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Journal ArticleDOI

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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Journal ArticleDOI
TL;DR: In this article, three-dimensional porous graphene-like sheets (3DPGLS) were directly synthesized from biocarbons at 900 °C using Potassium carbonate as a catalyst to release graphite microcrystals from the crosslinked sp3 carbon atoms in the hard carbon phase and subsequently recrystallized them to form graphene layers.

181 citations

Journal ArticleDOI
TL;DR: Time-resolved transmissivity and reflectivity of exfoliated graphene and thin graphite films on a 295 K SiO(2)/Si substrate are measured and a fast recovery time constant and a longer one are identified, which attribute the temporal recovery to carrier cooling and recombination with the layer dependence related to substrate coupling.
Abstract: Time-resolved transmissivity and reflectivity of exfoliated graphene and thin graphite films on a 295 K SiO(2)/Si substrate are measured at 1300 nm following excitation by 150 fs, 800 nm pump pulses. From the extracted transient optical conductivity we identify a fast recovery time constant which increases from approximately 200 to 300 fs and a longer one which increases from 2.5 to 5 ps as the number of atomic layers increases from 1 to approximately 260. We attribute the temporal recovery to carrier cooling and recombination with the layer dependence related to substrate coupling. Results are compared with related measurements for epitaxial, multilayer graphene.

181 citations

Journal ArticleDOI
TL;DR: In this paper, the authors discuss Synthese, Charakterisierung, Struktur, and Eigenschaften of Graphen-Doppel-and -Mehrfachschichten.
Abstract: Alle paar Jahre werden neue Stoffklassen mit einzigartigen und faszinierenden Eigenschaften entdeckt. Beispiele aus der jungeren Vergangenheit sind Hochtemperatur-Supraleiter und Nanorohren aus Kohlenstoff. Die jungste dieser spektakularen Entdeckungen ist Graphen. Graphen weist ungewohnliche Eigenschaften wie einen halbzahligen Quanten-Hall-Effekt und eine ballistische Elektronenbewegung auf. Graphen ist ein zweidimensionaler Stoff und die Stammverbindung aller graphitischen Kohlenstoff-Formen. Graphen besteht in Reinform nur aus Monoschichten, es gibt aber auch betrachtliches Interesse an Graphen-Doppel- und -Mehrfachschichten. Die Synthese und Charakterisierung von Graphenen ist schwierig, in jungster Zeit sind hier aber grose Fortschritte erzielt worden. Wir berichten hier uber den aktuellen Stand der Graphenforschung einschlieslich Synthese, Charakterisierung, Struktur und Eigenschaften.

180 citations

Journal ArticleDOI
05 Jun 2012-ACS Nano
TL;DR: This work enhances the transfer efficiency of the large-area graphene films on a substrate with arbitrary thickness and rigidity and performs a theoretical multiscale simulation from continuum to atomic level to compare the mechanical stresses caused by the R2R and the hot-pressing methods.
Abstract: Graphene films grown on metal substrates by chemical vapor deposition (CVD) method have to be safely transferred onto desired substrates for further applications. Recently, a roll-to-roll (R2R) method has been developed for large-area transfer, which is particularly efficient for flexible target substrates. However, in the case of rigid substrates such as glass or wafers, the roll-based method is found to induce considerable mechanical damages on graphene films during the transfer process, resulting in the degradation of electrical property. Here we introduce an improved dry transfer technique based on a hot-pressing method that can minimize damage on graphene by neutralizing mechanical stress. Thus, we enhanced the transfer efficiency of the large-area graphene films on a substrate with arbitrary thickness and rigidity, evidenced by scanning electron microscope (SEM) and atomic force microscope (AFM) images, Raman spectra, and various electrical characterizations. We also performed a theoretical multisca...

180 citations


Cites background from "Raman spectrum of graphene and grap..."

  • ...Both the I2D/IG and the fwhm of the 2D band are consistent with those of monolayer graphene.(39) The low density of the D peaks suggests that the graphene film be well-transferred on the wafer without significant damages....

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Journal ArticleDOI
TL;DR: In this paper, an interface design strategy by matrix-alloying with Ti for in-situ interfacial carbide formation in reduced graphene oxide (RGO)/CuTi composites was reported.

180 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