Analysis of the thermoluminescent of borate glass by computerized glow curve deconvolution in kinetic formalism

Borate based phosphor is a suitable material for thermoluminescence dosimetry. Glow curves of β-irradiated pure borate glass has been analyzed by restoring to Computerized Glow Curve Deconvolution (CGCD) technique and evaluate the trapping parameters namely activation energy (E), frequency factor (s) and order of kinetics (b). It is observed that there are stable peaks in the range 110° to 150°C even to various extent of thermal cleaned ones also. The activation energies of the phosphor are in the range 0.898 to 1.325 eV and frequency factors are in the order of 1011 to 1013 s−1.

ANALYSIS OF THERMOLUMINESCENCE GLOW CURVES RECORDED UNDER THE HYPERBOLIC HEATING SCHEME BY USING AN ALTERNATIVE CONCEPT OF SYMMETRY

Usually, the order of kinetics of thermoluminescence (TL) glow curve is evaluated by using the concept of traditional symmetry factor (μ_g) in which only three points of a glow curve are used. From the statistical point of view of the reliability of any method of analysis of glow, curve improves if instead of a few points the method can use a larger portion of the glow curve. In the present work, a technique is proposed to determine the order of kinetics associated with a TL peak by using the concept of skewness. The method is applied to experimental thermoluminescence (TL) curves recorded in a hyperbolic heating scheme.

Three-Point Area Method for Thermoluminescence Glow Curve Analysis and Its Application to the Glow Peak of K2SrP2O7:Pr

A method has been proposed to evaluate the kinetic parameters, viz. activation energy ($E$) and order of kinetics ($b$) from a single or isolated thermoluminescence (TL) glow peak. Along with the area under the entire curve, this method uses a set of three arbitrary data points and calculates the partial area under the curve from each point to the endpoint. In this way, the entire information associated with the curve is used and the method is named as ‘Three-Point Area’ (TPA) method. We have applied it successfully on a number of theoretically simulated TL curves generated in One Trap One Recombination centre (OTOR) model and General-Order Kinetics (GOK) model under quasi-equilibrium approximations with linear heating scheme. The activation energies are found in good agreement with input values for both the models. For OTOR model, temperature average of order of kinetics is estimated to compare with the present result. Systematic analysis is carried out for estimation of errors inherent in the method in the purview of GOK model. A closer look on the results reveals that any set of three points, preferably chosen from the rising side of the curve, can yield activation energy and order of kinetics. The validity of the method to extract $E$ and $b$ from experimental glow curves is exemplified by considering experimental TL data reported in literature. Finally, a complete study starting from the synthesis of a new phosphor $\mathrm{K_2SrP_2O_7:Pr} $ and analysis of the recorded TL data to estimate $E$ and $b$ employing the TPA method has been reported.

Determination of the Order of Kinetics of a DTA Curve by Using the Concept of Skewness

In the present paper, a novel way of finding out the order of kinetics of differential thermal analysis (DTA) curves by using the concept of skewness (Sk) has been investigated. It is found that for a particular DTA peak, skewness is a function of both the order of kinetics and the quantity, First order DTA peaks are characterized by negative skewness whereas those for the second order are characterized by positive skewness. Therefore, skewness can be used as an indicator of the order of kinetics of a DTA peak. We have evaluated and compared the orders of kinetics of some reported DTA peaks using the concept of skewness and found that the resulting values of the orders of kinetics are in fair agreement with those reported in literature.

The Dissipation of Cyazofamid and Its Main Metabolite CCIM during Wine-Making Process

Few studies have focused on the residues of cyazofamid and its main metabolite CCIM (4-chloro-5-p-tolylimidazole-2-carbonitrile) in the wine making process, which is crucial to evaluate the potential food risk of cyazofamid and CCIM. In this work, detailed study has been conducted on the evaluation of the fate of cyazofamid and its main metabolite CCIM during the wine-making process. The targeted compounds cyazofamid and CCIM were separated and determined by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) and processing procedure including washing, peeling, fermentation, and clarification. Results showed that residues of cyazofamid and CCIM decreased significantly in wine processing. The dissipation of cyazofamid in the fermentation process followed the first-order of kinetics, and the half-life of cyazofamid was 46.2–63.0 h, whereas, the residues of CCIM, in the three treatments, decreased with time elapse. The processing factors (PFs) were all less than one in different processing processes, and the PFs ranges of cyazofamid and CCIM were 0.003–0.025 and 0.039–0.067 in three treatments in the overall process. The outcome indicated that the whole process could significantly reduce the residues of cyazofamid and CCIM in red and white wines. The results might provide more precise risk assessments of cyazofamid in the wine-making process.

An Overview on Peak Shape Method for Thermoluminescence Glow Curve Analysis

The shape of a thermoluminescence (TL) glow curve has fundamental importance for calculating the characteristic parameters of trap levels within the band gap. TL analysis are mostly based on the three-parameter general order kinetics model. The parameters are activation energy, order of kinetics, and frequency factor. Peak shape method is one of the most prominent methods for extracting the activation energy from a TL curve. An overview of different peak shape methods along with an alternative approach formulated directly from basic TL equations is presented in this chapter. Generally, peak shape method requires prior knowledge of order of kinetics to determine activation energy which creates a difficulty due to the non-uniqueness of symmetry factor for a particular value of order of kinetics. A modified version of peak shape method which is free from this constraint is discussed here. Activation energies from experimental curves of tremolite and actinolite are estimated using peak shape method. Limitation of peak shape method for saturated TL peaks with heavy retrapping is also discussed.