read‐out modes is realized. This work provides inspiration to combine multiple strategies to achieve broad and dramatic anti‐TQ phosphors with enhanced performance for various optical applications.

Ratiometric fluorescent sensing of melatonin based on inner filter effect and smartphone established detection

Melatonin (MLT) is a crucial neurohormone having inhibitory effects over various types of cancer. In this work, 3,6-Diaminocarbazole (DAC), a fluorescent probe is utilized to detect MLT in a highly sensitive, selective and facile way. The unique feature of present work is that MLT is sensed by ratiometric fluorescent technique based on the inner filter effect (IFE) using DAC at an emission wavelength of 310 nm. As a result, a noticeable change in color from red to cyan is observed and the quantitative analysis of fluorescence signals at these wavelengths are used to detect MLT observing a linear relationship between the ratio of emission intensities and the concentration of MLT over a linear range of 0 to 78 μM. DAC can accurately measure the detailed quantity of MLT with a limit of detection of 30 nM and has proved to be an efficient sensing probe due to its excellent molar absorptivity and high photoluminescence quantum yield (PLQY). Sensing characterization was carried out UV–Vis, steady-state, and time- resolved fluorescence spectroscopic techniques. The smartphone app “RGB colour detector” value has been successfully linked with the considerable detectable color changes of DAC on addition of MLT. HOMO-LUMO have been calculated using DFT with B3LYP/6-31G(d,p) level and band gaps of 3.77 eV and 4.91 eV were found for DAC and MLT, respectively. Electrons are not allowed energetically to transfer from MLT to DAC, as is evident from their band gaps. Therefore, IFE can be considered the foremost method in fluorescence quenching of present investigation. The developed sensor was verified by spiking of MLT in human serum.

Enhanced UV Light‐Emission of Zinc‐Phosphate‐Hydrate Hydrothermally‐Grown on Cu Metal Substrates for Opto‐Electronic Applications

AbstractIn the present study, polycrystalline films of layered zinc phosphate hydrate are produced by a facile, low‐temperature single‐step hydrothermal fabrication method on top of Cu metal substrates. Despite containing structural water, the as‐grown films remain crystalline, chemically stable, and electrically conductive. The photoluminescence spectrum obtained at room‐temperature reveals the presence of a spectrally narrow, high‐intensity ultraviolet band that consists of two Gaussian peaks at ≈377 and 383 nm and a UV‐to‐visible peak emission intensity ratio of ≈5.3. The electrical charge‐transport properties remain Ohmic for electric fields of up to ≈2 kV m−1 and temperature (T) range of ≈223–368 K. The electrical conductivity is further found to vary exponentially with the inverse temperature, and the thermal activation energy, Ea is 285 ± 8 meV. A moderate UV‐vis photoconduction effect is registered and assigned to light‐assisted electronic transitions that involve near‐band edge defect states. This study can potentially open a door to the engineering and deployment of water‐based compounds with advanced, semiconducting‐like attributes in short‐wavelength opto‐electronic devices.

Effects of water molecules on luminescence in europium and terbium coordination polymers with p-fluorobenzoic acid as ligand

Our previous experimental observations show that the crystal structure of lanthanide luminescent complexes synthesized in aqueous solution usually contains a large number of coordination water molecules or free water molecules. In order to probe the influence of water molecules on luminescent processes of lanthanide complexes, the photoluminescence properties of Ln-FBA (Ln = Eu and Tb, FBA = p-fluorobenzoic acid) coordination polymers at different ambient temperatures, in different solvents and aqueous DMSO solutions with different volume concentrations were systematically investigated. The experiment results show that the presence of water molecules can promote the energy transfer from FBA ligand to Ln3+, at the same time, can cause luminescent non-radiation quenching of lanthanide ions. In addition, the variation of emission intensity ratio of 615 nm/591 nm peaks of Eu3+ with increasing the volume concentration of H2O can be potentially used for the quantitatively detection of water traces in organic solvents. In order to suppress the non-radiation quenching caused by the water molecules, Ln-FBA (Ln = Eu and Tb) coordination polymers were embedded into the PVP matrix to prepare Ln-FBA@PVP hybrid materials. The photoluminescence investigation indicates that PVP can not only block the quenching effect of water molecules on luminescence, but also effectively sensitize Eu3+ and Tb3+ luminescence. These experimental conclusions are useful for probing the influence of water molecules on luminescent processes of lanthanide complexes, quantitatively detecting water traces in organic solvents and enhancing the photoluminescence intensity in lanthanide complexes.

Highly sensitive dual-mode thermometry over a wide temperature range based on bandgap engineering in LiNb1-xTaxO3:Tb3+

Having proved that highly sensitive dual-mode optical thermometry could be implemented based on fluorescence intensity ratio (FIR) of the same green emission driven by varying excitations and fluorescence lifetime (FL) of Tb3+, the feasibility to manage thermometric performance over a wide temperature range via bandgap engineering is validated in LiNb1-xTaxO3:Tb3+. The vital thermally activated relaxation processes via an intervalence charge transfer state are altered by formulating crystal structure via partial replacement of Nb5+ with Ta5+, allowing adjustment of the sensitive temperature range which can be measured with the highest accuracy. Specifically, maximum relative sensitivities SR up to 1.43 and 2.36 %K−1 are respectively attained in FIR and FL modes of LiNb1·0Ta0·0O3:Tb3+. The upper limit of the sensitive temperature range is proved to be greatly extended from 260 to 440 K for LiNb0·2Ta0·8O3:Tb3+. This work may provide a perspective approach to design self-calibrated thermometers targeted at different temperature ranges for varying applications.

Color Tuning and Optical Temperature Sensing Properties of Upconversion Emission in Yb3+/Er3+/Tm3+Doped Boro-Zinctellurite Glasses

Zinc borotellurite (B2O3/BaO/ZnO/TeO2) glasses co-doped with Tm3+/Yb3+, Er3+/Yb3+ and tri-doped Tm3+/Er3+/Yb3+ were prepared using the traditional melt quenching method. Optical absorption spectra were measured in the wavelength range of 350 nm-1100 nm at room temperature. The optical bandgap (Eg) and Urbach energy were calculated from Tauc’s plot. Blue and green emissions that can be seen by the naked eye were generated under 975 nm laser light excitation in doped Tm3+/Yb3+ and Er3+/Yb3+ doped glasses. Shifts in both blue and green color coordinates were seen as the excitation power density increased from 0.5 to 15.1 W cm−2. A white light generation was generated in glass doped with Tm3+/Er3+/Yb3+ ions, although a noticeable shift was not observed in both blue and green color coordinates for the same excitation power density range. Temperature sensing properties were investigated using the fluorescence intensity ratio of upconversion green emissions from the two thermally coupled 2H11/2 and 4S3/2 levels of Er3+ ions between 304 K and 443 K. The maximum sensitivity of the glasses doped with Er3+ and Er3+/Yb3+ were found to be 7.2 × 10−3 K−1 and 1.2 × 10−2 K−1 at 429 K, respectively.

A Reversible Dual-Channel Near-Infrared Flavonoid Probe for in Vivo Tracking Glutathione Dynamics in Living Mice.

Glutathione (GSH) plays a critical role in various biological processes maintaining oxidative homeostasis. However, current reversible probe fluorescence emission is usually in the visible region, making it difficult to monitor glutathione levels in deep tissues and in vivo. Here, we developed a reversible near-infrared fluorescence probe, Flav-N, for real-time tracking of GSH in cells and tissues, which undergoes fast and reversible Michael addition reactions with biothiols. This Flav-N probe showed a rapid and reversible response with GSH at a time of less than 5 s (k = 1286 M-1S-1, t 1/2 = 729 ms). Notably, the dynamic changes in the ratio of Flav-N emission intensity at 505 and 728 nm were able to provide real-time feedback on the fluctuation of GSH concentration. We demonstrated that Flav-N enables the performance of fast and reversible imaging of intracellular GSH changes. Importantly, in light of the near-infrared emission and rapid response ability, Flav-N was successfully applied to track GSH dynamics in living mice. This reversible near-infrared NIR probe realizes advances in deep insight into the function of endogenous GSH.

Fluorescence on and off sensing platform based on europium nanosheets for the detection of DPA and Cu2+ ions.

With the development of society, the modern environment has put forward higher requirements for analysis and detection. This work proposes a new strategy for the construction of fluorescent sensors based on rare-earth nanosheets. Organic/inorganic composites were obtained by the intercalation of 4,4'-stilbene dicarboxylic acid (SDC) into layered europium hydroxide, and then the composites were exfoliated to form nanosheets. Taking advantage of the fluorescence emission characteristics of SDC and Eu3+, a ratiometric fluorescent nanoprobe was constructed, which realized the detection of dipicolinic acid (DPA) and Cu2+ in the same system. With the addition of DPA, the blue emission of SDC gradually decreased and the red emission of Eu3+ gradually increased, when Cu2+ was added, the emission of SDC and Eu3+ were gradually weakened. The experimental results showed that the ratio of fluorescence emission intensity (I619/I394) of the probe had a positive linear relationship with the concentration of DPA, and a negative linear relationship with the concentration of Cu2+, thus realizing the high sensitivity detection of DPA and a wide detection range of Cu2+. In addition, this sensor also exhibits potential visual detection possibilities. This is a multifunctional fluorescent probe that provides a novel and efficient method for the detection of DPA and Cu2+, which broadens the application field of rare-earth nanosheets.

Evolution Between Exciton and Exciplex Emission in Planar Heterojunction OLEDs with Different Hole-Injection Characteristics

Planar heterojunction-based organic light-emitting diodes (PHJ OLEDs) usually have simultaneous exciton and exciplex emissions and understanding their evolution processes is crucial for designing high-performance white OLEDs, but relevant evolution mechanisms are still unclear. Here, unreported competitions between exciton and exciplex emissions and an undiscovered energy-transfer channel from triplet exciton to triplet exciplex states in PHJ OLEDs with different hole-injection abilities are investigated by separately measuring their current-dependent electroluminescence (EL) spectra and magneto-EL (MEL) traces at different temperatures. Interestingly, the ratio of emission intensity between exciton and exciplex states ($R={I}_{\mathrm{exciton}}/{I}_{\mathrm{exciplex}}$) from the device with a good hole-injection ability rises with increasing bias current at each temperature, whereas that from the device with a poor hole-injection ability hardly changes. In addition, R from the devices with good and poor hole-injection abilities show nonmonotonic variation and monotonic reduction with decreasing operational temperature at each bias current, respectively. These various current- and temperature-dependent competitions between exciton and exciplex emissions are attributed to distinct current- and temperature-dependent electron-tunneling effects occurring at organic heterojunction interfaces of devices with different hole-injection abilities. More intriguingly, using MEL as a fingerprint detection tool, we find there is a Dexter energy-transfer (DET) channel from the triplet exciton to triplet exciplex (${T}_{1}\ensuremath{\rightarrow}{\mathrm{EX}}_{3}$) state and the DET can enhance the reverse intersystem crossing (RISC) process from triplet to singlet exciplexes (${\mathrm{EX}}_{3}\ensuremath{\rightarrow}{\mathrm{EX}}_{1}$), which cannot be found using the conventional probing tool, EL spectra. Because the numbers of ${T}_{1}$ excitons in these devices have different current and temperature dependencies, various current- and temperature-dependent DET and RISC processes happen, which cause abundant MEL behaviors. Obviously, this work deepens the physical understanding of the competition and DET processes between exciton and exciplex states in PHJ OLEDs.

In situ diagnostics of the Si etching structures profile in ICP SF6/C4F8 plasma: Macrostructures

In this work, we studied the influence of technological parameters of plasma chemical etching of silicon on silicon etching rate, photoresist etching rate, etching selectivity of silicon in relation to a photoresist, and sidewall angle of etched structures. It was found that the silicon etching rate increases with raising percentage of SF6 in the gas mixture (25%–50%), pressure (1–2.5 Pa), high-frequency (HF) power (1000–2000 W), and bias voltage module (15–75 V) and decreases with a raising total flow rate of the gas mixture (5–35 SCCM) due to the increasing passivation efficiency of the sample surface. The etching selectivity increases with a raising percentage of SF6 and pressure and decreases with the raising total gas flow rate, HF power, and bias voltage module due to different influences of technological parameters on the photoresist etching rate. In addition, based on the obtained results, a common regularity between the sidewall angle and the optical emission spectra was revealed. The method of in situ diagnostics was proposed, namely, controlling the sidewall angle by a ratio of emission intensities of a carbon line (517.1 nm) to a fluorine line (685.8 and 703.9 nm) designated as parameter X. It was found that the sidewall angle of etched structures takes certain values depending on the value of the X parameter. The ranges of X values at which the sidewall angle is acute, right, and obtuse were estimated. So, at values of X from ≈0.15 to ≈0.35, an acute angle (from 81° ± 0.5° to 89° ± 0.5°) is obtained; at X from ≈0.35 to ≈0.42, a right angle is obtained (90° ± 0.5°); and at X from ≈0.42 to ≈0.75, the values of the sidewall angle are in the range from 91° ± 0.5° to 94° ± 0.5°, no matter which technological parameters were set. Experiments were conducted for etching windows with linear dimensions from 0.5 × 20 to 2 × 20 mm.

In situ determination of sputtered Ni–Cu film composition from emission intensities

In situ elemental analysis of films comprising multielements deposited by sputtering is necessary to improve the reliability of the films because small changes in the film composition affect the properties of the films. Recently, we developed a method to determine the composition of Cu–Zn films by measuring the intensities of emission lines of Cu and Zn during sputter deposition. However, this method was only applicable to a constant chamber pressure, and only a narrow composition range (65.9–80.6 at. % of Cu in the target) was investigated. In this study, the applicability of this method was investigated for a wide range of film compositions, and the combination of emission lines that can be used to determine the film composition regardless of the chamber pressure was determined. This was achieved using Ni–Cu alloy targets, whose Cu composition ranged from 29.4 to 85.3 at. %, by evaluating the linearity (R2 value) between the emission intensity ratio of Ni/Cu lines and the atomic ratio of Ni/Cu in the films. An R2 value of 0.9870 was obtained for the combination of Ni 338.1 nm and Cu I 296.1 nm lines at chamber pressures from 1 to 5 Pa. This result indicates that the composition of Ni–Cu films can be determined from the intensities of the emission lines of Ni and Cu during sputter deposition regardless of the chamber pressure.

A naphthalimide functionalized fluoran with AIE effect for ratiometric sensing Hg2+ and cell imaging application

The pollution caused by mercury ions (Hg2+) poses a potential threat to public health. Therefore, monitoring Hg2+ concentration in the environment is necessary and significant. In this work, a naphthalimide functionalized fluoran dye NAF has been prepared, which shows a new red-shift in emission at 550 nm with the maximum intensity in a mixture of water-CH3CN (v/v = 7/3) due to aggregating induced emission (AIE) effect. Meanwhile, NAF can be employed as a Hg2+ ions sensor, which displays a selective and sensitive response to Hg2+ ions by the reduced fluorescence of naphthalimide fluorophore and increased fluorescence of fluoran group, respectively, showing ratiometric fluorescence signal changes with more than 65-fold emission intensity ratio increase and naked eyes visible color change. In addition, the response time is fast (within 1 min) and the sensing can be conducted in a wide pH range (4.0–9.0). Moreover, the detection limit has been evaluated to be 5.5 nM. The sensing mechanism may be attributed to the formation of a π-extended conjugated system due to the Hg2+ ions-induced conversion of spironolactone to the ring-opened form, partially accompanied by the fluorescence resonance energy transfer (FRET) process. Significantly, NAF exhibits suitable cytotoxicity to living HeLa cells, which allows it to be utilized for ratiometric imaging of Hg2+ ions assisted by confocal fluorescence imaging.

Synthesis, structural and temperature-sensing properties of nanosized Y2Ba3B4O12: Nd3+/Yb3+ phosphors

This work involved the synthesis and characterization of the Y2Ba3B4O12 phase that has undergone various heat treatment periods and temperatures. This study concentrated on optical nanothermometry applications, with an emphasis on the near-infrared (NIR) spectrum and the temperature range of 25–55 °C to assess potential biological applications. The polymeric precursor method was used for the synthesis of Y2Ba3B4O12 nanoparticles co-doped with Nd3+ and Yb3+ with (0; 0.2; 0.5; 1.0 and 2.0) mol% treated at 1000 °C for 5 min, after the structural and spectroscopic thermal characterizations were performed. In order to confirm the heat treatment temperature (1000 °C for 5 min) for the production of crystalline phases, measurements employing thermal analysis (thermogravimetry and differential exploratory calorimetry) were used. The creation of the materials' pure phase was confirmed by the structural characterization performed using Raman spectroscopy and X-ray diffraction. Through Transmission Electron Microscopy it was possible to measure the size (∼110 nm) and different shapes of the particles and by electron diffraction the crystallite monocrystalline character was observed. We were able to analyze the doping ions' absorption bands using diffuse reflectance spectroscopy, to evaluate the high reflectance region of the matrix (areas where the pure matrix does not absorb), and to determinate the optical bandgap using the Kubelka-Munk equation. Additionally, it was examined how the fluorescence intensity ratios of Stark components changed as a function of temperature. In relation to the intensity ratio of the powder's emissions at 897 nm and 978 nm, the maximum sensor thermal sensitivity of 0.31%.°C−1 was determined.

N-ion-implanted ZnO microtubes for highly-efficient UV detection

Here we report a N-ion-implanted ZnO microtube fabricated by optical vapor supersaturated precipitation (OVSP) and ion implantation techniques. The N ions with concentration of ∼2.4 × 1023 cm−3 were mainly located below 100 nm of the surface in the acceptor-rich ZnO (A-ZnO) microtubes. Due to the presence of N in ZnO lattice as NO defects, an ∼15-fold enhancement of near-band edge (NBE)/deep-level emission (DLE) intensity ratio was achieved. The yellow luminescence and the anomalous negative thermal quenching (NTQ) effect further confirmed the NO defect level of 1.3 eV above the valence band maximum in A-ZnO:N microtubes. The implantation of N ions can expand the depletion layer between A-ZnO:N detector and atmospheric species, by which fast photoresponse down to 0.1 s was realized by a metal-semiconductor-metal (MSM) UV detector. Compared with the A-ZnO UV detector, the photoresponsivity of the MSM UV detector was enhanced by ∼10 folds. This work opens up new opportunities to design effective UV detectors for a variety of practical applications.

NIR Mitochondrial Fluorescent Probe for Visualizing SO2/Polarity in Drug Induced Inflammatory Mice

SO2 and polarity are important microenvironmental parameters in cells, which are closely related to physiological activities in organisms. The intracellular levels of SO2 and polarity are abnormal in inflammatory models. To this end, a novel near-infrared fluorescent probe BTHP that can simultaneously detect SO2 and polarity was studied. BTHP can sensitively detect polarity change with emission peak change from 677 to 818 nm. BTHP can also detect SO2 with fluorescence change from red to green. After addition of SO2, the fluorescence emission intensity ratio I517/I768 of the probe increased by about 33.6 times. BTHP can determine bisulfite in single crystal rock sugar with high recovery rate (99.2%-101.7%). Fluorescence imaging of cells showed that BTHP could better target mitochondria and monitor exogenous SO2 in A549 cells. More importantly, BTHP has been successfully used for dual channel monitoring SO2 and polarity in drug-induced inflammatory cells and mice. In particular, the probe showed increased green fluorescence with the generation of SO2 and increased red fluorescence with the decrease of polarity in inflammatory cells and mice.

Effects of ion temperature on detached plasma formation using a linear divertor simulator TPDsheet-U

The effect of ion cyclotron resonance heating (ICRH) on the detached plasma formation process was investigated using a linear divertor simulator, TPDsheet-U. We measured the stored energy (ion temperature), electron temperature, electron density, and Balmer series emission intensity ratio of the plasma while increasing the ICRH RF power from 0 to 400 W. It was observed for the first time that the electron temperature of detached plasma increased and the Balmer series emission intensity ratio became smaller when the ion temperature was increased by applying a resonance frequency ωRF, which is about 1.2 times the ion cyclotron frequency ωci of hydrogen ions. This suggests that increasing the ion temperature causes a transition from a detached plasma to an attached plasma.