Nonlinear regime of surface polaritons including exciton polaritons in organic materials

2016 ◽  
Author(s):  
B. D. Fainberg ◽  
G. Li
Keyword(s):  
Organic Materials ◽  
Nonlinear Regime ◽  
Surface Polaritons ◽  
Exciton Polaritons

scholarly journals Exciton-polaritons in 2d macroporous silicon structures with nano-coatings

2020 ◽  
Vol 11 (4) ◽  
pp. 445-455
Author(s):  
L. A. Karachevtseva ◽  
◽  
O. O. Lytvynenko ◽  
V. F. Onyshchenko ◽  
V. V. Strelchuk ◽  
...  
Keyword(s):  
Large Scale ◽  
Oscillation Period ◽  
Einstein Condensation ◽  
Ir Absorption ◽  
Reflection Spectra ◽  
Macroporous Silicon ◽  
Band Bending ◽  
Surface Polaritons ◽  
Exciton Polaritons ◽  
Silicon Structures

In this paper, we investigated high-resolution IR absorption and reflection spectra in one-sided periodical 2D macroporous silicon structures with nano-coatings of SiO2 and CdS, ZnO nanoparticles, as well as two-sided structures of macroporous silicon without nano-coatings. After changing the resolution of spectra measurements from 2 to 1 cm–1, the oscillation period of Wannier-Stark electro-optical effect decreases by 3 times, and absorption increases by 60–100 times; and for two-sided structures the oscillation period decreases by 1.5 times and absorption increases by 25–30 %. In addition, giant absorption oscillations with positive and negative amplitudes of 107 arb. un. were evaluated in spectral regions of Si–Si–bonds and Pb centers. Similar oscillations in the reflection spectra have much less amplitudes up to 4·104 arb. un. In the spectral area of the transverse phonon ωTO (Si–Si–bonds) absorption spectra of 2D macroporous silicon structures consistent fully with data for phonon polaritons in microresonators as a result of resonance interaction of dipole-active vibrations with the frequency of ωTO in thin films with the surface modes of microresonator. In addition, microresonators interact both with each other in one-sided macroporous silicon structures and in the system of two-sided macroporous silicon. The giant absorption oscillations testify the strong interaction of surface polaritons with photons. The coherence of oscillations and large-scale spatial correlation are а result of exciton-polariton condensation on macropores as microresonators. In 2D macroporous silicon structures with nano-coatings band bending on the surface of the macropores are significant. Therefore, the generated photoelectrons link with holes, forming electron-hole pairs named as exciton-polaritons according to phenomenon of Bose-Einstein condensation.

Application of Improved Voltage Compensation in the SEM to Imaging of Organic Materials

1973 ◽  
Vol 31 ◽  
pp. 444-445
Author(s):  
P.J. Killingworth ◽  
M. Warren
Keyword(s):  
Electron Beam ◽  
Organic Materials ◽  
Operating Parameters ◽  
Low Density ◽  
Beam Diameter ◽  
Incident Electron Beam ◽  
Specimen Material ◽  
Voltage Compensation ◽  
Selection Of ◽  
Scanning Electron

Ultimate resolution in the scanning electron microscope is determined not only by the diameter of the incident electron beam, but by interaction of that beam with the specimen material. Generally, while minimum beam diameter diminishes with increasing voltage, due to the reduced effect of aberration component and magnetic interference, the excited volume within the sample increases with electron energy. Thus, for any given material and imaging signal, there is an optimum volt age to achieve best resolution.In the case of organic materials, which are in general of low density and electric ally non-conducting; and may in addition be susceptible to radiation and heat damage, the selection of correct operating parameters is extremely critical and is achiev ed by interative adjustment.

200kv superconducting cryo electron microscope

1987 ◽  
Vol 45 ◽  
pp. 642-643
Author(s):  
M. Iwatsuki ◽  
Y. Kokubo ◽  
Y. Harada ◽  
J. Lehman
Keyword(s):  
Electron Microscope ◽  
Structure Analysis ◽  
Organic Materials ◽  
Strong Interactions ◽  
Specimen Preparation ◽  
Great Effort ◽  
Electron Microscopic ◽  
Crystal Fields ◽  
Special Skill ◽  
Long Time

In recent years, the electron microscope has been significantly improved in resolution and we can obtain routinely atomic-level high resolution images without any special skill. With this improvement, the structure analysis of organic materials has become one of the interesting targets in the biological and polymer crystal fields.Up to now, X-ray structure analysis has been mainly used for such materials. With this method, however, great effort and a long time are required for specimen preparation because of the need for larger crystals. This method can analyze average crystal structure but is insufficient for interpreting it on the atomic or molecular level. The electron microscopic method for organic materials has not only the advantage of specimen preparation but also the capability of providing various information from extremely small specimen regions, using strong interactions between electrons and the substance. On the other hand, however, this strong interaction has a big disadvantage in high radiation damage.

STM of freeze-fracture replicas: Problems and promises

1993 ◽  
Vol 51 ◽  
pp. 68-69
Author(s):  
J. T. Woodward ◽  
J. A. N. Zasadzinski
Keyword(s):  
Scanning Tunneling Microscope ◽  
Organic Materials ◽  
Freeze Fracture ◽  
Atomic Resolution ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
Molecular Scale ◽  
Organic Surfaces ◽  
Metal Layers ◽  
Conductive Surfaces

The Scanning Tunneling Microscope (STM) offers exciting new ways of imaging surfaces of biological or organic materials with resolution to the sub-molecular scale. Rigid, conductive surfaces can readily be imaged with the STM with atomic resolution. Unfortunately, organic surfaces are neither sufficiently conductive or rigid enough to be examined directly with the STM. At present, nonconductive surfaces can be examined in two ways: 1) Using the AFM, which measures the deflection of a weak spring as it is dragged across the surface, or 2) coating or replicating non-conductive surfaces with metal layers so as to make them conductive, then imaging with the STM. However, we have found that the conventional freeze-fracture technique, while extremely useful for imaging bulk organic materials with STM, must be modified considerably for optimal use in the STM.

Stabilizing pyritic material

1989 ◽  
Vol 4 ◽  
pp. 244-248 ◽  
Author(s):  
Donald L. Wolberg
Keyword(s):  
Significant Contribution ◽  
Organic Materials ◽  
Sedimentary Rocks ◽  
Iron Sulfides ◽  
Decomposition Products ◽  
Iron Minerals ◽  
Pyrite Formation ◽  
Organic Sediments ◽  
Freshwater Environments

The minerals pyrite and marcasite (broadly termed pyritic minerals) are iron sulfides that are common if not ubiquitous in sedimentary rocks, especially in association with organic materials (Berner, 1970). In most marine sedimentary associations, pyrite and marcasite are associated with organic sediments rich in dissolved sulfate and iron minerals. Because of the rapid consumption of sulfate in freshwater environments, however, pyrite formation is more restricted in nonmarine sediments (Berner, 1983). The origin of the sulfur in nonmarine environments must lie within pre-existing rocks or volcanic detritus; a relatively small, but significant contribution may derive from plant and animal decomposition products.

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