单颗粒CVD金刚石的场发射

利用改造的扫描电子显微镜(SEM)设备，在SEM腔体中利用钨(W)探针测试了单颗粒金刚石的I-V与场发射特性，结果表明结晶良好的金刚石的I-V特性服从欧姆定律，而孤立的菜花状金刚石颗粒(cauliflower-like diamond)的I-V特性基本符合Pool-Frenkel输运特性.场发射特性表明，结晶良好的金刚石薄膜基本没有场发射，而孤立的菜花状的金刚石颗粒具有一定的场发射.CVD金刚石的场发射过程中，缺陷对电子的输运起主导作用.     

酶聚合体电流信号放大多通道电化学免疫传感体系及蛋白肿瘤标志物检测

本文构建了一种基于酶聚合体信号放大的多通道电化学免疫传感体系,并用于肝癌肿瘤标记物甲胎蛋白（AFP）的定量检测. 该传感体系由固定了抗AFP鼠单克隆抗体的多通道丝网印刷电极组成,可捕获肿瘤标记物抗原AFP,进而与抗AFP兔多抗特异性结合形成夹心免疫复合物,然后利用辣根过氧化物酶聚合体偶联的羊抗兔二抗（IgG-polyHRP）与三明治夹心免疫复合物结合,实现电流信号放大. 该体系结合多通道丝网印刷电极及自主研发的多通道电化学检测仪,可同时满足多通道电流信号的检测. 在最优化条件下,该传感体系检测AFP浓度的动态范围为64 pg·mL^-1 ~ 250 ng·mL^-1,最低检测下限为56 pg·mL^-1,具有检测灵敏度高、特异性强、操作简便以及仪器便携等优点.     

单根准直碳纳米纤维的场发射特性

采用等离子体增强热灯丝化学气相沉积方法，以甲烷和氢气为反应气体，在钨丝衬底上制备出准直的碳纳米纤维(CNFs)，其生长密度小于10.6cm-2，长度为6—30μm，直径为60—100nm.并采用自制的双探针扫描电子显微镜系统，对所生长的单根CNF作了场发射特性研究.结果表明，其场发射开启电压约为5V/μm，相应的发射电流达到20μA/cm2，同时，对不同长度的CNFs及单根CNF不同位置的场发射研究表明，场发射电流的大小不仅与材料本身的功函数、外电场场强、材料的微观结构以及宏观的几何结构有关，而且电子在输运过程中所受到的散射也是决定场发射电流大小的关键因素. 关键词： 碳纳米纤维 化学气相沉积 场发射 扫描电子显微镜     

Effects of N2 and glow discharge on growth behaviours of carbon nanotubes prepared by the hot filament chemical vapour deposition method

Carbon nanotubes (CNTs) are prepared by the hot filament chemical vapour deposition method using CH4 and H2 as reaction gases, and the growth behaviours are investigated by scanning electron microscopy and transmission electron microscopy. The results indicate that the CNTs prepared in the absence of N2 or glow discharge are bent; however, they are in an aligned state after introducing N2 into the chamber or forming glow discharge under a negative biased voltage. The results also indicate that the CNTs are of a bamboo-like structure when N2 is intruded as a reaction gas and the alignment degree of the CNTs grown under glow discharge is higher than that grown in N2. This illustrates that the nitric environment and glow discharge play important roles in the growth of CNTs. Combining with the theory related to alloy thermodynamics and collisions, we have analysed the growth mechanism of the CNTs in nitric environment and glow discharge.     

Transverse Writing of Multimode Interference Waveguides inside Silica Glass by Femtosecond Laser Pulses

Multi-mode interference waveguides are fabricated inside silica glass by transverse writing geometry with femtosecond laser pulses. The influences of several writing and reading factors on the output mode are systematically studied. The experimental results of straight waveguides are in good agreement with the simulations by the beam propagation method. By integrating a straight waveguide with a bent waveguide, a 1× 2 multi-mode splitter is formed and 2×3 lobes are observed in the output mode.