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381.
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383.
Chunhua Liu Prof. Dr. Wei Zhang Prof. Dr. Qingdao Zeng Prof. Dr. Shengbin Lei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(20):6768-6773
By introducing an azobenzene group to the backbone of diboronic acid, we have obtained a surface‐confined, photoresponsive single‐layer covalent organic framework with long‐range order and almost entire surface coverage. Scanning tunneling microscopic characterization indicates that though the covalent linkage provides a significant locking effect, isomerization can still happen under UV irradiation, which causes destruction of the surface COF. Furthermore, the decomposed surface COF can recover upon annealing. This photoinduced decomposition provides a facile approach for the controlled capture and release of targeted objects using these nanoporous surface COFs as a host, which has been demonstrated in this work using copper phthalocyanine as a model guest. 相似文献
384.
采用真空热蒸发方法制备了有机单体薄膜对硝基苯腈p-nitrobenzonitrile(PNBN).利用扫描隧道显微镜(STM)在PNBN薄膜上进行信息记录点的写入,通过在STM针尖和高定向裂解石墨(HOPG)之间施加电压脉冲,直接观察到了信息记录点写入前后薄膜发生的局域结构转变.信息记录点的写入机制主要是这种纳米范围结构变化所导致的薄膜由高阻态向低阻态转变,高阻态对应0,低阻态对应1.
关键词:
p-nitrobenzonitrile(PNBN)
扫描隧道显微镜(STM)
结构转变 相似文献
385.
To modulate the tunneling gap with the lock-in amplifier in the scanning tunneling microscopy(STM), information of the tunneling current variation can be obtained. The local potential barrier distribution of graphite surface atoms is got by means of such technology. Compared with STM image under topography observation mode, the local potential barrier image has higher resolu tion and less influence on the tip and better anti-interference capability. Obs erved results of the graphite are given and discussed in this paper. 相似文献
386.
The growth of Pb films on the Si(1 0 0)-2 × 1 surface has been investigated at low temperature using scanning tunneling microscopy. Although the orientation of the substrate is (1 0 0), flat-top Pb islands with (1 1 1) surface can be observed. The island thickness is confined within four to nine atomic layers at low coverage. Among these islands, those with a thickness of six layers are most abundant. Quantum-well states in Pb(1 1 1) islands of different thickness are acquired by scanning tunneling spectroscopy. They are found to be identical to those taken on the Pb(1 1 1) islands grown on the Si(1 1 1)7 × 7 surface. Besides Pb(1 1 1) islands, two additional types of Pb islands are formed: rectangular flat-top Pb(1 0 0) islands and rectangular three-dimensional (3D) Pb islands, and both their orientations rotate by 90° from a terrace to the adjacent one. This phenomenon implies that the structures of Pb(1 0 0) and 3D islands are influenced by the Si(1 0 0)-2 × 1 substrate. 相似文献
387.
Xue Na Zhang Dimas G. de Oteyza Yutaka Wakayama Helmut Dosch 《Surface science》2009,603(21):3179-3183
We report a detailed study of the self-assembly process of di-indenoperylene (DIP) on Cu(1 0 0) surfaces, investigated by variable temperature scanning tunneling microscopy (STM) under ultrahigh vacuum (UHV) conditions. During the initial growth stages a preferred nucleation at the step edges is revealed. Subsequently, large ordered 2D islands grow from the step edges, while smaller 2D islands form on the terrace sites. The equilibrium fluctuation of these 2D clusters has been monitored in real-time, thereby obtaining a direct insight into the temperature dependence of the molecular surface diffusion. The substrate–adsorbate interactions determine the azimuthal molecular orientation, finally lead to the formation of highly ordered chiral domains which are commensurate with the substrate. 相似文献
388.
We report on the growth of ultrathin epitaxial Co films on Fe(1 1 0) examined by scanning tunneling microscopy and spectroscopy (STM and STS). At room temperature Co forms pseudomorphic, ideally ordered body-centered cubic (bcc) layers for the first two monolayers as confirmed by atomically resolved STM images. This is in contrast to the related case of Co/Cr(1 1 0) where a superstructure occurs in the second layer. The third monolayer forms a close-packed structure and causes a transformation of the buried second monolayer into a close-packed structure. The Fe(1 1 0) substrate strongly influences the electronic structure of the first Co monolayer as concluded from the dI/dU spectra. This influence is less important for the second monolayer. The measured local density-of-states function for the bcc Co double layer is in agreement with theoretical predictions for bcc Co. 相似文献
389.
Thin films of silicon nanoparticles (diameter 5-10 nm) were deposited on highly oriented pyrolytic graphite (HOPG) by low-pressure DC magnetron sputtering. The effect of different room-temperature oxidation techniques was investigated using XPS sputter-depth profiling. Both oxygen treatment during deposition (using an argon-oxygen mixture in the sputter gas) as well as post-deposition oxidation techniques (exposure to oxygen plasma beam, ambient air conditions) were studied. In all cases oxidation was found to involve the whole film down to the film/substrate interface, indicating a network of open pores. Depending on the type of oxidation between 15 and 25 at% of oxygen, mostly associated with low oxidation states of silicon, were detected in the interior of the film and attributed to oxidized surfaces of the individual silicon nanoparticles. The highest oxygen concentrations were found at the very film surface, reaching levels of 25-30% for films exposed to air or prepared by reactive magnetron sputtering. For the oxygen plasma-treated films even oxygen surface concentrations around 45% and fully oxidized silicon (i.e., SiO2) were achieved. At the Si/HOPG interface formation of silicon carbide was observed due to intermixing induced by Ar-ion beam used for sputter-depth profiling. 相似文献
390.
Continuing miniaturization of electronic devices necessarily requires assembly of several different objects or devices in
a small space. Therefore, besides thin films growth, the possibility of fabricating wires and dots [1, 2] at the nanometre
scale composed of metal silicides is of the top interest. This report is about the STM/STS investigation of cobalt silicides’
nanostructures created on Si(111)-(√19 × √19) substrates via Co evaporation and post deposition annealing. This (√19 × √19)
reconstruction was induced by Ni doping. Less than 1ML of Co on surface was obtained. Surface reconstruction induced growth
of agglomerates of clusters rather than an uniform layer. The post deposition annealing of a crystal sample (up to 670 K,
770 K, 870 K, 970 K, 1070 K and 1170 K) led to creation of silicides’ nanostructures. Measurements showed that coalescence
of Co nanoislands begun around 970 K. Annealing above 1070 K led to alloying of a Co, Ni and Si. As a consequence the Si(111)-(7×7)
reconstruction occurred at the cost of Si(111)-(√19 × √19).
相似文献