scholarly journals Fine structure and optical properties of biological polarizers in crustaceans and cephalopods

2008 ◽  
Author(s):  
Tsyr-Huei Chiou ◽  
Roy L. Caldwell ◽  
Roger T. Hanlon ◽  
Thomas W. Cronin
Keyword(s):  
Optical Properties ◽  
Fine Structure

Symmetry Breaking Induced Activation of Nanocrystal Optical Transitions

MRS Advances ◽  
2018 ◽  
Vol 3 (14) ◽  
pp. 711-716 ◽  
Author(s):  
Peter C. Sercel ◽  
Andrew Shabaev ◽  
Alexander L. Efros
Keyword(s):  
Optical Properties ◽  
Fine Structure ◽  
Symmetry Breaking ◽  
Semiconductor Nanocrystals ◽  
Radiative Lifetime ◽  
Multipole Expansion ◽  
Cdse Nanocrystals ◽  
Coulomb Center ◽  
Charged Center ◽  
Positively Charged

ABSTRACTWe have analysed the effect of symmetry breaking on the optical properties of semiconductor nanocrystals due to doping by charged impurities. Using doped CdSe nanocrystals as an example, we show the effects of a Coulomb center on the exciton fine-structure and optical selection rules using symmetry theory and then quantify the effect of symmetry breaking on the exciton fine structure, modelling the charged center using a multipole expansion. The model shows that the presence of a Coulomb center breaks the nanocrystal symmetry and affects its optical properties through mixing and shifting of the hole spin and parity sublevels. This symmetry breaking, particularly for positively charged centers, shortens the radiative lifetime of CdSe nanocrystals even at room temperature, in qualitative agreement with the increase in PL efficiency observed in CdSe nanocrystals doped with positive Ag charge centers [A. Sahu et.al., Nano Lett. 12, 2587, (2012)]. The effect of the charged center on the photoluminescence and the absorption spectra is shown, with and without the presence of compensating charges on the nanocrystal surface. While spectra of individual nanocrystals are expected to shift and broaden with the introduction of a charged center, configuration averaging and inhomogeneous broadening are shown to wash out these effects. The presence of compensating charges at the NC surface also serves to stabilize the band edge transition energies relative to NCs with no charge centers.

The Fine Structure of the Scales and Teeth of Raia Clavata

1956 ◽  
Vol s3-97 (37) ◽  
pp. 99-107
Author(s):  
D. F. G. POOLE
Keyword(s):  
Optical Properties ◽  
Fine Structure ◽  
Crystallite Size ◽  
Organic Content ◽  
Collagen Fibres ◽  
X Ray ◽  
Polarizing Microscope ◽  
Mammalian Teeth

The fine structure of the scales of Raia clavata has been determined by means of the polarizing microscope and X-ray analysis. Each scale consists of a cone of dentine covered by an enamel-like layer and both of these tissues contain crystallites of the mineral hydroxyapatite. In each case the crystallite size is similar to that of mammalian dentine possessing the same mineral. However, whereas the dentine of Raia contains both collagen fibres and mineral crystallites arranged parallel with the surface of the scale, the enamel-like layer has a low organic content and its crystallites lie with their optic axes at right angles to the surface. These differences in crystallite arrangement and organic content result in different optical properties in the two tissues. Nevertheless, both tissues are produced by the mesoderm cells of the dentine papilla, and in this respect the enamel-like tissue differs fundamentally from the ectodermal enamel of mammalian teeth.

Optical Properties and X-ray Absorption Fine Structure Analysis of ZnS:Cu,Cl Thin-Film Phosphors

2010 ◽  
Vol 49 (8) ◽  
pp. 082602 ◽  
Author(s):  
Kunio Ichino ◽  
Haruki Kato ◽  
Yuichiro Sakai ◽  
Koutoku Ohmi ◽  
Tetsuo Honma ◽  
...  
Keyword(s):  
Thin Film ◽  
Optical Properties ◽  
Fine Structure ◽  
Structure Analysis ◽  
X Ray ◽  
Absorption Fine ◽  
Fine Structure Analysis ◽  
X Ray Absorption

Investigation of Oxygen Contamination in Indium Nitride Thin Film by X-Ray Absorption Fine Structure

2010 ◽  
Vol 93-94 ◽  
pp. 493-496
Author(s):  
K. Amnuyswat ◽  
Pitiporn Thanomngam ◽  
Suwat Sopitpan ◽  
A. Sungthong ◽  
Supanit Porntheeraphat ◽  
...  
Keyword(s):  
Optical Properties ◽  
Fine Structure ◽  
Local Structure ◽  
Indium Nitride ◽  
Indium Atom ◽  
Typical Structure ◽  
First Principle Calculation ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Local structures of indium oxynitride (InON) nano-crystal prepared by reactive gas-timing RF magnetron sputtering technique are under investigation. Since the optical properties of these InON thin films depend on gas-timing ratio, the local structure analysis is needed in order to determine the relation between the gas timing ratio and its optical properties. In this work, InON thinfilm with 30:0 seconds (N2:O2) gas-timings ratio was analyzed for its local structure using X-ray absorption fine structure (XAFS) technique in conjunction with first principle calculation. The results indicate that the crystal structure of the film is wurtzite structure which is a typical structure of InN. However from the results of Auger Electron Spectroscopy (AES), there are oxygen contents in the film. Since XAFS analysis confirmed the 4-fold local structure of Indium atom, these oxygen atoms must be substituted in nitrogen sites with slightly changing the local structure of Indium atom. The best fit of XAFS data indicated that there is an oxygen atom substituted in nitrogen site of the 4-fold indium.

scholarly journals Theoretical Study of Excitonic Complexes in GaAs/AlGaAs Quantum Dots Grown by Filling of Nanoholes

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Mohamed Omri ◽  
Amor Sayari ◽  
Larbi Sfaxi
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Fine Structure ◽  
Theoretical Study ◽  
Three Dimensional ◽  
Correlation Effect ◽  
Wave Functions ◽  
Transition Energies ◽  
New Family ◽  
Effective Mass Schrödinger Equation

In this work, a theoretical study of the electronic and the optical properties of a new family of strain-free GaAs/AlGaAs quantum dots (QDs) obtained by AlGaAs nanohole filling is presented. The considered model consists of solving the three-dimensional effective-mass Schrödinger equation, thus providing a complete description of the neutral and charged complex excitons’ fine structure. The QD size effect on carrier confinement energies, wave functions, and s-p splitting is studied. The direct Coulomb interaction impact on the calculated s and p states’ transition energies is investigated. The behaviour of the binding energy of neutral and charged excitons (X− and X+) and biexciton XX versus QD height is studied. The addition of the correlation effect allows to explain the nature of biexcitons often observed experimentally.

scholarly journals The fine structure of phloem fibres I. Untreated and swollen hemp

1940 ◽  
Vol 128 (851) ◽  
pp. 214-231 ◽  
Keyword(s):  
Optical Properties ◽  
Fine Structure ◽  
Natural Condition ◽  
Anatomical Study ◽  
Longitudinal Axis ◽  
Cellulose Chain ◽  
X Ray ◽  
Different Types

During an anatomical study of the jute and hemp plants carried out by one of us (B. C. K.), the opportunity was taken of reinvestigating in these plants the structure of the walls of the fibres, using the term “fibre” in its botanical sense. The so-called “bast” fibres are of particular interest in wall studies since it was apparently on the basis of their investigation that the “crossed fibrillar” conception was first introduction. Thus we find Reimers (1922) stating that in a number of plants, including hemp, the walls of these fibres are composed of two or more layers differing considerably in cellulose-Chain direction. Since that time numerous other statement of this kind have been made for different types of cell (Freudenberg and Dürr 1932; Ritter 1930; Ritter and Chidester 1928; Bailey and Kerr 1935); v. Iterson 1937; Wuhrmann-Meyer 1939). It seems rather a common feature of the evidence quoted in support of such a structure that it is derived from material swollen considerably either in acid or alkali. Certainly the optical properties of the wall have been used in support (Freudenberg and Durr 1932; Bailey and Kerr 1935 v. Iterson 1937; Wuhrmann-Meyer 1939). It seems rather a common feature of the evidence quoted in support of such a structure that it is derived from material swollen considerably either in acid or alkali. Certainly the optical properties of the wall have been used in support (Freudenberg and Durr 1932; Bailey and Kerr 1935 v. Iterson 1937; Wuhrmann-Meyer 1939). It seems rather a common feature of the evidence quoted in support of such a structure that it is derived from material swollen considerably either in acid or alkali. Certainly the optical properties of the wall have been used in support (Freudenberg and Durr 1932; Bailey and Kerr 1935; v. Iterson 1937; Wuhrmann-Meyer 1939). It seems rather a common feature of the evidence quoted in support of such a structure that it is derived from material swollen considerably either in acid or alkali. Certainly the optical properties of the wall have been used in support (Freudenberg and Dürr 1932; Bailey and Kerr 1935) but the implication of such work have already been discussed elsewhere (Preston 1939 a ). We are here concerned chiefly with the swelling technique. While it is not to be suggested that treatment with swelling reagents totally invalidates all observations of this type, it is quite clear that in some cases at least observation of swollen material can give an entirely erroneous conception of the wall in its natural condition. This is perhaps particularly clear in the case of jute, for which Osborne (1935, quoted also by Barker 1938) refers to the fibres as being composed of a series of chains lying at a considerable angle to the longitudinal axis of the cell, in spite of contrary X-ray evidence.

scholarly journals A Comparison between the Face of the Veil of Manoppello and the Face of the Shroud of Turin

Heritage ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 339-355 ◽  
Author(s):  
Liberato De Caro ◽  
Emilio Matricciani ◽  
Giulio Fanti
Keyword(s):  
Optical Properties ◽  
Fine Structure ◽  
Jesus Christ ◽  
Background Noise ◽  
Digital Processing ◽  
Logarithmic Transformation ◽  
The Face ◽  
Historical Relationship ◽  
Shroud Of Turin ◽  
The Veil

Recently we have studied the unusual optical properties of the Veil of Manoppello, a canvas representing the face of Jesus Christ, and restored digitally the face, by eliminating the distortions of the anatomic details due the yielding of the very fine structure of the fabric. The aim of the present paper is to compare the restored face of the Veil with that visible on the Turin Shroud. In particular, the paper focuses on assessing whether the two images can be superimposed, i.e., whether they are different images of the same face. Indeed, some scholars have suggested that the Veil of Manoppello and the Turin Shroud show different images of the same face. We demonstrate that the face of the Turin Shroud, after a logarithmic transformation of the intensity and the correction of the background noise, shows cheeks’ profiles, not visible before the digital processing, which overlap very well with those of the restored face of the Veil of Manoppello. These correlations between the two images of the face of Jesus raise the question of their historical relationship.

scholarly journals Real-time Characterization of the Optical Properties of an ultra-thin Surface Reaction Layer during Growth

1996 ◽  
Vol 441 ◽  
Author(s):  
N. Dietz ◽  
N. Sukidib ◽  
C. Harrisb ◽  
K. J. Bachmann
Keyword(s):  
Optical Properties ◽  
Fine Structure ◽  
Reaction Layer ◽  
Surface Reaction ◽  
Turning Points ◽  
Growth Conditions ◽  
Chemical Beam Epitaxy ◽  
Modulated Phase ◽  
Interference Oscillations

AbstractThe average optical properties of an ultra-thin surface reaction layer (SRL) during growth by pulsed chemical beam epitaxy (PCBE) can be quantitatively accessed by p-polarized reflectance spectroscopy (PRS), as demonstrated on the example of heteroepitaxial GaP growth. Under PCBE growth conditions, the surface of the substrate is exposed to pulsed ballistic beams of tertiarybutyl phosphine [TBP, (C4H9)PH2] and triethylgallium [TEG, Ga(C2H5)3]. The pulsed precursor supply causes a period in composition and thickness modulated SRL, monitored as a fine structure that is superimposed on interference oscillations, resulting from back reflection at the substratelayer interface with increasing layer thickness. The amplitude of this fine structure undergoes a period amplitude modulation and exhibits turning points at which the response to the first precursor pulse changes sign. The turning points can be characterized by the expression R4(Φmax)=R4(Φmin), which describes the maximal and minimal values of the temporally modulated phase factor in the SRL, using a four layer stack description. The positions of these turning points are not affected by the thickness of the SRL, which allows the computation of the average complex dielectric function of the SRL independent of its thickness. In the next step, the average thickness of the SRL can be extracted from the amplitude of the observed fine structure.

Fine structure and optical properties of an ostracode (Crustacea) nauplius eye

PROTOPLASMA ◽  
1981 ◽  
Vol 107 (3-4) ◽  
pp. 361-374 ◽  
Author(s):  
A. Andersson ◽  
D. -E. Nilsson
Keyword(s):  
Optical Properties ◽  
Fine Structure

Optical Properties and Local Structure of Cu(II) Dopant in ZnSe Nanoparticles

2003 ◽  
Vol 776 ◽  
Author(s):  
Thaddeus J. Norman ◽  
Donny Magana ◽  
Frank Bridges ◽  
Jin Z. Zhang
Keyword(s):  
Optical Properties ◽  
Fine Structure ◽  
Local Structure ◽  
Tetrahedral Site ◽  
Molecular Cluster ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Znse Nanoparticles ◽  
X Ray ◽  
X Ray Absorption

AbstractCu(II) doped ZnSe nanoparticles were synthesized using molecular cluster precursors. The Cu(II) dopant had the effect of quenching the ZnSe band edge emission, yet only weak emission from Cu(II) centers was observed. An X-ray Absorption Fine Structure (XAFS) experiment was performed on the Cu(II) doped ZnSe nanoparticles. It was determined that the Cu(II) occupies a tetrahedral site in the lattice in an environment similar to that of Cu in bulk Cu2Se, and is likely to have substituted for Zn(II) in the lattice.

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