[en] Greenhouse, laboratory, and field studies were conducted to investigate the activity of soil and foliar applied chlorimuron on yellow and purple nutsedge. Soil-applied chlorimuron (10 to 60 g/ha) significantly decreased tuber sprouting, shoot emergence, and shoot growth in both yellow and purple nutsedge. Previous exposure to soil-applied chlorimuron was not effective in reducing parent tuber sprouting at any rate in yellow nutsedge, while in purple nutsedge parent tuber sprouting was reduced significantly at 60 g/ha. Shoots of both yellow and purple nutsedge propagules absorbed greater amounts of ¹⁴C than did roots and tubers. However, translocation of ¹⁴C was greater from the roots and tuber than from the shoot. Toxicity of foliar-applied chlorimuron (5 to 30 g/ha) was evident by stunted growth, leaf discoloration, and death in both species. Application of chlorimuron at 20 g/ha gave 84% control in yellow nutsedge and 100% control in purple nutsedge. Chlorimuron treatments reduced shoot dry weight, inhibited secondary shoot production, and killed parent tubers attached to treated plants, regardless of rats, in both species. Over 13% of the foliar-applied ¹⁴C recovered was absorbed and over 15% of that absorbed was translocated at 1 day after application in both species. This increased two-fold by 8 days after application. ¹⁴C translocation was both acropetal and basipetal. Over 68% of the absorbed ¹⁴C in yellow nutsedge and 63% in purple nutsedge was retained in the treated area at 8 days after application. Overall, the basal bulb, rhizomes, and tuber had the least amounts of ¹⁴C in both species

[en] In order to understand the role of impurities and the nature of traps that are produced in these activated NaYF/sub 4/ phosphors by ionizing radiations like X-rays, a comprehensive programme has been undertaken in the laboratory to prepare and study their luminescent and electrical properties. These studies are motivated not only to understand the involved electronic process but also to explore the possibilities of using them in dosimetry. In this paper the results on X-ray induced thermally stimulated Luminescence (TSL) of NaYF/sub 4/ are analyzed

[en] Glow curves were recorded for NaCl:Sr²⁺ crystals subjected to annealing and quenching from elevated temperatures. These specimens were irradiated with X-rays at room temperature by tungsten target. Samples exhibit certain glow peaks which are observed only in the first thermal cycle. A marked difference in the glow curves pattern for first and subsequent thermal cycles has been observed. It is suggested that these changes may be due to the change in configurational coordinate system of F-centre due to impurity existing different states. This idea is supported by optical microscopy studies. (author)

[en] In the present investigation, we have attempted to study the production of Z₂-centres in X-irradiated Gd²⁺ doped NaCl crystals. NaCl crystals containing 1 mol% Gd²⁺ were grown in our laboratory in a platinum crucible by Kyropoulos technique. Single crystals were used for optical absorption and TL studies. All the specimens were X-irradiated at room temperature. For producing Z₂-centres, the samples are irradiated and bleached with F-light and then kept at 100 deg C in a furnace for about 10 min. The TL glow curve of NaCl crystal containing 1 mol% of Gd²⁺ irradiated with X-rays for 10 min is shown. In this a small peak around 55 deg C, a shoulder around 125 deg C and a prominent peak around 195 deg C are observed. In order to study the luminescent centres responsible for these peaks, F-bleaching studies were carried out. The results are discussed. (U.K.)

[en] Elevated irradiation temperature studies with NaYF₄ samples reveal that the intensity of the two glow peaks observed around 120 and 180 ⁰C enhances. The effect of temperature of irradiation on the sensitisation of the both peaks is studied. The half lives of these glow peaks were calculated and it was concluded that the half lives of these peaks decrease with the increase in irradiation temperatures. (author)

[en] Radiation hardening studies of undoped NaCl and NaCl crystals doped with barium have been carried out both in the as-grown state and after quenching them for 650 ⁰C. It is observed that the radiation hardening is more in doped crystals and the results are explained taking into consideration the role of Z₁-centres. (author)

[en] Thermal annealing of X-irradiation induced point defects in yttrium-doped KBr crystals is investigated by thermoluminescence (TL). The results of the influence of pre-heat treatment, optical bleaching, and impurity concentration on glow curves are discussed. In KBr containing 1 mol% yttrium, three glow peaks around 80, 100, and 125deg C are observed. Quenching of the crystal from high temperature results in the suppression of the first two peaks and shifting of the last peak from 125 to 95deg C. The first peak is attributed to the background impurities, the 100deg C peak to yttrium centres, and the 125deg C peak to F-centres. The shifting of the high temperature peak on quenching is attributed to the impurity present in different states of dispersion surrounding F-centres. (author)

[en] In a previous report an attempt was made to explain the luminescent nature of NaYF₄ phosphor through thermoluminescence (TL) studies. The activation parameters and escape frequency were determined using all available equations assuming the first order kinetics, but from the work of other workers, it was realized that the TL of many ionic solids follow complex kinetic orders. Thus, it was decided to investigate the order of kinetics of TL of NaYF₄ pellets more precisely by the isothermal decay method and compare the result obtained with the glow peak shape method. The samples were irradiated with X-rays. Experimental details are given. Results are given and discussed. (author)

[en] Effects of post-irradiation on thermoluminescence (TL) of NaCl crystals doped with Ba have been studied. It is shown that the 180 ⁰C TL peak is not present in the as-irradiated sample can be generated by post-irradiation deformation

[en] By monitoring the type of defects in fluorite structure compounds there exists a possibility of controlling some structure dependent properties. The electrical properties of vitreous NaYF₄ thin films obtained by thermal evaporation have been studied. The current-voltage characteristics of Al-NaYF₄-Al structures for different thicknesses of films and at different temperatures are shown. The values of the breakdown voltage and brakdown field strength for different thicknesses are listed. The slopes of measured curves of electrical conductance as function of temperature give the activation energies. The large value of the activation energy in the region of high temperatures shows that the conduction through the film is caused mainly by F^- ions rather than electrons