Probing Optical Transitions in Porous Silicon by Reflectance Spectroscopy in the Near Infrared, Visible and UV

1994 ◽  
Vol 358 ◽  
Author(s):  
W. Theiβ ◽  
R. Arens-Fischer ◽  
M. Arntzen ◽  
M.G. Berger ◽  
S. Frohnhoff ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Dielectric Function ◽  
Near Infrared ◽  
Solid Phase ◽  
Pore Wall ◽  
Reflectance Spectroscopy ◽  
Wall Material ◽  
Bulk Silicon ◽  
Band Structure Calculations ◽  
Structure Calculations

ABSTRACTReflectance spectroscopy has been used to obtain the dielectric function of the solid phase of porous silicon. The method is based on a fit of a parameterized dielectric function model to measured spectra. A crucial step in the procedure is the 'dielectric averaging' of the microscopic dielectric function of the pore wall material to the macroscopic effective dielectric function which governs the optical properties.Results are given for heavily and moderately p-doped samples of various porosities. For the latter large differences to bulk silicon have been found. The obtained dielectric functions are compared to the results of band structure calculations taken from literature.

Linearized Augmented Plane Wave Band Structure Calculations and Dielectric Function of Layered TlGaSe2

2008 ◽  
Vol 47 (10) ◽  
pp. 8182-8187 ◽  
Author(s):  
Guseyn Orudzhev ◽  
YongGu Shim ◽  
Kazuki Wakita ◽  
Nazim Mamedov ◽  
Sevindzh Jafarova ◽  
...  
Keyword(s):  
Band Structure ◽  
Plane Wave ◽  
Dielectric Function ◽  
Wave Band ◽  
Augmented Plane Wave ◽  
Band Structure Calculations ◽  
Linearized Augmented Plane Wave ◽  
Structure Calculations

Polygermyne: Germanium sheet polymers with efficient near-infrared luminescence

2001 ◽  
Vol 667 ◽  
Author(s):  
Günther Vogg ◽  
Martin S. Brandt ◽  
Lex J.-P. Meyer ◽  
Martin Stutzmann ◽  
Zoltán Hajnal ◽  
...  
Keyword(s):  
Near Infrared ◽  
Stokes Shift ◽  
Layered Crystal ◽  
Zintl Phase ◽  
Infrared Luminescence ◽  
Band Structure Calculations ◽  
Optical And Electronic Properties ◽  
Direct Band ◽  
Topotactic Transformation ◽  
Structure Calculations

ABSTRACTThe structural, optical and electronic properties of the Ge sheet polymer poylgermyne are summarized. Prepared via topotactic transformation of Zintl-phase CaGe2, (GeH)n forms a layered crystal in a tr6 stacking sequence with a distance of 5.65 Å between adjacent layers. The photoluminescence at 1.3 eV is excited nearly resonantly with a Stokes shift of 0.2 eV. Together with band structure calculations this shows that polygermyne has a direct band gap.

scholarly journals Infrared Optical Conductivity of Bulk Bi2Te2Se

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 553
Author(s):  
Elena S. Zhukova ◽  
Hongbin Zhang ◽  
Victor P. Martovitskiy ◽  
Yurii G. Selivanov ◽  
Boris P. Gorshunov ◽  
...  
Keyword(s):  
Optical Conductivity ◽  
Near Infrared ◽  
Three Dimensional ◽  
Frequency Increase ◽  
Band Structure Calculations ◽  
Infrared Measurements ◽  
Dirac Materials ◽  
Bulk Carriers ◽  
Structure Calculations ◽  
Complex Dispersion

Mid- and near-infrared measurements reveal that the optical conductivity of the three-dimensional topological insulator, Bi2Te2Se, is dominated by bulk carriers and shows a linear-in-frequency increase at 0.5 to 0.8 eV. This linearity might be interpreted as a signature of three-dimensional (bulk) Dirac bands; however, band-structure calculations show that transitions between bands with complex dispersion contribute instead to the inter-band optical conductivity at these frequencies and, hence, the observed linearity is accidental. These results warn against the oversimplified interpretations of optical-conductivity measurements in different Dirac materials.

scholarly journals Fermi surface of the skutterudite CoSb3 : Quantum oscillations and band-structure calculations

2021 ◽  
Vol 103 (8) ◽  
Author(s):  
M. Naumann ◽  
P. Mokhtari ◽  
Z. Medvecka ◽  
F. Arnold ◽  
M. Pillaca ◽  
...  
Keyword(s):  
Band Structure ◽  
Fermi Surface ◽  
Quantum Oscillations ◽  
Band Structure Calculations ◽  
Structure Calculations

scholarly journals Predicting quality, texture and chemical content of yam (Dioscorea alata L.) tubers using near infrared spectroscopy

2021 ◽  
pp. 096703352110075
Author(s):  
Adou Emmanuel Ehounou ◽  
Denis Cornet ◽  
Lucienne Desfontaines ◽  
Carine Marie-Magdeleine ◽  
Erick Maledon ◽  
...  
Keyword(s):  
High Throughput ◽  
Dry Matter ◽  
Near Infrared ◽  
Reflectance Spectroscopy ◽  
Infrared Reflectance ◽  
Quality Traits ◽  
Near Infrared Reflectance Spectroscopy ◽  
Near Infrared Reflectance ◽  
Infrared Reflectance Spectroscopy ◽  
Texture Attributes

Despite the importance of yam ( Dioscorea spp.) tuber quality traits, and more precisely texture attributes, high-throughput screening methods for varietal selection are still lacking. This study sets out to define the profile of good quality pounded yam and provide screening tools based on predictive models using near infrared reflectance spectroscopy. Seventy-four out of 216 studied samples proved to be moldable, i.e. suitable for pounded yam. While samples with low dry matter (<25%), high sugar (>4%) and high protein (>6%) contents, low hardness (<5 N), high springiness (>0.5) and high cohesiveness (>0.5) grouped mostly non-moldable genotypes, the opposite was not true. This outline definition of a desirable chemotype may allow breeders to choose screening thresholds to support their choice. Moreover, traditional near infrared reflectance spectroscopy quantitative prediction models provided good prediction for chemical aspects (R2 > 0.85 for dry matter, starch, protein and sugar content), but not for texture attributes (R2 < 0.58). Conversely, convolutional neural network classification models enabled good qualitative prediction for all texture parameters but hardness (i.e. an accuracy of 80, 95, 100 and 55%, respectively, for moldability, cohesiveness, springiness and hardness). This study demonstrated the usefulness of near infrared reflectance spectroscopy as a high-throughput way of phenotyping pounded yam quality. Altogether, these results allow for an efficient screening toolbox for quality traits in yams.

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