分类： 材料科学 >> 材料科学（综合） 提交时间： 2020-08-12
Penglei Zhang
Peng Heng
Qingkai Yu
Gang Wang
Tao Huang
Siwei Yang
Xiaosong Liu
Zhi Liu
Xiaoming Xie
Guqiao Ding
摘要： Graphene has well demonstrated its unique properties and advantageous performances in lots of fields during the last 16 years. However, its industrial applications are still impeded by inefficient mass fabrication of high-quality graphene because of the great challenge in deep yet non-destructive graphite exfoliation. Herein, we demonstrated a delocalized electrochemical exfoliation (DEE) technique to efficiently fabricate high-quality graphene. Importantly, chemically transmitting the electric potentials was firstly proposed to spatially extend the exfoliation capability of electric potentials and electrochemically exfoliate every graphite particle dispersed in the electrolyte. The resulting graphene possesses ultralow defect density (ID/IG~0.07) and extremely high carbon-to-oxygen ratio (~28). Remarkably, high yields (~98.4%, 1-10 layers) and record high production rates (~72.7 g h?1) are realized in up-scaled batch of DEE. Further mechanism investigation revealed that the exfoliation capability of the electric potentials was transmitted to the whole electrolyte system by a dynamically favorable pathway. This pathway includes electrochemical oxidation, intercalation and interlayer bubble generation reactions, which makes deep and non-destructive exfoliation possible for every dispersed graphite particle in a scalable and reproducible manner. This way of using electric potentials differs from existing electrochemical methods and guarantees high throughput as well as high quality. The strategy of delocalized electrochemical exfoliation and the underlying concept of chemically transmitting the electric potentials would accelerate the commercialization of graphene and inspire more efficient fabrication of two-dimensional materials.
分类： 物理学 >> 核物理学 提交时间： 2016-09-14
摘要： It is noted that the low-energy behavior of the pion-photon transition form factor Fπγ(Q2) is sensitive to the transverse distribution of the pion wavefunction, and its high-energy behavior is sensitive to the longitudinal one. Thus a careful study on Fπγ(Q2) can provide helpful information on the pion wavefunction precisely. In this paper, we present a combined analysis of the data on Fπγ(Q2) reported by the CELLO, the CLEO, the BABAR and the BELLE collaborations. It is performed by using the method of least squares. By using the combined measurements of BELLE and CLEO Collaborations, the pion wavefunction longitudinal and transverse behavior can be fixed to a certain degree, i.e. we obtain β∈[0.691,0.757]GeV and B∈[0.00,0.235] for Pχ2≥90%, where β and B are two parameters of a convenient pion wavefunction model whose distribution amplitude can mimic the various longitudinal behavior under proper choice of parameters. We observe that the CELLO, CLEO and BELLE data are consistent with each other, all of which prefers the asymptotic-like distribution amplitude; while the BABAR data prefers a more broad distribution amplitude, such as the CZ-like one.
分类： 物理学 >> 核物理学 提交时间： 2016-09-14
摘要： In this article, we present the scalar-diquark-scalar-diquark-antiquark type and scalar-diquark-axialvector-diquark-antiquark type pentaquark configurations in the diquark model, and study the masses and pole residues of the JP=12± hidden-charmed pentaquark states in details with the QCD sum rules by extending our previous work on the JP=32− and 52+ hidden-charmed pentaquark states. We calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion by constructing both the scalar-diquark-scalar-diquark-antiquark type and scalar-diquark-axialvector-diquark-antiquark type interpolating currents. The present predictions of the masses can be confronted to the LHCb experimental data in the future.
分类： 物理学 >> 核物理学 提交时间： 2016-09-02
摘要： In this paper, we study the properties of the twist-3 distribution amplitude (DA) of the heavy pseudo-scalars such as ηc, Bc and ηb. New sum rules for the twist-3 DA moments ⟨ξnP⟩HP and ⟨ξnσ⟩HP up to sixth orders and up to dimension-six condensates are deduced under the framework of the background field theory. Based on the sum rules for the twist-3 DA moments, we construct a new model for the two twist-3 DAs of the heavy pseudo-scalar with the help of the Brodsky-Huang-Lepage prescription. Furthermore, we apply them to the Bc→ηc transition form factor (fBc→ηc+(q2)) within the light-cone sum rules approach, and the results are comparable with other approaches. It has been found that the twist-3 DAs ϕP3;ηc and ϕσ3;ηc are important for a reliable prediction of fBc→ηc+(q2). For example, at the maximum recoil region, we have fBc→ηc+(0)=0.674±0.066, in which those two twist-3 terms provide ∼33% and ∼22% contributions. Also we calculate the branching ratio of the semi-leptonic decay Bc→ηclν as Br(Bc→ηclν)=(9.31+2.27−2.01)×10−3.
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