Auger Ionization of Silicon Nanocrystals

1996 ◽  
Vol 452 ◽  
Author(s):  
B. Averboukh ◽  
D. Kovalev ◽  
M. Ben Chorin ◽  
F. Koch ◽  
Al.L. Efros ◽  
...  
Keyword(s):  
Low Temperature ◽  
Silicon Nanocrystals ◽  
Room Temperature ◽  
Polarized Light ◽  
Optical Excitation ◽  
Porous Si ◽  
Auger Process ◽  
Linearly Polarized

AbstractPhotoluminescence saturation under intense CW optical excitation and optical degradation of photoluminescence from porous Si are studied. The anisotropy of the luminescence is observed under intense linearly polarized illumination at room temperature and after polarized light induced degradation at low temperature. The Auger process is shown to be responsible for these observations.

scholarly journals Exciton-to-trion conversion as a control mechanism for valley polarization in room-temperature monolayer WS2

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Joris J. Carmiggelt ◽  
Michael Borst ◽  
Toeno van der Sar
Keyword(s):  
Room Temperature ◽  
Polarized Light ◽  
Optical Excitation ◽  
Equation Model ◽  
Chemical Doping ◽  
Transition Metal Dichalcogenide ◽  
Net Charge ◽  
Circularly Polarized Light ◽  
Valley Polarization

Abstract Transition metal dichalcogenide (TMD) monolayers are two-dimensional semiconductors with two valleys in their band structure that can be selectively addressed using circularly polarized light. Their photoluminescence spectrum is characterized by neutral and charged excitons (trions) that form a chemical equilibrium governed by the net charge density. Here, we use chemical doping to drive the conversion of excitons into trions in $$\text {WS}_{2}$$ WS 2 monolayers at room temperature, and study the resulting valley polarization via photoluminescence measurements under valley-selective optical excitation. We show that the doping causes the emission to become dominated by trions with a strong valley polarization associated with rapid non-radiative recombination. Simultaneously, the doping results in strongly quenched but highly valley-polarized exciton emission due to the enhanced conversion into trions. A rate equation model explains the observed valley polarization in terms of the doping-controlled exciton-trion equilibrium. Our results shed light on the important role of exciton-trion conversion on valley polarization in monolayer TMDs.

Crystallization in Unstretched Rubber. Microscopic Study in Polarized Light

1951 ◽  
Vol 24 (3) ◽  
pp. 550-556
Author(s):  
H. N. Campbell ◽  
M. D. Allen
Keyword(s):  
Low Temperature ◽  
Physical Properties ◽  
Melting Temperature ◽  
Microscopic Study ◽  
Room Temperature ◽  
Polarized Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Limited Mobility ◽  
Sensitive Method

Abstract Since many elastomers indicate by their physical properties that crystallization occurs even when such crystallization is not detectable by x-ray diffraction, a direct microscopic study in polarized light was undertaken. This study confirms the presence of such crystallinity not only in rubber but also in polybutadiene and some low-temperature copolymers. Furthermore, the same crystal pattern is reproduced on melting and refreezing provided the intermediate melting temperature is not too high. This indicates that x-ray diffraction is not a very sensitive method for detecting small amounts of crystallinity in high polymers. The reproduction of the crystal pattern on refreezing shows that the molecular segments have limited mobility even at room temperature; this may require revision of current theories of the origin of retractive forces in elastomers.

Anisotropy of the Porous Silicon Photoluminescence

1996 ◽  
Vol 452 ◽  
Author(s):  
G. Polisski ◽  
B. Averboukh ◽  
D. Kovalev ◽  
F. Koch
Keyword(s):  
Porous Silicon ◽  
Memory Effect ◽  
Linear Polarization ◽  
Polarized Light ◽  
Optical Excitation ◽  
Polarization Degree ◽  
Porous Si ◽  
Si Substrate ◽  
Plane Distribution

AbstractPolarization memory effect in the porous Si photoluminescence is studied. The anisotropy of the linear polarization degree is found in the samples etched with polarized light-assistance. The effect is explained by the anisotropie in plane distribution of the elongated Si crystallites. Under resonant optical excitation four-fold anisotropy of the photoluminescence polarization, linked to the crystalline axes of the bulk Si substrate, is observed.

scholarly journals Direct optical excitation of dark plasmons for hot electron generation

2019 ◽  
Vol 214 ◽  
pp. 159-173 ◽  
Author(s):  
Niclas S. Mueller ◽  
Bruno G. M. Vieira ◽  
Dominik Höing ◽  
Florian Schulz ◽  
Eduardo B. Barros ◽  
...  
Keyword(s):  
Polarized Light ◽  
Optical Excitation ◽  
Cost Effective ◽  
Hot Electrons ◽  
Hot Electron ◽  
Electron Generation ◽  
Linearly Polarized

We demonstrate the excitation of dark modes and creation of hot electrons using linearly polarized light and scalable, cost-effective plasmonic surfaces.

Survival of mouse blastocysts after low-temperature preservation under high pressure

2004 ◽  
Vol 52 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Cs. Pribenszky ◽  
M. Molnár ◽  
S. Cseh ◽  
L. Solti
Keyword(s):  
Phase Transition ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
High Hydrostatic Pressure ◽  
Room Temperature ◽  
Freezing Point ◽  
Significant Loss ◽  
Embryo Cryopreservation ◽  
Subzero Temperatures ◽  
Survival Capacity

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

Photophysical properties of N719 and Z907 dyes, benchmark sensitizers for dye-sensitized solar cells, at room and low temperature

2021 ◽  
Vol 23 (10) ◽  
pp. 6182-6189
Author(s):  
Dariusz M. Niedzwiedzki
Keyword(s):  
Solar Cells ◽  
Low Temperature ◽  
Optical Spectroscopy ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Dye Sensitized Solar Cells ◽  
Time Resolved ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Photophysical properties of N719 and Z907, benchmark Ru-dyes used as sensitizers in dye-sensitized solar cells, were studied by static and time-resolved optical spectroscopy at room temperature and 160 K.

scholarly journals Metasurface of Combined Semicircular Rings with Orthogonal Slit Pairs for Generation of Dual Vector Beams

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1718
Author(s):  
Qian Kong ◽  
Manna Gu ◽  
Xiangyu Zeng ◽  
Rui Sun ◽  
Yuqin Zhang ◽  
...  
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Polarized Light ◽  
Orientation Angle ◽  
Fdtd Simulation ◽  
Dual Vector ◽  
Vector Beams ◽  
Linearly Polarized ◽  
Potential Applications ◽  
Difference Time

Manipulation of multichannel vector beams (VBs) with metasurfaces is an important topic and holds potential applications in information technology. In this paper, we propose a novel metasurface for the generation of dual VBs, which is composed of orthogonal slit pairs arranged on multiple groups of combined semicircular rings (CSRs). A group of CSRs include a right-shifted set and a left-shifted set of semicircular rings, and each set of semicircular rings has two halves of circles with different radii, sharing the same shifted center. Under the illumination of linearly polarized light, the two shifted sets of semicircular rings generate the two VBs at the shifted center positions on the observation plane. The slit units of each set are designed with independent rotation order and initial orientation angle. By adjusting the linear polarization of illumination, both two VBs with their orders and polarization states are independently controlled simultaneously. The principle and design are demonstrated by the finite-difference time domain (FDTD) simulation. The work is of significance for miniatured devices of VB generators and for related applications.

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