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A double-well resonant tunneling structure has been investigated carefully using the nonequilibrium Green's function method. We find that in the transmission probability two maxima appear even when the two levels have the same energy. This characteristic is at-tributed to the resonant tunneliug through mixed quasibound states. The tunneling current formula through this system under a dc voltage has been derived exactly. Three different cases are considered and several novel properties are found, which manifest coherent charac-teristics of the tunneling process. 相似文献
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以纳米中空介孔SiO2为壳,制备具有核壳结构的纳米介孔ZnO@SiO2催化剂,采用透射电子显微镜(TEM)、X射线衍射(XRD)和比表面积(BET)等进行表征,在酸性介质中测定其光催化活性.实验结果表明:纳米介孔ZnO@SiO2催化剂直径约为50 nm,颗粒均一,分散性较好;在pH大于3的酸性介质中能稳定存在并且保持催化活性;在亚甲基蓝(MB)浓度初始浓度为10 mg/L,催化剂用量5 mg,pH为5时,降解率达到98.6;,循环5次后,催化效率依然在61.5;.该催化剂具有较强的耐酸性能,在酸性染料废水处理中具有巨大的应用前景. 相似文献
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