不同参数多壁碳纳米管太赫兹谱特性

探索不同管径和长度的多壁碳纳米管(MWCNT)的太赫兹(THz)谱特性,采用透射型太赫兹时域光谱系统研究了5个不同管径和长度的MWCNT样品的太赫兹吸收谱和折射率谱,并对比和分析了它们的差异。结果表明:在0.2~2.0THz内,多壁碳纳米管太赫兹吸收没有特征吸收峰,吸收强度随着频率的增加而增加,并可以拟合为不同斜率的直线,且MWCNT在THz波段的吸收强度与管径和长度成正比。折射率随着频率的增加呈指数衰减,同时,管径是影响其折射率的一个重要因素,而长度对其影响不大。     

晶种分布对氧化锌纳米棒生长的影响

采用水热法在氧化锌晶种修饰的衬底上生长氧化锌纳米棒,利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)系统地分析了晶种分布状态对氧化锌纳米棒排列的影响.SEM结果表明随着晶种密度的增大,氧化锌纳米棒从排列无序向具有高度取向的紧密有序纳米棒阵列转变,反映纳米棒端面垂直生长优化;XRD表征显示,随着晶种密度的增大,(002)峰增强,(110)峰减弱,即端面衍射增强,侧面衍射减弱,与SEM结果相对应.同时在生长的氧化锌纳米棒中存在链状和花状的簇结构,分析表明这些簇结构与晶种在衬底上的特殊分布状态有关.     

Sniffing lung cancer related biomarkers using an oxidized graphene SAW sensor

Decane is one of the volatile organic compounds (VOCs) in human breath. Successful detection of decane in human breath has vast prospects for early lung cancer diagnosis. In this paper, a novel detecting device based on a filter surface acoustic wave (SAW) gas sensor is presented. SAW sensors coated with a thin oxidized graphene film were used to detect decane in parts per million (ppm) concentrations. Control and signal detection circuits were designed using a vector network analyzer with a detection resolution of insertion loss down to 0.0001 dB. The results showed that the SAW sensor could respond quickly with great sensitivity when exposed to 0.2 ppm decane. This device shows tremendous potential in medical diagnosis and environmental assessment.     

Quantum confinement effect in <Emphasis Type="Italic">β</Emphasis>-SiC nanowires

The quantum confinement effect is important in nanoelectronics and optoelectronics applications; however, there is a discrepancy between the theory of quantum confinement, which indicates that band-gap widening occurs only at small sizes, and experimental observations of band-gap widening in large-diameter nanowires (NWs). This paper reports an obvious blue shift of the absorption edge in the UV-visible absorption spectra of SiC NWs with diameters of 50–300 nm. On the basis of quantum confinement theory and high-resolution transmission electron microscopy images of SiC NWs, band-gap widening in SiC NWs with diameters of up to hundreds of nanometers is fully explained; the results could help to explain similar band-gap widening in other NWs with large diameters.