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: In this article, the authors measured carrier relaxation times in epitaxial graphene layers grown on SiC wafers and found that an initial fast relaxation transient in the 70-120 fs range is followed by a slower relaxation process in the 0.4-1.7 ps range.
Abstract: Using ultrafast optical pump-probe spectroscopy, we have measured carrier relaxation times in epitaxial graphene layers grown on SiC wafers. We find two distinct time scales associated with the relaxation of nonequilibrium photogenerated carriers. An initial fast relaxation transient in the 70-120 fs range is followed by a slower relaxation process in the 0.4-1.7 ps range. The slower relaxation time is found to be inversely proportional to the degree of crystalline disorder in the graphene layers as measured by Raman spectroscopy. We relate the measured fast and slow time constants to carrier-carrier and carrier-phonon intraband and interband scattering processes in graphene.
242 citations
TL;DR: This work has developed a simple and efficient approach for the synthesis of chemically converted graphene sheets via aryne cycloaddition under mild reaction conditions that can be well dispersed in various solvents.
241 citations
TL;DR: A simple method is reported for the visualization of arbitrarily large graphene domains by imaging the birefringence of a graphene surface covered with nematic liquid crystals to determine the boundaries of macroscopic domains.
Abstract: The boundaries between domains in single-layer graphene strongly influence its electronic properties. However, existing approaches for domain visualization, which are based on microscopy and spectroscopy, are only effective for domains that are less than a few micrometres in size. Here, we report a simple method for the visualization of arbitrarily large graphene domains by imaging the birefringence of a graphene surface covered with nematic liquid crystals. The method relies on a correspondence between the orientation of the liquid crystals and that of the underlying graphene, which we use to determine the boundaries of macroscopic domains.
241 citations
TL;DR: A molecular-scale active graphdiyne-based electrochemical actuator with a high electro-mechanical transduction efficiency of up to 6.03%, exceeding that of the best-known piezoelectric ceramic, shape memory alloy and electroactive polymer reported before, and its energy density is comparable to that of mammalian skeletal muscle.
Abstract: Electrochemical actuators directly converting electrical energy to mechanical energy are critically important for artificial intelligence. However, their energy transduction efficiency is always lower than 1.0% because electrode materials lack active units in microstructure, and their assembly systems can hardly express the intrinsic properties. Here, we report a molecular-scale active graphdiyne-based electrochemical actuator with a high electro-mechanical transduction efficiency of up to 6.03%, exceeding that of the best-known piezoelectric ceramic, shape memory alloy and electroactive polymer reported before, and its energy density (11.5 kJ m−3) is comparable to that of mammalian skeletal muscle (~8 kJ m−3). Meanwhile, the actuator remains responsive at frequencies from 0.1 to 30 Hz with excellent cycling stability over 100,000 cycles. Furthermore, we verify the alkene–alkyne complex transition effect responsible for the high performance through in situ sum frequency generation spectroscopy. This discovery sheds light on our understanding of actuation mechanisms and will accelerate development of smart actuators. Transduction efficiency in electrochemical actuators hardly exceeds 1% because the current electrode materials do not allow to efficiently exploit microstructural changes to achieve large actuation effects. Here the authors demonstrate transduction efficiencies up to 6% in actuators by using graphdiyne as electrode material.
240 citations
TL;DR: A graphene sheet using inkjet printing and a wideband dipole antenna application are provided to minimize the loss of raw material and time.
Abstract: PURPOSE: A graphene sheet using inkjet printing and a wideband dipole antenna application are provided to minimize the loss of raw material and time. CONSTITUTION: Waterborne graphene oxide nano particle solution is manufactured and is used for conductive ink of inkjet printing. The chemical characteristic of the waterborne graphene oxide nano particle solution is changed in order to form a detailed pattern on a supporting material. The waterborne graphene oxide nano particle solution is injected to a printer head, and an oxide graphene thin film is formed. The supporting material including the oxide graphene thin film is located in a vapor deposition reactor, and an oxidation-reduction reaction is executed. A graphene sheet based broadband dipole antenna electrode is connected to an antenna analysis device, and the performance of the antenna is measured.
240 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