Second-order Raman spectrum of ZnSe

1970 ◽  
Vol 48 (21) ◽  
pp. 2499-2506 ◽  
Author(s):  
J. C. Irwin ◽  
J. LaCombe
Keyword(s):  
Raman Spectrum ◽  
Theoretical Model ◽  
Second Order ◽  
Optical Phonons ◽  
Zone Boundary ◽  
Sum Rule ◽  
First Order ◽  
Zinc Blende ◽  
Order Spectrum ◽  
Phonon Spectra

The first- and second-order Raman spectra of ZnSe have been measured and an interpretation of the spectra has been carried out. The first-order spectrum yielded the values [Formula: see text] and [Formula: see text] for the longitudinal and transverse optical phonons at the center of the Brillouin zone. The zone boundary frequencies at the critical points X, L, and W have been estimated from the second-order spectrum. These frequencies were chosen to be consistent with both the experimental results and a theoretical model. The resulting values were further checked for consistency with a sum rule and by using regularities observed previously in the phonon spectra of zinc blende semiconductors.

scholarly journals Paying inattention: The art of ignoring others' work among Russian social scientists

2020 ◽  
Author(s):  
Mikhail Sokolov
Keyword(s):  
Theoretical Model ◽  
Information Search ◽  
Sociology Of Science ◽  
Second Order ◽  
Social Scientists ◽  
Critical Sociology ◽  
First Order ◽  
Science Approach ◽  
Search For Information ◽  
Knowledge Claims

Why do scholars pay attention to some works, and recognize the influence of their authors, but not others? The Mertonian approach suggests that scholars search for information instrumental in producing their knowledge claims and reward authors for making important contributions. The critical sociology of science approach explains recognition (e.g. in the form of citing) as rhetorical practices that strengthen one’s credibility. Both models fail to explain why academics sometimes ignore apparently relevant sources or how groups of scholars turn into bubbles, censoring information about findings made outside of them. According to the theoretical model suggested in this paper, what governs information search is not first-order relevance (what individual academics considers relevant), but second-order awareness (what they know their audiences are aware of). In this model, the search for information is mostly governed by the necessity to make successful claims of novelty – to present findings that are new to one’s audience. Individuals easily disregard findings their audiences are unaware of. Institutionally organized audiences thus serve as enforcers of information search, and their members may tacitly collaborate in maintaining unawareness of intellectual developments outside of their common attention space In the empirical part of the paper, we use the example of post-Soviet sociology to test the predictions following from this model: (1) that scarcity of enforcement results in an overall shrinking of individuals’ attention spaces, and in their attaining idiosyncratic configurations; (2) that when borders of audiences cross-cut legitimate classifications, attention spaces are shaped by the former, rather than the latter; (3) that as a reaction to such cross-cutting, new classifications are introduced, legitimizing existing inattention.

scholarly journals Ocean Surface Cross Section for Bistatic HF Radar Incorporating a Six DOF Oscillation Motion Model

2019 ◽  
Vol 11 (23) ◽  
pp. 2738 ◽  
Author(s):  
Yao ◽  
Xie ◽  
Huang
Keyword(s):  
Cross Sections ◽  
Ocean Surface ◽  
Second Order ◽  
Hf Radar ◽  
Motion Model ◽  
Floating Platform ◽  
Platform Motion ◽  
First Order ◽  
Order Spectrum ◽  
Six Dof

To investigate the characteristics of sea clutter, based on ocean surface electromagnetic scattering theory, the first- and second-order ocean surface scattering cross sections for bistatic high-frequency (HF) radar incorporating a multi-frequency six degree-of-freedom (DOF) oscillation motion model are mathematically derived. The derived radar cross sections (RCSs) can be reduced to the floating platform based monostatic case or onshore bistatic case for corresponding geometry setting. Simulation results show that the six DOF oscillation motion will result in more additional peaks in the radar Doppler spectra and the amplitudes and frequencies of these motion-induced peaks are decided by the amplitudes and frequencies of the oscillation motion. The effect of the platform motion on the first-order radar spectrum is greater than that of the second-order, and the motion-induced peaks in the first-order spectrum may overlap with the second-order spectrum. Furthermore, yaw is the dominant factor affecting the radar spectra, especially the second-order. Moreover, the effect of platform motion on radar spectra and the amplitudes of the second-order spectrum decreases as the bistatic angle increases. In addition, it should be noted that the amplitudes of the Bragg peaks may be lower than those of the motion-induced peaks due to the low frequency (LF) oscillation motion of the floating platform, which is an important finding for the applications of the floating platform based bistatic HF radar in moving target detection and ocean surface dynamics parameter estimation.

scholarly journals The Princeton Experiment on the Orbiting Astronomical Observatory

1971 ◽  
Vol 41 ◽  
pp. 334-335
Author(s):  
E. B. Jenkins
Keyword(s):  
Astronomical Observatory ◽  
Second Order ◽  
Guidance System ◽  
Absorption Lines ◽  
Interstellar Absorption ◽  
Entire Spectrum ◽  
First Order ◽  
Order Spectrum ◽  
Ultraviolet Spectrometer

Princeton's 80 cm diameter telescope with an ultraviolet spectrometer will be the prime experiment on board NASA's third Orbiting Astronomical Observatory (OAO-C) which is scheduled for launch in late 1971. Two scanning carriage arms within the spectrometer will each have one photomultiplier sensitive to a 1600–3200 Å first order spectrum and another photomultiplier which will register from 800 to 1600 Å in the second order. Since the primary purpose of the instrument will be to study interstellar absorption lines, the design philosophy has emphasized the role of carefully examining the detail of specific lines, rather than surveying a star's entire spectrum. Thus the carriage with the narrowest exit slits, providing 0.1 Å resolution in first order and 0.05 Å in second order, has been programmed to repetitively scan and retrace over any selected 0.7 Å interval in first order (or 0.35 Å in second order). Stepping motion in one direction every 16 s will occur for the second carriage, which will offer 0.4 and 0.2 Å resolutions for first and second orders, respectively. Approximately half of the starlight which is focussed on the entrance slit jaws is reflected into a fine guidance system which will enable the spacecraft to stabilize to within 0.1 arc sec on a star as faint as 7th magnitude.

Critical Review of Raman Spectroscopy as a Diagnostic Tool for Semiconductor Microcrystals

1989 ◽  
Vol 164 ◽  
Author(s):  
P.M Fauchet ◽  
I.H. Campbell
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectrum ◽  
Raman Scattering ◽  
Diagnostic Tool ◽  
Critical Review ◽  
Size Dependence ◽  
Second Order ◽  
First Order ◽  
Surface Vibrations

AbstractRaman scattering is becoming a widely used tool for the characterization of semiconductor microcrystals due to its sensitivity to crystal sizes below a few hundred angstroms. Through detailed analysis of the first order Raman spectrum it is possible to determine the size and shape of microcrystalline grains. First order spectra must be examined with care however, since they are sensitive to other factors including: stress/strain, surface vibrations, mixed amorphous/microcrystalline phases and intragrain defects. Second order Raman spectra are more sensitive to microcrystalline effects than first order spectra. They offer the potential to measure crystal sizes greater than a few hundred angstroms but much work remains to be done to quantify the size dependence of the second order spectra.

Critical point analysis of cubic ZnS

1970 ◽  
Vol 48 (21) ◽  
pp. 2477-2480 ◽  
Author(s):  
J. C. Irwin
Keyword(s):  
Theoretical Model ◽  
Critical Point ◽  
Infrared Spectra ◽  
Critical Points ◽  
Second Order ◽  
Experimental Results ◽  
Zone Boundary ◽  
Point Analysis ◽  
Critical Point Analysis

An interpretation of the second-order Raman and infrared spectra of cubic ZnS is given. A set of values is obtained for the phonon frequencies at the zone boundary critical points X, L, and W. These values are consistent with both the experimental results and a theoretical model. The frequencies obtained are compared with those proposed by previous workers.

A NEW HIGH LIGHT GATHERING POWER SPECTROGRAPH FOR AURORAL STUDIES

1949 ◽  
Vol 27a (6) ◽  
pp. 231-233 ◽  
Author(s):  
W. Petrie
Keyword(s):  
Wave Length ◽  
Normal Incidence ◽  
Ruled Surface ◽  
Second Order ◽  
High Light ◽  
First Order ◽  
Order Spectrum ◽  
Light Gathering Power ◽  
Light Gathering ◽  
Strong Radiation

The optics of the spectrograph consist of two f 2.5, 12 in. aircraft camera lenses, and a 15,000 lines per inch plane grating with ruled surface 4 in. by 4 in. The grating concentrates light in the second order spectrum; the dispersion in this order for normal incidence is 22 Å per mm. A few spectra were obtained during the spring of 1949, and the results appear to be most promising. These spectra include several interesting features, one of which is a strong radiation of wave length 4320 Å in the second order. This radiation is likely to be an intense first order infrared feature.

Theoretical Modeling and Simulation of Higher Order FWM Crosstalks in Multichannel WDM Optical Communication Systems

2013 ◽  
Vol 660 ◽  
pp. 130-134
Author(s):  
Arash Yazdani ◽  
Morteza Noshad ◽  
Abbas Farrokhi
Keyword(s):  
Theoretical Model ◽  
Optical Communication ◽  
Communication Systems ◽  
Higher Order ◽  
Second Order ◽  
Wdm Networks ◽  
Power Penalty ◽  
First Order ◽  
Optical Communication Systems ◽  
First Time

In this paper, we derive a theoretical model for the higher order FWM power in WDM networks with NZDSF fibers for the first time. We have investigated the higher order FWM power theoretically and by numerical simulations. Dividing the fiber into finite number of elements and applying the boundary conditions, allow us derive an expression for second order power penalty. At the end of each element we derive the first order FWM power for all wavelengths and use these values to calculate the second order FWM power in the next element. Consequently, for each channel we can compute the total second order FWM power penalty at the end of the fiber.

Manifestation of defects in phonon spectra of binary zinc-blende compounds

2004 ◽  
Vol 27 (1-3) ◽  
pp. 321-324 ◽  
Author(s):  
J. Polit ◽  
E. M. Sheregii ◽  
J. Cebulski ◽  
M. Pociask ◽  
A. Kisiel ◽  
...  
Keyword(s):  
Zinc Blende ◽  
Phonon Spectra

Nonlinear Analysis of Visual Evoked Potentials Elicited by Color Stimulation

1997 ◽  
Vol 36 (04/05) ◽  
pp. 315-318 ◽  
Author(s):  
K. Momose ◽  
K. Komiya ◽  
A. Uchiyama
Keyword(s):  
Visual System ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Normal Subjects ◽  
Second Order ◽  
First Order ◽  
The Relationship ◽  
Perceived Color ◽  
Second Order Nonlinearity ◽  
Visual Evoked

Abstract:The relationship between chromatically modulated stimuli and visual evoked potentials (VEPs) was considered. VEPs of normal subjects elicited by chromatically modulated stimuli were measured under several color adaptations, and their binary kernels were estimated. Up to the second-order, binary kernels obtained from VEPs were so characteristic that the VEP-chromatic modulation system showed second-order nonlinearity. First-order binary kernels depended on the color of the stimulus and adaptation, whereas second-order kernels showed almost no difference. This result indicates that the waveforms of first-order binary kernels reflect perceived color (hue). This supports the suggestion that kernels of VEPs include color responses, and could be used as a probe with which to examine the color visual system.

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