Raman spectrum of graphene and graphene layers.
TL;DR: This work shows that graphene's electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers, and allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area.
Abstract: Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality We show that its electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers The D peak second order changes in shape, width, and position for an increasing number of layers, reflecting the change in the electron bands via a double resonant Raman process The G peak slightly down-shifts This allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area
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TL;DR: The authors' data indicate that thermoelectric effects account for up to one-third of the contact temperature changes, and that current crowding accounts for most of the remainder, andModelling predicts that the role ofCurrent crowding will diminish and the roles of thermoeLECTric effects will increase as contacts improve.
Abstract: The temperatures of the graphene–metal contacts in working transistors have been measured with a resolution of ∼10 nm, revealing the presence of both heating and cooling effects.
320 citations
TL;DR: This work presents Hydrogen Sensing Using Pd-Functionalized Multi-Layer Graphene Nanoribbon Networks U N IC, a novel approach to chemical gas sensors based on nanoscale materials that has attracted research attention due to their naturally small size and large surface-to-volume ratio.
Abstract: www.MaterialsViews.com C O M M Hydrogen Sensing Using Pd-Functionalized Multi-Layer Graphene Nanoribbon Networks U N IC By Jason L. Johnson , Ashkan Behnam , S. J. Pearton , and Ant Ural * A IO N Sensing of gas molecules is critical in many fi elds including environmental monitoring, transportation, defense, space missions, energy, agriculture, and medicine. Solid state gas sensors have been developed for many of these applications. [ 1–3 ] More recently, chemical gas sensors based on nanoscale materials, such as carbon nanotubes and semiconductor nanowires, have attracted signifi cant research attention due to their naturally small size, large surface-to-volume ratio, low power consumption, room temperature operation, and simple fabrication. [ 4–6 ]
320 citations
TL;DR: The present work has discovered that the strong excitation wavelength dependent fluorescence in GO is originated from the "giant red-edge effect", which breaks Kasha's rule.
Abstract: The peak fluorescence emission of conventional fluorophores such as organic dyes and inorganic quantum dots is independent of the excitation wavelength. In contrast, the position of the peak fluorescence of graphene oxide (GO) in a polar solvent is heavily dependent on the excitation wavelength. The present work has discovered that the strong excitation wavelength dependent fluorescence in GO is originated from the “giant red-edge effect”, which breaks Kasha’s rule. When GO sheets are present in a polar solvent, the solvation dynamics slow down to the same time scale as the fluorescence due to the local environment of the GO sheet. Consequently, the fluorescence peak of GO broadens and red-shifts up to 200 nm with an increase in the excitation wavelength. The giant red-edge effect of GO disappears in a nonpolar solvent, leading to a narrow fluorescence peak that is independent of the excitation wavelength. Discovery of the underlying strong excitation wavelength dependent fluorescence mechanism provides g...
318 citations
Journal Article•
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TL;DR: In this paper, the potential of graphene as a material for fabricating various types of sensors is discussed, covering chemical and electrochemical sensors, magnetic and electric field sensors, optical sensors together with mass and strain sensors.
Abstract: This paper reviews the potential of graphene as a material for fabricating various types of sensors. Graphene is a monolayer of carbon atoms which exhibits some remarkable electronic and mechanical properties and many of these properties lend themselves to sensor applications. The review attempts to be comprehensive in sensor types covering chemical and electrochemical sensors, magnetic and electric field sensors, optical sensors together with mass and strain sensors. The fact that graphene offers some advantages over this entire range of sensing modalities is an indication of its versatility and importance.
318 citations
Cites background from "Raman spectrum of graphene and grap..."
...that both the 2D peak is sharper and has increased amplitude, while the peak is reduced for the single-layer flake [4]....
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TL;DR: The findings suggest that metal contacts can limit not only electrical transport but also thermal dissipation from submicrometer graphene devices.
Abstract: We report the thermal conductance G of Au/Ti/graphene/SiO2 interfaces (graphene layers 1 < n < 10) typical of graphene transistor contacts. We find G ~ 25 MW m-2 K-1 at room temperature, four times smaller than the thermal conductance of a Au/Ti/SiO2 interface, even when n = 1. We attribute this reduction to the thermal resistance of Au/Ti/graphene and graphene/SiO2 interfaces acting in series. The temperature dependence of G from 50 < T < 500 K also indicates that heat is predominantly carried by phonons through these interfaces. Our findings indicate that metal contacts can limit not only electrical transport, but also thermal dissipation from sub-micron graphene devices.
318 citations
References
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28 Jul 2005
TL;DR: PfPMP1）与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。
18,940 citations