Revealing the Three-Dimensional Orientation and Interplay between Plasmons and Interband Transitions for Single Gold Bipyramids by Photoluminescence Excitation Pattern Imaging

2021 ◽  
Author(s):  
Quan Liu ◽  
Dandan Ge ◽  
Frank Wackenhut ◽  
Caitlin D. Coplan ◽  
Charles Cherqui ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Photoluminescence Excitation ◽  
Interband Transitions ◽  
Excitation Pattern

scholarly journals Синтез и фотолюминесценция наноразмерных структур на основе сульфидов цинка, кадмия и марганца в полиакрилатной матрице

2020 ◽  
Vol 54 (12) ◽  
pp. 1321
Author(s):  
А.А. Исаева ◽  
В.П. Смагин
Keyword(s):  
Optical Radiation ◽  
Energy Levels ◽  
Radiation Energy ◽  
Photoluminescence Excitation ◽  
Photoluminescence Spectra ◽  
Interband Transitions ◽  
Nanoscale Structures ◽  
Semiconductor Structures ◽  
Recombination Processes ◽  
Zinc Cadmium

Photoluminescence of nanoscale structures based on zinc, cadmium and manganese sulfides depending on the conditions of synthesis and doping in the medium (poly)methylmethacrylate (PMMA). Photoluminescence excitation is associated with interband transitions of electrons in the semiconductor structures, absorption of optical radiation energy by defects in the crystal structure, as well as with the transfer of energy to the excited energy levels of Mn2+ ions. Luminescence occurs as a result of recombination processes at the levels of defects in the structure of the surface of particles and 4T1 → 6A1 transitions between the proper energy levels of Mn2+ ions. Based on changes in the photoluminescence spectra and photoluminescence excitation of PMMA/(Zn,Cd,Mn)S compositions, assumptions are made about the structure of particles. It is shown that their photoluminescence is affected by the distribution of Mn2+ ions in the structure of layers and on the surface of particles.

scholarly journals Collective modes in multi-Weyl semimetals

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Seongjin Ahn ◽  
E. H. Hwang ◽  
Hongki Min
Keyword(s):  
Three Dimensional ◽  
Critical Density ◽  
Collective Modes ◽  
Band Model ◽  
Interband Transitions ◽  
Linear Dispersion ◽  
Long Wavelength ◽  
Band Dispersion ◽  
Weyl Semimetals ◽  
Non Linear

Abstract We investigate collective modes in three dimensional (3D) gapless multi-Weyl semimetals with anisotropic energy band dispersions (i.e., "Equation missing" with a positive integer J). For comparison, we also consider the gapless semimetals with the isotropic band dispersions (i.e. E ~ k J ). We calculate analytically long-wavelength plasma frequencies incorporating interband transitions and chiral properties of carriers. For both the isotropic and anisotropic cases, we find that interband transitions and chirality lead to the depolarization shift of plasma frequencies. For the isotropic parabolic band dispersion the long-wavelength plasmons do not decay via Landau damping, while for the higher-order band dispersions the long-wavelength plasmons experience damping below a critical density. For systems with the anisotropic dispersion the density dependence of the long-wavelength plasma frequency along the direction of non-linear dispersion behaves like that of the isotropic linear band model, while along the direction of linear dispersion it behaves like that of the isotropic non-linear model. Plasmons along both directions remain undamped over a broad range of densities due to the chirality induced depolarization shift. Our results provide a comprehensive picture of how band dispersion and chirality affect plasmon behaviors in 3D gapless chiral systems with the arbitrary band dispersion.

scholarly journals Оптические свойства трехмерных островков InGaP(As), сформированных методом замещения элементов пятой группы

2021 ◽  
Vol 129 (2) ◽  
pp. 218
Author(s):  
Н.В. Крыжановская ◽  
А.С. Драгунова ◽  
С.Д. Комаров ◽  
А.М. Надточий ◽  
А.Г. Гладышев ◽  
...  
Keyword(s):  
Optical Properties ◽  
Carrier Transport ◽  
Room Temperature ◽  
Three Dimensional ◽  
Wavelength Shift ◽  
Nonradiative Recombination ◽  
Two Dimensional ◽  
Photoluminescence Excitation ◽  
Excitation Spectra ◽  
Recombination Centers

Photoluminescence spectroscopy (PL) has been used to study the optical properties of three-dimensional quantum-sized InGaPAs islands formed by substituting phosphorus by arsenic in an InGaP layer deposited on GaAs directly during epitaxial growth. PL line of the formed array of islands is in the range of 950–1000 nm at room temperature. Studies of PL in the temperature range 78–300 K indicate a significant inhomogeneity of the island array, the presence of nonradiative recombination centers, and carrier transport between islands. We observe in the photoluminescence excitation spectra a line associated with absorption in the residual two-dimensional InGaPAs layer. Annealing of the structures results in 300% increase of the PL intensity at room temperature with an insignificant short-wavelength shift of the island PL line, and also in improvement of the homogeneity within the island array.

scholarly journals Спектры пропускания квантовых ям и пленок на основе HgTe в дальнем ИК-диапазоне

2018 ◽  
Vol 60 (4) ◽  
pp. 774
Author(s):  
М.Л. Савченко ◽  
Н.Н. Васильев ◽  
А.С. Ярошевич ◽  
Д.А. Козлов ◽  
З.Д. Квон ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Surface States ◽  
Far Infrared ◽  
Infrared Range ◽  
Optical Transitions ◽  
Interband Transitions ◽  
New Class ◽  
Transmission And Reflection Spectra ◽  
Bulk Band ◽  
Transmission And Reflection

AbstractStrained 80-nm-thick HgTe films belong to a new class of materials referred to as three-dimensional topological insulators (i.e., they have a bulk band gap and spin-nondegenerate surface states). Though there are a number of studies devoted to analysis of the properties of surface states using both transport and magnetooptical techniques in the THz range, the information about direct optical transitions between bulk and surface bands in these systems has not been reported. This study is devoted to the analysis of transmission and reflection spectra of HgTe films of different thicknesses in the far-infrared range recorded in a wide temperature range in order to detect the above interband transitions. A peculiarity at 15 meV, which is sensitive to a change in the temperature, is observed in spectra of both types. Detailed analysis of the data obtained revealed that this feature is related to absorption by HgTe optical phonons, while the interband optical transitions are suppressed.

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

Structural organization of escherichia coli ribosomes as determined by immuno electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 166-167 ◽  
Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Spatial Arrangement ◽  
Small Subunit ◽  
Antibody Binding ◽  
Immuno Electron Microscopy

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).

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