COORDINATION COMPLEX [Eu(μ 2 -OC 2 H 5 )(btfa)(NO 3 ) (phen)] 2 ·phen WITH HIGH LUMINESCENT EFFICIENCY

Experimental results on the bis[(μ 2 -etoxi)(benzoyl trifluoroacetonato)(nitrato)(1,10- phenantroline)europium(III)]1,10-phenantroline europium(III) coordination complex (hereafter, [Eu(μ 2 -OC 2 H 5 )(btfa)(NO 3 )(phen)] 2 ·phen) are described. The complex is characterized by photoluminescence (PL) and infrared spectroscopy. Photoluminescence spectra of the complex exhibit strong emission with specific narrow emission bands associated with the 5 D 0 → 7 F j (j = 0–4) transitions. The pattern of emission band splitting and the luminescence time decay suggest the presence of at least two different sites of the Eu 3+ ion in a low-symmetry environment. The absolute PL quantum yield of the complex is determined to be 49.2%.

Experimental research on the mechanism of chemical energy conversion to light energy under thermal induction

Since the discovery of glare illuminators, considerable efforts have been devoted to achieving a breakthrough of high light intensity on the order of magnitude. In this paper, we prepared strong flash blinding agents for the first time by using aluminum powder, oxidant, and adhesive as the main materials, and tris-(8-hydroxyquinolinato) aluminum (Al2q3), triazoindolizine, or nano zinc oxide, etc. as electronic output brightener after mixing and granulation according to the developed formulation. It was discovered that the luminescence intensity was related to the thermal effect of the substance while the brightener only served as an auxiliary brightening effect to achieve energy non-destructive conversion. With the same formula, the luminescence intensities of glaze agents with ADN and potassium perchlorate as oxidants were slightly higher than that of ammonium perchlorate oxidant; the brightening effect of nano-zinc oxide was slightly higher than those of tris-(8-hydroxyquinolinato) aluminum (Al2q3) and triazoindolizine. The luminescence intensity of the substance with a high thermal effect value was high, but the luminescence time was slightly short. Under identical conditions, the luminescence effect of nano-aluminum powder was obviously better than that of micro-aluminum powder with the highest luminescence intensity of 3.9 × 1010 ~ 1.9 × 1011 cd and the luminescence time of 39 - 48 ms. The effects of shell material and structure and the effect of heat-induced mode on the luminescence intensity were also investigated. The luminescence intensity of the glare agent with a high shell strength was high, but the luminescence time was slightly short. Moreover, the energy level of the brightener is excited under the induction of high temperatures, which leads to a blue shift to promote the chemical reaction of the material in a favorable direction. Finally, the optical radiation of the thermally induced high-temperature combustion system was analyzed from the aspects of thermal effect, combustion temperature, and chemiluminescence effect. A way to improve the optical radiation intensity of a high-temperature combustion system was proposed.

TiO2-CdS Nanocomposites: Effect of CdS Oxidation on the Photocatalytic Activity

Nanocomposites TiO2-CdS with different relative contents of CdS (molar ratios Cd/Ti = 0.02, 0.03, 0.05, 0.1, 0.2, and 0.5) were studied. The structural, photophysical, and chemical properties were investigated using XRD, Raman spectroscopy, XPS, GSDR, and LIL. XRD and Raman results confirmed the presence of TiO2 and CdS with intensities dependent on the ratio Cd/Ti. The presence of CdSO4 was detected by XPS at the surface of all TiO2-CdS composites. The relative amount of sulphate was dependent on the CdS loading. Luminescence time-resolved spectra clearly proved the existence of an excitation transfer process from CdS to TiO2 through the luminescence emission from TiO2 after excitation of CdS at λexc=410 nm, where no direct excitation of TiO2 occurs. Photodegradation of a series of aromatic carboxylic acids—benzoic, salicylic, 4-bromobenzoic, 3-phenylpropionic, and veratric acids—showed a great enhancement in the photocatalytic efficiency of the TiO2-CdS composites, which is due, mainly, to the effect of the charge carriers’ increased lifetime. In addition, it was shown that the oxidation of CdS to CdSO4 did not result in the deactivation of the photocatalytic properties and even contributed to enhance the degradation efficiency.

Heterogeneity Influence of Organic Matter on the Ozonation Chemiluminescence for Soils and Sediments

Organic matter in soils and sediments is the key object of biogeochemistry in both terrestrial and marine ecosystems. Whether organic matter is the source or sink of carbon and nutrients can be predicted by its compositions and need continuous, long-term observations of organic matter compositions; therefore, in situ technologies are being investigated to meet the continuous, long-term observations. This study tried to explore a rapid determination of organic matter compositions by ozone chemiluminescence. After the soils or sediments were oxidized by ozone, their chemiluminescence characteristics such as luminescence maximum and time differed significantly. We hypothesized that the luminescence characteristics is controlled by the organic matter compositions. The soils and sediments were separated into extractives, acid soluble fractions (AS), and acid insoluble fractions (AIF), and then the original samples and their compositions were oxidized by ozone. Different organic matter compositions play a different role in the luminescence characteristics: extractives inhibited the luminescence maximum and luminescence time, AS increased the luminescence time and AIF increased the luminescence maximum. Results also showed that AIF can explain most variation of luminescence characteristics, suggesting that the luminescence characteristics are mainly controlled by the concentrations of AIF. Our study suggested that ozonaiton chemiluminescence have a strong potential to rapidly determine the chemistry of soils and sediments.

Study on Novel Method to Measure Luminescence Time Interval Between the Initial and Terminal of Light Emission in Frequency Domain

In this paper, a novel method to measure the luminescence time interval between the initial and terminal of light emission in frequency domain is proposed. Under the condition that the time of excitation pulse is equal to the luminescence time interval between the initial and terminal of light emission, the energy of excitation is complete dynamically balanced by the light emission and the maximum luminescence intensity can be achieved. So the luminescence time interval between the initial and terminal of light emission can be expressed as (is the driving frequency which is corresponding to the maximum luminescence intensity). The luminescence time interval between the initial and terminal of light emission () of Alq3 (Tris-(8-quinolinolato)aluminum) is [s] measured using the novel method.

Effect of B2O3 on Long-Last Phosphorescence of SrAl2O4:Eu2+,Dy3+

A series of Sr0.95Al2O4:Eu2+0.02, Dy3+ 0.03•nB2O3 (0≤n≤0.30) were prepared by a solid state reaction. The role of B2O3 on the photoluminescence (PL) properties of Sr0.95Al2O4:Eu2+0.02, Dy3+0.03 were evaluated with UV emission spectra and decay curves. B2O3 significantly improved the emission intensity and persistent luminescence time. The crystal environment and defects induced by B3+ doping were detected with IR spectra, thermoluminescence and positron annihilation (PA) methods. Some Al3+ were substituted by B3+ and a kind of defect complex cluster responsible for the long decay time was formed when the substitution of Al3+ by B3+ occurs.

Nonequilibrium Carrier Dynamics Studied in Er, O-Codoped GaAs by Pump-Probe Reflection Technique

Carrier dynamics in Er,O-codoped GaAs (GaAs:Er,O) have been systematically investigated by means of a pump and probe reflection technique with a mode-locked Ti:sapphire laser. In GaAs:Er,O, it has been found that the codoping produces a single atom configuration (Er-20 configuration) as an Er atom located at the Ga sublattice with two adjacent O atoms together with two As atoms, resulting in extremely strong Er luminescence. Time-resolved reflectivity of GaAs:Er,O exhibited an abrupt increase in amplitude, followed by a steep decrease to negative in less than 1 ps and then a gradual increase in approximately 100 ps. The steep decrease is due to bandgap renormalization. The gradual increase in reflectivity depended strongly on Er concentration, indicating that a trap induced by Er and O codoping plays an important role in dynamics of nonequilibrium carriers in GaAs:Er,O.