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Room-temperature solid-matrix luminescence was investigated for two model compounds pyrene and 1-hydroxypyrene from optically clear sugar glasses. Several glasses were investigated. Novel glasses were prepared for the first time from binary mixtures of sugars for spectroscopy. Glasses were prepared from glucose/xylose and glucose/maltose. The glucose/maltose gave a superior glass compared to glucose/xylose. The glucose/maltose glass gave the best room temperature phosphorescence (RTP) for pyrene compared to glasses of glucose and maltose without a heavy atom. The RTP was weak for both pyrene and 1-hydroxypyrene without a heavy atom in the glucose glass. The addition of a heavy atom (12% NaI) gave a 44-fold increase in RTP of pyrene and a 10-fold increase in the RTP of 1-hydroxypyrene. Room temperature fluorescence (RTF) of pyrene and 1-hydroxypyrene were easily observed from all the glass systems studied. However, the pyrene RTF intensity varied with the different sugar glass systems studied. Furthermore, a polymer, polyacrylic acid (PAA), was added to the sugar matrix at the level of 1% and 2% to improve the rigidity of the glass matrix. The observed phosphorescence was weak for pyrene at both the 1% and 2% PAA concentrations. A glass prepared with 2% PAA gave the strongest RTP for pyrene. Addition of 12% NaI with 1% polyacrylic acid did improve the RTP of pyrene but it was less than the RTP of pyrene from a glucose glass with 12% NaI by a factor of 2.7. A glucose glass with 12% NaI was the best system for RTP of pyrene. 相似文献
164.
Practical silicon photonic interconnects become possible nowadays after the realization of the practical silicon light sources,where the hybrid integrations of Ⅲ-Ⅴ semiconductors and silicon by bonding... 相似文献
165.
电介质物理中的慢效应 总被引:2,自引:0,他引:2
熟知的凝聚物质各种物理效应均限于快效应。还存在完全不同的另一类效应,称为慢效应;它既不遵守已被公认的普通理论,甚至也不能用传统的方法来描述。文章以电介质的介电、压电和热释电等效应为例综述慢效应研究的进展;并评论其在科学技术各领域可能带来的影响。 相似文献
166.
Depolarization current characteristics of solution grown pure ethyl cellulose (EC) films of about 20μm thickness have been studied as a function of electrode materials at constant poling field (5 × 104 V/cm) and poling temperature 40°C. Thermally stimulated current (TSC) thermograms of EC consists of two well resolved peaks
(located at 60°C and 140°C) for Al-Al system, which are attributed to the deorientation of strongly attached ethoxy groups
of glycosidal units and diffusion of space charges either at electrodes or due to their thermal release at higher temperatures
from the defect levels. For dissimilar electrode combinations (Al-Ag/Cu/Au/Sn/Pb), an indication of peak of lower magnitude
at around (50–70°C) alongwith a higher temperature peak (140–155°C), have been observed. TSC parameters are found to change
with the choice of electrode material. The dependence of dark current at 40°C in metal-ethyl cellulose-metal systems on applied
voltage in the range (2·0–5·0) × 104V/cm has also been studied. The results of current-voltage measurement on EC have been interpreted to show that the Schottky-Richardson
mechanism is the controlling transport mechanism. Zero field current density extrapolated fromI-E
1/2 plots are found to vary with metal work function. 相似文献
167.
Electrodes modified by polythiophenes bearing different substituents have been prepared and the behaviour of the conducting polymers has been studied with respect to the structural phenomena occurring in the correspondence to the doping and the relevant undoping processes. The effects of experimental parameters, such as undoping potential and time, have been investigated. The steric hindrance of the substituents on the polymer chain is demonstrated to play a fundamental role in determining the extent of compactness of the film, as induced by polarisation of the electrode at potentials at which the previously charged polymer is neutralised. Such a conclusion is in accordance with prediction of the electrochemical stimulated conformational relaxation model. Electrochemical AFM measurements have been performed in order to acquire a direct view of the morphological modifications of the polymer coatings during the reduction. 相似文献
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用Nd1YAG激光器泵浦光学参量发生放大器做激发源,利用激光诱导荧光光谱技术得到NO分子在200~370nm范围内的荧光光谱,谱线峰值归属于A^2∑(v’=1)→X^2∏(v”=1,3~11)跃迁,用最小二乘法拟合获得NO分子X^2∏态振动常数,计算出平衡位置的力常数k。通过测量NO分子在不同气压下A^2∑→X^2∏跃迁的时间分辨谱,得到A^2∑(v’=1)态的自然寿命为180ns。结果可为用激光诱导荧光光谱技术探测大气污染物NO分子提供理论及实验参考。 相似文献