scholarly journals Carrier Mobility in Semiconductors at Very Low Temperatures

2021 ◽  
Vol 6 (1) ◽  
pp. 86
Author(s):  
Ingo Tobehn-Steinhäuser ◽  
Manfred Reiche ◽  
Matthias Schmelz ◽  
Ronny Stolz ◽  
Thomas Fröhlich ◽  
...  
Keyword(s):  
Carrier Concentration ◽  
Low Temperatures ◽  
Carrier Mobility ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Initial Concentration ◽  
Temperature Range ◽  
Type Silicon ◽  
Silicon Materials ◽  
Freeze Out

Carrier mobilities and concentrations were measured for different p- and n-type silicon materials in the temperature range 0.3–300 K. Simulations show that experimentally determined carrier mobilities are best described in this temperature range by Klaassen’s model. Freeze-out reduces the carrier concentration with decreasing temperature. Freeze-out, however, depends on the dopant type and initial concentration. Semi-classical calculations are useful only for temperatures above 100 K. Otherwise quantum mechanical calculations are required.

Measurement of the broadening of the sodium resonance lines by helium

1976 ◽  
Vol 54 (6) ◽  
pp. 619-625 ◽  
Author(s):  
G. H. Copley
Keyword(s):  
Absorption Coefficient ◽  
Low Temperatures ◽  
Laser Intensity ◽  
Scattered Light ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Line Profiles ◽  
Tunable Dye Laser ◽  
Collision Broadening ◽  
High And Low Temperatures

A nitrogen-pumped, tunable dye laser has been used to excite Na D-line fluorescence in a re-entrant scattering cell (maintained at 500 K) filled with He at pressures up to 300 Torr. The laser was scanned across the D lines, broadened in collisions with He atoms. The intensity of the resonantly scattered light was recorded at right angles to the laser beam since, in this direction, the absorption coefficient was independent of the laser intensity. D-line profiles obtained in this fashion were then analyzed to obtain collision-broadening coefficients. These coefficients of values 2.4 ± 0.3 and 2.8 ± 0.4 (in units of 10−9 rad s−1 cm3), for the D1 and D2 lines respectively, are compared with recent measurements at high and low temperatures and with several quantum mechanical calculations.

Carrier concentration model forn‐type silicon at low temperatures

1989 ◽  
Vol 66 (6) ◽  
pp. 2437-2441 ◽  
Author(s):  
Richard M. Dickstein ◽  
Stephen L. Titcomb ◽  
Richard L. Anderson
Keyword(s):  
Carrier Concentration ◽  
Low Temperatures ◽  
Type Silicon

scholarly journals Syntone Chemistry. Theoretical Study on the Formation of Cysteine, Aspartic Acid, Asparagine and Threonine

2020 ◽  
Vol 71 (7) ◽  
pp. 278-283
Author(s):  
Gheorghe Surpateanu ◽  
Ileana Denisa Nistor ◽  
Ana-Maria Georgescu ◽  
Neculai Catalin Lungu
Keyword(s):  
Amino Acids ◽  
Carbon Monoxide ◽  
Theoretical Model ◽  
Aspartic Acid ◽  
Low Temperatures ◽  
Theoretical Study ◽  
Chemical Reactivity ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Reaction With Water

In this paper is presented a theoretical study of chemical reactivity on the formation of four proteinogenic amino acids: cysteine, aspartic acid, asparagine and threonine. According to a theoretical model based on three syntons: methylene, nitrene and carbon monoxide at low temperatures, aziridinone would be formed first. This one, with methylene and carbon monoxide forms further the precursors intermediates of these four proteinogenic amino acids. Finally, the precursors in reaction with water, a key component of the primary atmosphere, lead to amino acids specified above. The study is mainly based on quantum mechanical calculations, B88-LYP DFT. Methylaziridonil, aziridonilacetyl and ethylaziridonil radicals should be formed at low temperature, which finally in reaction with water will form cysteine, aspartic acid, asparagine and threonine.

Features of radiothermoluminescence of polypropylene and ethylene propylenediene elastomer SKEPT-4044 compositions with nanoscale metal-containing fillers

2020 ◽  
pp. 66-73
Author(s):  
A.M. Magerramov ◽  
◽  
N.I. Kurbanova ◽  
M.N. Bayramov ◽  
N.A. Alimirzoyeva ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Molecular Mobility ◽  
Fe3o4 Nanoparticles ◽  
Low Temperatures ◽  
Frost Resistance ◽  
Relaxation Processes ◽  
Ethylene Propylene ◽  
Temperature Range ◽  
Β Relaxation

Using radiothermoluminescence (RTL), the molecular mobility features in the temperature range of 77-300 K were studied for the polypropylene (PP)/ethylene propylene diene elastomer SKEPT-4044 with NiO, Cu2O and Fe3O4 nanoparticles (NPs) based on ABS-acrylonitrile butadiene or SCS-divinyl styrene matrices. It has been shown that the introduction of nanofillers in PP significantly affects the nature and temperature of γ- and β-relaxation processes, while the region of manifestation of the β-process noticeably shifts to the region of low temperatures. Composites with Cu2O NPs have a higher β-transition temperature Tβ than composites with other NPs. It was found that PP/SKEPT-4044 composites with Cu2O NPs with a dispersion of 11-15 nm and acrylonitrile butadiene thermoplastics have optimal frost resistance compared to other compositions.

Crystal Forms of Semisynthetic Ergot Alkaloid Terguride

2002 ◽  
Vol 67 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Ladislav Cvak ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ergot Alkaloid ◽  
Simplified Model ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystal Forms ◽  
X Ray ◽  
Independent Molecules

Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.

Dynamic Viscosity of Compressed Water to 10 Kilobar and Steam to 1500°C

1969 ◽  
Vol 11 (2) ◽  
pp. 189-205 ◽  
Author(s):  
E. A. Bruges ◽  
M. R. Gibson
Keyword(s):  
Gaseous Phase ◽  
Dynamic Viscosity ◽  
Low Temperatures ◽  
Pressure Range ◽  
Low Pressure ◽  
Temperature Range ◽  
Inversion Temperature ◽  
Pressure Steam ◽  
Correlating Equations ◽  
First Time

Equations specifying the dynamic viscosity of compressed water and steam are presented. In the temperature range 0-100cC the location of the inversion locus (mu) is defined for the first time with some precision. The low pressure steam results are re-correlated and a higher inversion temperature is indicated than that previously accepted. From 100 to 600°C values of viscosity are derived up to 3·5 kilobar and between 600 and 1500°C up to 1 kilobar. All the original observations in the gaseous phase have been corrected to a consistent set of densities and deviation plots for all the new correlations are given. Although the equations give values within the tolerances of the International Skeleton Table it is clear that the range and tolerances of the latter could with some advantage be revised to give twice the existing temperature range and over 10 times the existing pressure range at low temperatures. A list of the observations used and their deviations from the correlating equations is available as a separate publication.

scholarly journals Restructured single parabolic band model for quick analysis in thermoelectricity

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Jianbo Zhu ◽  
Xuemei Zhang ◽  
Muchun Guo ◽  
Jingyu Li ◽  
Jinsuo Hu ◽  
...  
Keyword(s):  
Fermi Level ◽  
Carrier Concentration ◽  
Carrier Mobility ◽  
Optimization Design ◽  
State Of The Art ◽  
Band Model ◽  
Carrier Effective Mass ◽  
Intermediate Variables ◽  
Level Calculation ◽  
Spb Model

AbstractThe single parabolic band (SPB) model has been widely used to preliminarily elucidate inherent transport behaviors of thermoelectric (TE) materials, such as their band structure and electronic thermal conductivity, etc. However, in the SPB calculation, it is necessary to determine some intermediate variables, such as Fermi level or the complex Fermi-Dirac integrals. In this work, we establish a direct carrier-concentration-dependent restructured SPB model, which eliminates Fermi-Dirac integrals and Fermi level calculation and emerges stronger visibility and usability in experiments. We have verified the reliability of such restructured model with 490 groups of experimental data from state-of-the-art TE materials and the relative error is less than 2%. Moreover, carrier effective mass, intrinsic carrier mobility and optimal carrier concentration of these materials are systematically investigated. We believe that our work can provide more convenience and accuracy for thermoelectric data analysis as well as instructive understanding on future optimization design.

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