140 research outputs found

    Non-contact method for measurement of the microwave conductivity of graphene

    Full text link
    We report a non-contact method for conductivity and sheet resistance measurements of graphene samples using a high Q microwave dielectric resonator perturbation technique, with the aim of fast and accurate measurement of microwave conductivity and sheet resistance of monolayer and few layers graphene samples. The dynamic range of the microwave conductivity measurements makes this technique sensitive to a wide variety of imperfections and impurities and can provide a rapid non-contacting characterisation method. Typically the graphene samples are supported on a low-loss dielectric substrate, such as quartz, sapphire or SiC. This substrate is suspended in the near-field region of a small high Q sapphire puck microwave resonator. The presence of the graphene perturbs both centre frequency and Q value of the microwave resonator. The measured data may be interpreted in terms of the real and imaginary components of the permittivity, and by calculation, the conductivity and sheet resistance of the graphene. The method has great sensitivity and dynamic range. Results are reported for graphene samples grown by three different methods: reduced graphene oxide (GO), chemical vapour deposition (CVD) and graphene grown epitaxially on SiC. The latter method produces much higher conductivity values than the others.Comment: 8 pages, 2 figures and 2 table

    Affine spherical homogeneous spaces with good quotient by a maximal unipotent subgroup

    Full text link
    For an affine spherical homogeneous space G/H of a connected semisimple algebraic group G, we consider the factorization morphism by the action on G/H of a maximal unipotent subgroup of G. We prove that this morphism is equidimensional if and only if the weight semigroup of G/H satisfies some simple condition.Comment: v2: title and abstract changed; v3: 16 pages, minor correction

    Terahertz radiation driven chiral edge currents in graphene

    Get PDF
    We observe photocurrents induced in single layer graphene samples by illumination of the graphene edges with circularly polarized terahertz radiation at normal incidence. The photocurrent flows along the sample edges and forms a vortex. Its winding direction reverses by switching the light helicity from left- to right-handed. We demonstrate that the photocurrent stems from the sample edges, which reduce the spatial symmetry and result in an asymmetric scattering of carriers driven by the radiation electric field. The developed theory is in a good agreement with the experiment. We show that the edge photocurrents can be applied for determination of the conductivity type and the momentum scattering time of the charge carriers in the graphene edge vicinity.Comment: 4 pages, 4 figure, additional Supplemental Material (3 pages, 1 figure

    Dream in a mode of biological rhythms of student's youth

    Full text link
    The healthy lifestyle of any person includes such important concepts as keeping of a mode of work and rest. For activity of a young organism importance of a dream represents special value. However in student's life as all of us know, it is very difficult to keep a constant sleep patternЗдоровый образ жизни любого человека включает такие немаловажные понятия как соблюдение режима труда и отдыха. Для жизнедеятельности молодого организма важность сна представляет особое значение. Однако, в студенческой жизни, как мы все знаем, очень трудно соблюдать постоянный режим сн

    ALBUMIN/THIACALIX[4]ARENE NANOPARTICLES AND THEIR SELF-ASSEMBLY WITH CIPROFLOXACIN

    Full text link
    The work was supported by Russian Science Foundation (№18-73-10094), https://rscf.ru/project/18-73-10094/

    DECASUBSTITUTED PILLAR[5]ARENE DERIVATIVES CONTAINING L-PHENYALANINE RESIDUES:SELF-ASSEMBLY AND INTERACTION WITH CYCLOSPORINE A

    Full text link
    The work was supported by Russian Science Foundation (№ 18-73-10094), https://rscf.ru/project/18-73-10094/

    AGGREGATION BEHAVIOR OF DECASUBSTITUTED PILLAR[5]ARENE DERIVATIVES CONTAINING GLYCINE AND L-ALANINE RESIDUES

    Full text link
    The work was supported by Russian Science Foundation (№ 18-73-10094), https://rscf.ru/project/18-73-10094/
    corecore