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We report on time-dependent density functional theory (TDDFT) calculations of the excited states of 63 different graphene quantum dots (GQDs) in square shape with side lengths 1 nm, 1.5 nm and 2 nm. We investigate the systematics and trends…
Optical properties of graphene are explored by using the generalized tight-binding model. The main features of spectral structures, the form, frequency, number and intensity, are greatly enriched by the complex relationship among the…
In recent years there has been significant debate on whether the edge type of graphene nanoflakes (GNF) or graphene quantum dots (GQD) are relevant for their electronic structure, thermal stability and optical properties. Using computer…
We demonstrate that optical transparency of any two-dimensional system with a symmetric electronic spectrum is governed by the fine structure constant and suggest a simple formula that relates a quasi-particle spectrum to an optical…
The combination of wide-band gap semiconductors like zinc oxide (ZnO) and graphene quantum dots (GQDs) is a promising strategy to tune optoelectronic properties of GQDs and to develop new functionalities. Here we report on a theoretical…
Graphene is a truly two-dimensional material with exceptional electronic, mechanical, and optical properties. As such, it consists of surface only and can be probed by the well developed surface-science techniques as, e.g., scanning…
Patterned graphene shows substantial potential for applications in future molecular-scale integrated electronics. Environmental effects are a critical issue in a single layer material where every atom is on the surface. Especially…
Despite the enormous interest in the properties of graphene and the potential of graphene nanostructures in electronic applications, the study of quantum confined states in atomically well-defined graphene nanostructures remains an…
We propose a 2D graphene structure containing atomic ensemble as a platform for implementing nanoscale enhanced coherent interactions of plasmonic fields with resonant atomic systems. We determine the graphene surface plasmon modes, and the…
The adsorption of fluorine, chlorine, bromine, and iodine diatomic molecules on graphene has been investigated using density functional theory with taking into account nonlocal correlation effects by means of vdW-DF approach. It is shown…
We present exemplary results of extensive studies of mechanical, electronic and transport properties of covalent functionalization of graphene monolayers (GML) with -NH2. We report new results of ab initio studies of covalent…
Graphene monolayer is a material with zero band gap, because of which its applications in optoelectronics are limited. The question arises, can we modify the optoelectronic properties of graphene by doping it with other atoms? Synthesis of…
We perform a comprehensive analysis of the spectrum of graphene plasmons which arise when a pair of sheets are confined between conducting materials. The associated enhanced local fields may be employed in the manipulation of light on the…
We develop the tight-binding model to study electronic and optical properties of graphane. The strong sp3 chemical bondings among the carbon and hydrogen atoms induce a special band structure and thus lead to the rich optical excitations.…
We present an alternative methodology for calculating the quasi-particle energy, energy loss, and optical spectra of a molecule deposited on graphene or a metallic substrate. To test the accuracy of the method it is first applied to the…
We employ scanning probe microscopy to reveal atomic structures and nanoscale morphology of graphene-based electronic devices (i.e. a graphene sheet supported by an insulating silicon dioxide substrate) for the first time. Atomic resolution…
We investigated Raman spectra of single-layer and multi-layer graphene under ultraviolet laser excitation at the wavelength of 325 nm. It was found that while the G peak of graphene remains pronounced in UV Raman spectra, the 2D band…
The electronic structure of few-layer graphene (FLG) samples with crystalline order was investigated experimentally by infrared absorption spectroscopy for photon energies ranging from 0.2 - 1 eV. Distinct optical conductivity spectra were…
Electronic, optical and transport properties of the graphene/ZnO heterostructure have been explored using first-principles density functional theory. The results show that Zn12O12 can open a band gap of 14.5 meV in graphene, increase its…
The electronic properties and optical excitations are investigated in the geometry- and field-modulated bilayer graphene systems, respectively, by using the tight-binding model and Kubo formula. The stacking symmetry of bilayer graphene can…