Sensitivity gains in chemosensing by lasing action in organic polymers

Societal needs for greater security require dramatic improvements in the sensitivity of chemical and biological sensors. To meet this challenge, increasing emphasis in analytical science has been directed towards materials and devices having highly nonlinear characteristics; semiconducting organic polymers (SOPs), with their facile excited state (exciton) transport, are prime examples of amplifying materials. SOPs have also been recognized as promising lasing materials, although the susceptibility of these materials to optical damage has thus far limited applications. Here we report that attenuated lasing in optically pumped SOP thin films displays a sensitivity to vapours of explosives more than 30 times higher than is observed from spontaneous emission. Critical to this achievement was the development of a transducing polymer with high thin-film quantum yield, a high optical damage threshold in ambient atmosphere and a record low lasing threshold. Trace vapours of the explosives 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT) introduce non-radiative deactivation pathways that compete with stimulated emission. We demonstrate that the induced cessation of the lasing action, and associated sensitivity enhancement, is most pronounced when films are pumped at intensities near their lasing threshold. The combined gains from amplifying materials and lasing promise to deliver sensors that can detect explosives with unparalleled sensitivity.     

物质的芳香性

本文在论述了物质经典的芳香性理论的基础上，提出了一种非平面立体结构的物质的芳香性的判断方法。     

非线性光学材料

本文综述了非线性光学材料的研究状况,包括实用化器件的要求及材料的现状。     

蘑菇将取代塑料

人们一直在寻找塑料的替代者,科学家们相信,性能优异、环保无毒的真菌也许是最有希望取代塑料的材料。说起真菌,你的脑海里浮现出的可能是阴冷潮湿的下水道、长了毛的面包,想象力再好一点的同学可以想起小鸡炖蘑菇。事实上,真菌的价值远超一般人想象。只要条件适宜,这种生物能够在任何地方生长,形状不限,并且百分之百可降解,科学家也因此相信,有朝一日真菌能够取代塑料。     

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文章介绍了激光全息纸和激光全息膜材料的性能,分析了激光全息材料在全息技术上的应用,为激光全息材料在防伪印刷和包装印刷中的应用提供参考价值。     

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