共查询到15条相似文献,搜索用时 46 毫秒
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对交流电场下双巯基烷烃硫醇自组装分子膜的阻抗谱进行了研究.利用汞金属作为衬底,制备出双巯基烷烃硫醇自组装分子膜,并通过交流频谱仪对其进行频谱的扫描.明确了膜的作用范围为阻抗谱中频部分为了解释该阻抗谱,提出了一种串联的等效电路来进行了拟合,并与其他的模型进行比较.同时,观察到在损耗谱中损耗峰随硫醇碳链原子数的增加而向低频方向移动并得出双巯基硫醇(C6-C10)在交流电场下的激活能为23~39 meV. 相似文献
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利用扫描隧道显微镜诱导发光技术, 对有机分子α-6T在Ag(100)表面的自组装和光子发射特性进行了研究. 发现在极低的覆盖率下,α-6T分子以四个分子形成一种独特的风车形状的异构体. 随着覆盖率的增加,α-6T分子倾向于肩并肩紧密排列形成条纹状结构. 进一步增加覆盖率时,分子以低层分子的条纹结构作为模板,一层一层往上生长. 在五层分子厚度的样品上,利用光致方法可以获得分子荧光,这说明顶层分子已经被有效脱耦合. 然而在同样的样品上,STM诱导发光光谱却只展现出类似等离激元的发射特性. 在这种情况下,分子荧 相似文献
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本文使用含时量子主方程,从理论上计算了当分子或者等离激元分别被激发的情形下等离激元-分子耦合体系发光特性的时间和光谱演化,并在此基础上讨论了纳腔等离激元在扫描隧道显微镜(STM)诱导发光中发挥的不同作用.当STM针尖在分子上方,隧穿电子可以直接激发分子时,纳腔等离激元的主要作用是通过提高分子的辐射速率来增强其发光,此时耦合体系表现出具有分子特征的尖锐发光峰.另一方面,当STM针尖非常靠近分子边缘但没有载流子注入直接激发分子时,等离激元-分子之间的相干耦合会在这两个量子客体之间产生相消干涉,导致在分子激子能量附近出现法诺共振,使我们观察到具有法诺凹谷特征的等离激元发光光谱. 相似文献
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在Au(111)表面自组装制备了不同链长的烷烃硫醇分子膜,并利用导电原子力显微镜研究了 自组装分子膜的输运特性随外加压力的变化.结果发现分子膜的电流随压力的增加而增大, 其变化特征可以较好地用Hertz模型描述.在相同压力和电压下,通过分子膜的电流随分子链 长的增加呈指数衰减,其衰减因子先随压力的增加而减小,后逐渐趋于稳定.此外,长链分 子自组装膜的电流随压力的变化比短链分子膜更为明显.分析表明,自组装硫醇分子膜输运 特征的压力依赖性主要源于电荷在分子膜中的链间隧穿过程.
关键词:
分子自组装
输运特性
原子力显微镜 相似文献
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在金(111)表面组装了具有不同末端基团的硫醇单层分子膜,并利用导电原子力显微镜研究了分子膜的电输运性质,发现不同末端基团的分子自组装膜的导电能力有明显差别.结合X射线光电子能谱,研究了末端基团中碳原子的结合能与相应硫醇分子电导的关系.结果表明不同末端基团分子膜导电能力的差别可归结为末端基团碳原子电子结合能的差异.结合能越高,末端基团电子的局域化程度越强,导致电子有效注入分子主链的势垒越高,从而减弱了分子膜对电子的输运能力.此外,实验还发现不同末端基团的硫醇单层分子膜有不同的表面电势,导致分子膜电流电压特性曲线的零点产生偏离.
关键词:
分子自组装膜
输运特性
末端基团
导电原子力显微镜 相似文献
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Tunneling electrons-induced molecular fluorescence in organic film is enhanced by the surface plasmons. The plasmon enhancement can be expected not only by the plasmons of the substrate but also by the noble metal tip of scanning tunneling microscope (STM). In this report we investigate the tip effect in photoluminescence of meso-tetrakis(3,5-di-tertiarybutyl-phenyl)porphyrin (H2TBPP) film on indium tin oxide (ITO) combined with a STM. The experimental result shows the PL of molecules is enhanced by an Ag tip. This enhancement factor is evaluated larger than 2000. 相似文献
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本文利用扫描隧道显微镜诱导发光技术,系统地研究了铂酞菁分子在正负偏压激发下的电致发光行为及其相关的电子激发机制. 铂酞菁分子在正负偏压激发下均可以发光,但发光特征有所不同. 在负偏压激发下,观察到了源于中性PtPc分子LUMO→HOMO跃迁的峰位在637 nm处的荧光峰. 荧光强度在三个不同的激发区域呈阶梯状增加. 当激发偏压处于区域(I)时,可以产生较强的荧光,其主导激发机制是载流子注入激发机制;当激发偏压处于区域(II)时,可以产生中等发光强度的荧光,其主导激发机制是非弹性电子散射激发机制;当激发偏压处于区域(III)时,激发电子能量小于荧光光子能量,存在上转换现象,荧光峰非常弱,其激发过程需要自旋三重态作为中继态,并由载流子注入和非弹性电子散射两种机制共同作用产生. 在正偏压激发下,分子的电致发光光谱特征变得更加复杂,具有多个发光峰. 911 nm处的尖锐发光峰起源于PtPc-阴离子的LUMO+1→LUMO跃迁,其激发主要是由载流子注入激发机制主导. 相似文献
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The evolution of the surface structure in dodecanethiol self-assembled monolayer on Au(1 1 1) substrate has been studied with ultra high vacuum scanning tunneling microscopy at several temperatures. The structure of substrate Au(1 1 1) surface changed suddenly at a temperature of 110 °C. The enhanced mobility of the substrate gold atoms at this temperature is attributed to the desorption of the dodecanethiol molecules. 相似文献
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We investigated desorption of chlorine atoms on Si (1 1 1)-(7 × 7) surfaces induced by hole injection from scanning tunneling microscope tips. The hole-induced desorption of chlorine atoms had a threshold bias voltage corresponding to the energy position of the S3 surface band originated in Si backbonds. The chlorine atom desorption rate was almost proportional to the square of the tunneling current. We have discussed possible mechanisms that two holes injected into Si surface states get localized at the backbonds of chlorinated Si adatoms, which induces the rupture of Cl-Si bonds to result in chlorine atom desorption. 相似文献
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Injection of tunneling electrons and holes from the probe tips of a scanning tunneling microscope was found to enhance the hopping motion of Cl atoms between neighboring dangling-bond sites of Si dimers on Si(1 0 0)-(2 × 1) surfaces, featured by the rate of hopping linearly dependent on the injection current. The hopping rate formed peaks at sample biases of VS∼+1.25 and −0.85 V, which agree with the peaks in the local density of states spectrum measured by scanning tunneling spectroscopy. The Cl hopping was enhanced at Cl-adsorbed sites even remote from the injection point. The Cl hopping by hole injection was more efficiently enhanced by sweeping the tip along the Si dimer row than by tip-sweeping along the perpendicular direction. Such anisotropy, on the other hand, was insignificant in the electron injection case. All of these findings can be interpreted by the model that the holes injected primarily into a surface band originated from the dangling bonds of Si dimers propagate quite anisotropically along the surface, and become localized at Cl sites somehow to destabilize the Si-Cl bonds causing hopping of the Cl atoms. The electrons injected into a bulk band propagate in an isotropic manner and then get resonantly trapped at Si-Cl antibonding orbitals, resulting in bond destabilization and hopping of the Cl atoms. 相似文献