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仪器分析试验的正交设计 总被引:1,自引:0,他引:1
对一名分析化学工作者来说,在工作中经常遇到这样的问题,如用原子荧光光谱仪测定水或矿物中的铅时,发现灯电流、光电倍增管、负高压、载气(氩气)流量、观测高度和温度、硼氢化钾浓度、盐酸和铁氰化钾、草酸混合溶液浓度等都对测定灵敏度有影响,因此用最简单的方法,最少的检测次 相似文献
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马海峰 《Frontiers of Physics》2010,5(4):387-392
Functional nano-templates enable self-assembly of otherwise impossible arrangements of molecules. A particular class of such templates is that of sp 2 hybridized single layers of hexagonal boron nitride or carbon (graphene) on metal supports. If the substrate and the single layer have a lattice mismatch, superstructures are formed. On substrates like rhodium or ruthenium these superstructures have unit cells with ~3-nm lattice constant. They are corrugated and contain sub-units, which behave like traps for molecules or quantum dots, which are small enough to become operational at room temperature. For graphene on Rh(111) we emphasize a new structural element of small extra hills within the corrugation landscape. For the case of molecules like water it is shown that new phases assemble on such templates, and that they can be used as “nano-laboratories” where many individual processes are studied in parallel. Furthermore, it is shown that the h-BN/Rh(111) nanomesh displays a strong scanning tunneling microscopy-induced luminescence contrast within the 3 nm unit cell which is a way to address trapped molecules and/or quantum dots. 相似文献
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Hai-feng MA 《Frontiers of Physics》2010,5(4):387
Functional nano-templates enable self-assembly of otherwise impossible arrangements of molecules. A particular class of such templates is that of sp 2 hybridized single layers of hexagonal boron nitride or carbon (graphene) on metal supports. If the substrate and the single layer have a lattice mismatch, superstructures are formed. On substrates like rhodium or ruthenium these superstructures have unit cells with ~3-nm lattice constant. They are corrugated and contain sub-units, which behave like traps for molecules or quantum dots, which are small enough to become operational at room temperature. For graphene on Rh(111) we emphasize a new structural element of small extra hills within the corrugation landscape. For the case of molecules like water it is shown that new phases assemble on such templates, and that they can be used as “nano-laboratories” where many individual processes are studied in parallel. Furthermore, it is shown that the h -BN/Rh(111) nanomesh displays a strong scanning tunneling microscopy-induced luminescence contrast within the 3 nm unit cell which is a way to address trapped molecules and/or quantum dots. 相似文献
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We report the formation and local electronic
structure of Ge clusters on the Si(111)-7$\times $7 surface
studied by using variable temperature scanning tunnelling microscopy
(VT-STM) and low-temperature scanning tunnelling spectroscopy (STS).
Atom-resolved STM images reveal that the Ge atoms are prone to
forming clusters with 1.0~nm in diameter for coverage up to 0.12~ML.
Such Ge clusters preferentially nucleate at the centre of the
faulted-half unit cells, leading to the `dark sites'
of Si centre adatoms from the surrounding three unfaulted-half
unit cells in filled-state images.
Bias-dependent STM images show the charge transfer
from the neighbouring Si adatoms to Ge clusters.
Low-temperature STS of the Ge clusters reveals
that there is a band gap on the Ge cluster and the large voltage
threshold is about 0.9~V. 相似文献
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