Decrease In Emission Intensity Research Articles

Investigating the influence of carbon dots on β-Ca2SiO4:Ce3+ phosphors derived from agro-waste for diverse applications

A series of blue-emitting composite based on 3 wt% carbon dots in β-Ca2SiO4:Ce3+ (3 wt% CDs@β-CSO:Ce3+) was synthesized through a hydrothermal method, aiming to enhance applications in latent fingerprint (LFP) detection, anti-counterfeiting (AC) measures, and optical thermometry. The X-ray diffraction (XRD) analysis confirmed that these phosphors possess a monoclinic crystal structure. Under 356 nm excitation, the Ce3+ doped β-Ca2SiO4 phosphors (β-CSO:Ce3+) display a broad blue emission peak at 431 nm, attributed to the 5d → 4f electric dipole transition of Ce3+, while the inclusion of Carbon dots (CDs) shifts this emission to 442 nm. This shift and the improved photoluminescence (PL) intensity are thought to result from the Fӧrster Resonance Energy Transfer (FRET) mechanism. The optimal concentration of Ce3+ ions was determined to be 5 mol%, as higher concentrations led to a decrease in emission intensity due to concentration quenching (CQ). Additionally, a fabricated white light diode using these phosphors achieved chromaticity coordinates of (0.344, 0.330) according to the Commission International de L'Eclairage (CIE), with the CIE, correlated colour temperature (CCT), and colour purity (CP) metrics indicating a bright green output with values of (0.1486, 0.0433), 1759 K, and 96.4%, respectively. The optimized 3 wt% CDs@β-CSO:5Ce3+ composite demonstrated a remarkable CP of 99.9%. Notably, the phosphors maintained 85.77% of their emission intensity at 423 K, showcasing exceptional thermal stability. A novel approach utilizing sketch pen and brush mode was developed to apply the optimized AC security ink, allowing for the creation of various intricate patterns. The resulting AC tags featured high resolution and durability. These findings underscore the 3wt%CDs@β-CSO:5Ce3+ composite as superior luminescent materials for use in fields requiring LFP, AC strategies, and optical thermometry.

Synthesis and erudite insight into the structural, luminescence and thermal sensing characteristics of Sm3+ incorporated [formula omitted]-BaB2O4 novel phosphors

In this paper, we have presented the comprehensive characterization of red-light-emitting novel β-BaB2O4:xSm3+ (x = 0.5, 0.75, 1, 1.5, and 2 mol%) phosphor samples synthesized by making use of solid-state reaction method. The XRD patterns verified the successful synthesis and in-depth analyses were carried out to explore the structural, luminescence, and thermal properties. Notably, the introduction of Sm3+ through doping did not result in any substantial alterations in the crystal structure. Photoluminescence (PL) emission spectra exhibited 4 distinct peaks for 401 nm excitation. Out of these 4 peaks, the prominent peak was present at 601 nm, attributed to the magnetic dipole-allowed transition 4G5/2 → 6H7/2. The colorimetric analysis revealed the correlated color temperature (CCT) to be around 1700 K, accompanied by 99.9 % colour purity. The optimal doping concentration, before luminescence quenching, was identified as 1 mol%, with multipole-multipole interactions identified as the predominant quenching mechanism. Diffuse reflectance spectroscopy (DRS) studies on β-BaB2O4:1%Sm3+ confirmed characteristic peaks corresponding to Sm3+ transitions, revealing an ionic bonding nature between Sm3+ and the host. Also, the direct optical band gap was determined to be 5.62 eV. Furthermore, the optimized phosphor demonstrated exceptional temperature-dependent photoluminescent (TDPL) properties, exhibiting a negligible (∼5 %) decrease in emission intensity for prominent peaks even at 440 K. Overall, the phosphors displayed high activation energy, significant thermal stability, and thermal sensing properties, making them promising candidates for various optoelectronic applications.

Structural and Photoluminescence Properties of Ca2+-Substituted Self-Activated Photoluminescence Material of Na2TiSiO5

The effects of Ca2+ substitution on the structural and optical properties of Na2TiSiO5 were studied. It was expected that the Ca2+ ions would replace Na+ ions and change the coordination of Ti4+-O2- as a luminescence center. Na2(1‑x)CaxTiSiO5 (x = 0.00, 0.50, 1.00) samples were synthesized using the solid-state method, and their structural properties, the local Ti4+-O2- coordination, the absorption spectra, and the photoluminescence properties were studied. The electronic structure of Na2(1-x)CaxTiSiO5 with x = 0.00 and 1.00 was also calculated using the Full Potential Linear Augmented Plane Wave (FP-LAPW) method to explain some of the observed properties. The Ca2+ substitution resulted in a phase transformation from an orthorhombic to a monoclinic structure. The number of TiO6 octahedra increased with the increase of Ca2+ and correlated with the decrease of PL emission intensity of the Na2(1‑x)CaxTiSiO5 samples. The Ti-3d bands in the CaTiSiO5 were more dispersive than in the Na2TiSiO5 and were responsible for the PL emission intensity reduction.

Decomposition of Luminescent Hydroxyapatite Scaffolds in Simulated Body Fluid.

We present a luminescence study investigating the dissolution of rare-earth-doped hydroxyapatite scaffolds in simulated body fluid (SBF), aiming to assess the luminescence stability of Tb-, Ce-, and Eu-doped scaffolds over time. Our findings reveal a consistent decrease in luminescence emission intensity across all samples over a four-week period in which the scaffolds were immersed in the SBF. In addition, energy-dispersive spectroscopy confirms a decrease in rare-earth ion concentration in the scaffolds with respect to time, whereas fluorescence spectroscopy shows the presence of rare-earth ions in the SBF, indicating the partial dissolution of the scaffolds over time. The use of rare-earth ions as luminescence markers provides insights into the mechanisms of apatite formation in hydroxyapatites. Thus, these scaffolds may find wider use in regenerative medicine, particularly in targeted drug delivery systems, where their luminescent properties have the potential to noninvasively track drug release.

Assessing the impact of environmental performance on corporate financial performance: A firm-level study of GHG emissions in Africa

Utilizing comprehensive firm-level data from 2005 to 2021 across various African nations, our study investigates the effect of a firm's greenhouse gas (GHG) emissions on its corporate financial performance (CFP). The research yields the following findings. First, we find that GHG emission intensity exerts a significantly negative impact on CFP measured by return on assets (ROA) and return on equity (ROE). This effect is consistently substantiated across different measurements of GHG emission intensity and CFP. Second, our analysis includes a series of stringent robustness assessments, all of which affirm the stability and resilience of our primary findings. Third, following the Paris Agreement, a decrease in GHG emission intensity correlates with a further rise in ROA and ROE. Additionally, we emphasize the pivotal role of industry-specific characteristics and regional variables in shaping the connection between GHG emission intensity and CFP. Our findings underscore that the influence of GHG intensity on a firm's financial performance is particularly pronounced within high-emission sectors in contrast to their low-emission counterparts. Furthermore, we show that the impacts of GHG emission intensity on CFP are primarily driven by firms operating in Southern Africa. Fourth, to recognize potential endogeneity concerns within the GHG emission-CFP relationship, we employ a two-stage least-squares regression (2SLS) approach. This method utilizes industry-level GHG emission intensity as the principal instrumental variable (IV), and in order to further mitigate endogeneity issues, we incorporate both lagged GHG intensity and the instrument proposed by Lewbel (2012) based on heteroskedasticity as additional IVs alongside the kinky least squares method by Kiviet (2020). The results derived from our 2SLS estimates consistently corroborate the negative effect of GHG emission intensity on CFP. Finally, our empirical findings carry significant implications for both corporations and policymakers.

Moisture‐Resistant Orange Emitters with Near‐Unity Quantum Yield from Mn2+ Alloyed Vacancy‐Ordered Quadruple Perovskites

AbstractMn2+‐doped metal halide perovskites present remarkable optical properties in optoelectronic applications, although the realization of high efficiency and stability is still a challenge. In this work, a series of highly efficient and stable orange‐emitting Mn2+ alloyed Cs4Cd1‐xMnxBi2Cl12 single crystals are successfully synthesized via a hydrothermal reaction. Combined with the crystal structure and spectral characterization at 7 K, the site occupation of Mn2+ and defect emission are systematically discussed. Benefiting from the effective [BiCl6]3−→[MnCl6]4− energy transfer and lattice distortion, these single crystals exhibit a maximum internal and external quantum yield of ≈97% and ≈65% at 35% heavy doping level. Interestingly, these Mn2+‐alloyed single crystals exhibit remarkably waterproof stability, no decrease in emission intensity is observed after immersion in deionized water for 4 h. After soaking in deionized water for 100 days, the internal quantum yield can still maintain 44%, implying good chemical stability and moisture resistance due to the formation of protective BiOCl layer. This work provides new insights into the optimization mechanism for Mn2+ luminescence and overcoming the downside of their waterproofing in humid conditions.

Non-covalent interaction between soybean protein isolate and naringenin: Focused on binding mechanism, interface behavior, and functional properties

In this study, non-covalent complexes of soybean protein isolate (SPI)- Naringenin (Nar) with different concentrations of Nar were prepared, and their binding mechanisms and interfacial properties were investigated. The results showed that the content of α-helix and β-sheet in the SPI-Nar complex decreased to 19.62% and 26.58%, respectively. With an increase in Nar concentration, there was an increase in the ultraviolet absorption peak and a decrease in fluorescence emission intensity. Fluorescence quenching analysis revealed static quenching between Nar and SPI, with a binding site of 0.98, ΔG, ΔH, and ΔS had negative values. Molecular docking and molecular dynamics simulations indicated that Nar binds within the hydrophobic cavity of SPI. At a Nar addition amount of 1 mg/mL, the EAI and ESI of the SPI-Nar complex were 91.97 m2/g and 49.28 min, respectively. The foaming capacity and foam stability were 58.0% and 62.07%, respectively, and exhibited optimal air/water interfacial properties. The functional properties of the non-covalent complex were effectively improved, providing a theoretical basis for its application in the food industry.

Air pollutant emissions caused by receiving international industrial transfer in Southeast Asian developing countries from 1990 to 2018

Receiving international industrial transfer (mainly foreign direct investment, FDI) is extremely important for economic development but also brings negative environmental impacts for Southeast Asian developing countries (SEADCs). Due to relatively low labor costs and large market potential, SEADCs have become an attractive destination for industrial transfer after China, while studies were far from sufficient on the associated air pollutant emissions that would worsen air quality and threaten human health. We develop an exploratory framework to estimate the long-term trends of relevant air pollutant emissions in eight major SEADCs, including Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Thailand, and Vietnam. During 1990–2018, the emissions generally show a fluctuating upward trend and increased significantly in Cambodia, Laos, Philippines, and Vietnam. The total emissions of CO, NMVOC, SO2, NOX, PM2.5, and NH3 from the eight SEADCs increased from 19.0, 4.3, 3.6, 1.5, 0.5, and 0.4 kilotons (kt) to 391.6, 260.9, 271.1, 182.4, 48.4, and 12.2 kt, respectively. The emission growth in almost all SEADCs accelerated after 2008 and faster than FDI growth. The disparities in emissions among SEADCs basically grew first and then declined to a level lower than that of 1990, but generally exceeded the disparities in FDI. Productivity gain and emission intensity decrease primarily caused the emission growth and reduction, respectively. Relatively small reductions in emission intensity are found for NOX and SO2. In general, most SEADCs have utilized FDI for economic development without sufficient efforts on air pollutant emission controls. Our outcomes can inform the formulation and optimization of relevant policies reconciling economic development and air quality improvement in SEADCs.

Analysis of energy policy reform in Iran: Energy and emission intensity changes

The Subsidized energy system of Iran, with its high financial burden, failed to achieve its intended economic goals, resulting in increased energy consumption and pollutant emissions. Energy product subsidies in Iran are among the highest in the world and have important implications for developing countries. This study examines the impact of subsidy removal policy on energy and emission intensities using a Dynamic Computable General Equilibrium model. The findings reveal that after subsidy removal, total output experiences an annual growth of around 1.5%, with output composition changes mainly favoring agriculture and services that are less energy dependent. However, prices soar by at least 10% owing to the higher costs of energy products. The decreasing trend in energy intensity after subsidy reform is accompanied by a decrease in emission intensity. Higher prices of energy after subsidy removal and the corresponding improvement in the efficiency of energy consumption lead to lower emission intensity.

Does the green finance reform and innovation experimental zone policy reduce carbon emission intensity? Evidence from Chinese cities

The reduction of carbon emission intensity cannot be achieved without policy support, of which green financial policy is a major component. The main aim of this study is to discuss the causality between the green finance reform and innovation (GFRI) experimental zone policy and the intensity of carbon emissions in China. Using data from 265 Chinese cities from 2005 to 2021, this study applies a time-varying difference-in-differences (DID) model to assess the effect of the GFRI experimental zone policy on the intensity of carbon emissions. The heterogeneity of impacts and the parallel-serial mediation effect of this experimental zone policy are discussed further. The following main findings are obtained. (1) The GFRI experimental zone policy dramatically reduces carbon emission intensity, and this effect is more prominent in cities with large sizes of credit and bond finance. (2) After considering the heterogeneity of government environmental concerns and fiscal pressures, this study reveals that the effect of the GFRI experimental zone policy on reducing carbon emission intensity is weaker in cities with high numbers of environmental protection penalties and fiscal pressures. As the number of environmental penalties and fiscal pressures increases, the effect of the GFRI experimental zone policy on reducing carbon emission intensity decreases; that is, the phenomenon of environmental protection paradoxes and policy conflicts has emerged. (3) Increasing financing for green projects and decreasing the energy intensity of the industry are the primary mediating channels for GFRI experimental zone policy to reduce carbon emission intensity, but the mediating channels for boosting green innovation and promoting energy structure adjustment are not prominent. Moreover, the total effect of the GFRI experimental zone policy on reducing carbon emission intensity is 72% direct and more than 20% indirect. This study concludes that in regions with high fiscal pressure, governments should rely more on green finance to decrease carbon emission intensity. Meanwhile, a green finance policy must be more supportive of zero-carbon energy production and reduce direct environmental penalties to decrease carbon emission intensity in the future.

What is the Impact of Fiscal Technology Expenditure on Carbon Emission Reduction? Evidence from Guangdong Province in China

China has put forward the strategic goal of striving to achieve peak carbon by 2030 and carbon neutrality by 2060, and reducing carbon emission intensity is a top priority. This paper analyses the impact of local government fiscal science and technology expenditures on carbon emission intensity based on a fixed panel regression model using panel data of 21 cities in Guangdong Province from 2000 to 2019, and draws the following main conclusions: (1) Higher fiscal science and technology expenditures significantly promote the reduction of carbon emission intensity. Specifically, for every 1% increase in expenditures, the carbon emission intensity decreases by 0.221%; (2) The mechanism includes promoting the level of green innovation and promoting the level of new and high technology. Therefore, local governments should pay attention to the role of environment-friendly science and technology innovation on low-carbon development, help glow-carbon research and application transformation, strengthen the regulation of heavy polluting enterprises, and guide the capital to green industries, so as to embark a new road of high-quality economic development and carbon reduction.

Defect Induced high-color-rendering white light emissions from Ag-doped ZnO

It is crucial to find high-quality white-light phosphors that are simple to synthesize in order to create efficient lighting. In this pursuit, the focus has been on achieving the emission of white light in ZnO and Ag-doped ZnO emerging as a promising phosphor candidate. The optimized ZnO nano phosphors demonstrated visible-light emission with ideal Commission international de I E “Eclairage frequently abbreviated as coordinates (x = 0.33, y = 0.33 ) and a correlated color temperature of 6200 K, and a color rendering index of 100 for equivalent to day white light. Furthermore, under certain ideal processing conditions, neutral white-light emission (x = 0.33, y = 0.33 at λex = 280 and 370 nm) with a Color correlated temperature (CCT) of 5500 K(approx.) was achieved. The Color Rendering Index (CRI) of the ZnO and Ag:ZnO nanoparticles exceeded 90, with high values approaching 96%, which is necessary for accurately portraying object colors in comparison to natural sunshine. The research findings revealed a decrease in the FS emission intensity with all the UV excitation when Ag doped in ZnO, which aligns well with the principles of Stern-Volmer quenching. A reduction in intensity was observed which may be due to the Ag dopant interacting with the luminescent nanoparticles and causing a reduction in their emitted light. The study successfully develops and optimizes ZnO-based nano phosphors with tailored white-light emission characteristics, presenting a promising solution for achieving energy-efficient and high-quality white-light sources for various lighting applications.

Impacts of ultraviolet and photosynthetically active radiations on photosynthetic efficiency and antioxidant systems of the cyanobacterium Spirulina subsalsa HKAR-19.

This study summarizes the response of cyanobacterium Spirulina subsalsa HKAR-19 under simulated light conditions of photosynthetically active radiation (PAR), PAR+UV-A (PA), and PAR+UV-A+UV-B (PAB). Exposure to UV radiation caused a significant (P < 0.05) decrease in chlorophyll a, phycocyanin, and total protein. In contrast, total carotene content increased significantly (P < 0.05) under PA and PAB with increasing irradiation time. The photosynthetic efficiency of photosystem II also decreased significantly in PA and PAB radiation. We havealso recorded a decrease in the fluorescence emission intensity of phycocyanin under PA and PAB exposure. The phycocyanin fluorescence shifted towards shorter wavelengths (blue-shift) after 72h of PA and PAB exposure. Intracellular reactive oxygen species (ROS) levels increased significantly in PA and PAB. Fluorescence microscopic images showed an increase in green fluorescence, indicating ROS generation in UV radiation. We havealso quantified ROS generation using green and red fluorescence ratio represented as G/R ratio. A 2-6-foldincrease in antioxidative enzymes activity was observed to overcome the damaging effects caused by UV stress as compared to untreated control cultures. The lipid peroxidation was assessed in terms of malondialdehyde content which increases significantly (P < 0.05) as the duration of exposure increases. These results suggest that a combined effect of PAR, UV-A, and UV-B was more deleterious than an individual one.

The Impact of Industrial Added Value on Energy Consumption and Carbon Dioxide Emissions: A Case Study of China

China, as the world’s largest energy consumer, is faced with the growing pressure of carbon emission reduction. Promoting the sustainable transformation of the economy and society has become a major concern for all sectors of society. This paper assesses the potential impacts of industrial added value on energy consumption and carbon dioxide (CO2) emissions from 2010 to 2020 in China using a multi-objective, linear programming model. The results show that when the industrial energy consumption is 3695.17 Mtce and the industrial CO2 emission is 9364.16 Mt, the goal of energy saving and emission reduction can be achieved. This corresponds to an annual average growth rate limit of industrial added value of 7.8%. In addition, we find that when the annual average growth rate of industrial added value is greater than 9.9%, changes in the annual average growth rate of industrial added value have no impact on economic development. However, industrial energy consumption intensity and industrial carbon emission intensity decrease with the increase in the annual average growth rate of sub-sectors. This study proposes that energy conservation, emission reduction, and a realization of the sustainable transformation of industry scheme need to be achieved by the Chinese government in order to to continue to promote the development of several sectors with low industrial energy consumption intensity and low industrial carbon emission intensity through policy implications.

Analyzing long-term dynamics of agricultural greenhouse gas emissions in Austria, 1830–2018

Agriculture is an important contributor to greenhouse gas (GHG) emissions. While the development of agricultural GHG emissions on national and global scales is well studied for the last three to six decades, little is known about their trajectory and drivers over longer periods. In this article, we address this research gap by calculating and analyzing GHG emissions related to agriculture in Austria from 1830 to 2018. We calculate territorial emissions on an annual basis and include all GHG emissions from the processes directly involved in agricultural production. Based on this time series, we quantify the relative importance of major drivers of changes in GHG emissions across time and agricultural product categories, applying a structural decomposition analysis. We find that agricultural GHG emissions in Austria increased by 69 % over the total study period, from 4.6 Mt. CO2e/yr in 1830 to 7.7 Mt. CO2e/yr in 2018. While emissions increased only moderately from 1830 to 1945 (+22 % overall), with strong fluctuations between 1914 and 1945, they doubled from 1945 to 1985. In the most recent period from 1985 to 2018, emissions fell by one third, with decreases leveling off over time. Our decomposition analysis reveals that increases in agricultural production per capita most importantly contributed to the high growth in GHG emissions from 1945 to 1985. Conversely, decreasing emission intensities of products and a more climate friendly product mix were key drivers in the emissions reduction observed after 1985. We also contribute to the discussion around the global warming potential star (GWP*), by calculating GHG emissions based on this alternative metric, and contextualize our data within total socio-economic GHG emission trends. By providing insights into the historical trends and drivers of agricultural GHG emissions, our findings enhance the understanding of their long-term historical dynamics and adds to the knowledge base for future mitigation efforts.

How does government efficiency affect carbon emission intensity? A comprehensive empirical study.

This study utilized panel data from 132 countries spanning from 1996 to 2019 to examine the effect of government efficiency on carbon emission intensity. Using a fixed effect model, the study found that stronger government efficiency is associated with a significant decrease in carbon emission intensity. Robustness tests were performed, the results of which consistently supported the main findings. Additionally, the study investigated the mechanisms underlying the linkage between government efficiency and carbon emission intensity, revealing that improved government efficiency can inhibit carbon emission intensity by fostering environmental innovation and promoting renewable energy consumption. Finally, the study examined the moderating effects of national income level, economic freedom, democracy, and ruling party ideology on the nexus of government efficiency and carbon emission intensity, and found empirical evidence supporting these moderating effects. These results provide new insights for governments seeking to reduce carbon emission intensity.

The borophene quantum dots scaffolded TiO2 nanocomposite as an efficient photo electrocatalyst for water splitting application

Herein, we are scaffolding borophene quantum dots (BPQDs) on photoactive semiconductor nanomaterial such as TiO2 nanoparticle which shows enhanced photoelectrochemical (PEC) water splitting activity. The BPQDs are synthesized by sonochemical method and then scaffolded onto TiO2 nanoparticles by hydrothermal method. Further, the concentration of BPQDs on TiO2 nanoparticles is optimized for better photoelectrochemical water splitting application. The effective absorption edge is found to be less (2.51 eV) for 2.5 wt% BPQDs scaffolded TiO2 nanoparticles as studied by UV–Visible spectroscopic analysis. Transmission electron microscopic (TEM) images reveal the scaffolding of BPQDs of size (2–9) nm with TiO2 nanoparticles of having the size ∼25 nm. XRD results confirmed the anatase phase of TiO2 nanoparticles and b-rhombohedral boron structure for BPQDs. The FTIR and XPS results confirms the presence of boron functionalized groups in the nanocomposites. The photoluminescence (PL) spectroscopic results revealed the decrease in PL emission intensity for BPQDs/TiO2 nanocomposite indicating the decreased photogenerated charge carriers recombination time. The work function (ϕ) is found to be less for BPQDs/TiO2 nanocomposite signifying the easy release of electrons under the presence of visible light illumination. Further, BPQDs/TiO2 nanocomposite shows the improvement in photoelectrochemical (PEC) water splitting due to the synergistic effects of individual components.

Carbon pricing and firms’ GHG emissions: Firm-level empirical evidence from East Asia

This study investigates the impacts of carbon pricing policies on firms' greenhouse gas (GHG) emissions. We include two carbon pricing policies: carbon tax and emission trading scheme (ETS) at national and sub-national (province) levels, measured as policy existence (binary variable) and carbon price (continuous variable). Firms' GHG emissions are measured as total emissions and emission intensity. Using unique recent firm-level data from 2010 to 2021 from three East Asia countries (Japan, the Republic of Korea (ROK), and the People's Republic of China (PRC)), we obtain the following key findings. First, the national carbon pricing policy significantly reduced firms' GHG emissions and GHG emission intensity in Japan and the ROK. The greater the carbon price, the greater the impact. Second, the subnational carbon pricing policies implemented in two provinces of Japan (Saitama and Tokyo) decreased firms' GHG emissions. Third, heavy industry sectors such as energy, utilities, and industrials experienced a substantial decrease in GHG emission intensity due to the carbon pricing policy. Finally, our main results are robust to different model specifications and various measures of firms' GHG emissions. Although literature studying the ex-post impact of carbon pricing on emissions at country and sector-level is abundant, this paper contributes to the existing literature providing empirical evidence of the impact of carbon pricing policies on firms' emissions using firm-level data, which is highly limited especially in Asia.

Simulation study on influence of oxygen concentrations on atmospheric-pressure streamer in oxygen-rich nitrogen–oxygen mixture

This study aims to investigate the behaviour of positive streamer discharge in various mixtures with different concentrations via two-dimensional simulations. The proposed model considers the effects of photoionisation caused by the photons generated by excited oxygen atoms , which enables the simulation of streamers in oxygen rich conditions. The simulation results indicate that the propagation velocity and diameter of the streamer increase with the oxygen concentration, while the emission intensity decreases. The result conforms to the experimental results of our previous work. Moreover, the simulation results suggest that changes in the ionisation rate caused by variations in the oxygen concentration affect the streamer propagation, while the impact of photoionisation is limited.

Bimetallic Eu/Tb Complexes for Ratiometric Temperature Sensing with Unusual Enhancement of Eu Luminescence with Temperature

In this paper we describe the results of the influence of temperature in the range of 280–340 K on the luminescence of bimetallic Eu/Tb complexes with N-heterocyclic ligand L based on 2,2′-bipyridyldicarboxylic acid in acetonitrile. The experiments were carried out for systems with various Eu/Tb ratios. The stability of the complexes of the ligand L with metal M (Eu or Tb) was determined using spectrophotometric titration in acetonitrile solutions. The LM complexes’ stability constants were found to be typical for these systems; however, the stability of Eu complex is slightly higher than that for Tb. Along with rising temperature, we observed a decrease in Tb emission intensity and, at the same time, an enhancement in Eu luminescence. An explanation of Eu luminescence enhancement involves the appearance of charge transfer states, bands of which can be observed in the Eu luminescence excitation spectra as difference spectra measured with two close temperatures. The unusual Eu luminescence enhancement upon heating was observed for the first time for the complex with tetradentate O,N-type heterocyclic diamide ligand L, while an inverse phenomenon was observed with the Tb luminescence. The Eu luminescence enhancement was found earlier for various carboxylate complex salts, but not for heterocyclic coordination complexes. This allows the construction of a ratiometric luminescent thermometer in the range of 280–340 K using the ratio of luminescence intensities for Eu and Tb. The stability constants for the individual Eu and Tb complexes help us to understand the equilibrium in L:Tb:Eu complex system and shed light on plausible speciation in solution.