First-order spectrum in the pseudoharmonic approximation and the approximation of renormalized cubic anharmonicity

1979 ◽  
Vol 31 (2) ◽  
pp. 1009-1013
Author(s):  
D. V. Alekseev
Keyword(s):  
First Order ◽  
Order Spectrum ◽  
Pseudoharmonic Approximation

Disorder-Induced Low-Frequency Raman Band Observed in Deposited MoS2 Films

1994 ◽  
Vol 48 (6) ◽  
pp. 733-736 ◽  
Author(s):  
N. T. McDevitt ◽  
J. S. Zabinski ◽  
M. S. Donley ◽  
J. E. Bultman
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Raman Band ◽  
Low Frequency ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
First Order ◽  
Order Spectrum ◽  
History Of ◽  
Frequency Feature

Crystalline disorder in thin films plays an important role in determining their properties. Disorder in the crystal structure of MoS2 films prepared by magnetron sputtering and pulsed laser deposition was evaluated with the use of Raman spectroscopy. The peak positions and bandwidths of the first-order Raman bands, in the region 100 to 500 cm−1, were used as a measure of crystalline order. In addition, a low-frequency feature was observed at 223 cm−1 that is not part of the normal first-order spectrum of a fully crystalline specimen. Data presented here demonstrate that this band is characteristic of crystalline disorder, and its intensity depends on the annealing history of the film. This behavior seems to be analogous to the disorder found in graphite thin films.

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.

Adaptive Kalman Filtering: A Simulation Result

1988 ◽  
Vol 110 (1) ◽  
pp. 104-107 ◽  
Author(s):  
J. Z. Sasiadek ◽  
P. J. Wojcik
Keyword(s):  
Kalman Filtering ◽  
Design Methodology ◽  
Signal To Noise Ratio ◽  
Performance Tests ◽  
Signal To Noise ◽  
First Order ◽  
Order Spectrum ◽  
On Line ◽  
Sensor Signals ◽  
Unknown Signal

This paper presents the algorithm for on-line adaptive Kalman filtering of sensor signals with unknown signal to noise ratio. A first order spectrum of a pure signal and white Gaussian measurement noise have been assumed. The results of the performance tests of the algorithm as well as the design methodology of the adaptive filter are given.

THE PROTON MAGNETIC RESONANCE SPECTRUM OF CYCLOPROPYLAMINE, THE A2A2′X CASE WITH STRONG CROSS-COUPLING: A PSEUDO FIRST-ORDER SPECTRUM WITH COMBINATION LINES

1963 ◽  
Vol 41 (11) ◽  
pp. 2774-2780 ◽  
Author(s):  
H. M. Hutton ◽  
T. Schaefer
Keyword(s):  
Proton Magnetic Resonance ◽  
Resonance Spectrum ◽  
Cross Coupling ◽  
Proton Magnetic Resonance Spectrum ◽  
Coupling Constants ◽  
Proton Spectrum ◽  
First Order ◽  
Order Spectrum ◽  
Complete Set ◽  
Pseudo First Order

By means of the anisotropic solvent effect of benzene on the ring protons of cyclopropylamine the proton spectrum is converted to A2A2′X. Since the cross-coupling from the A2 to the A2′ protons is large the spectrum does not approximate to a pseudo first-order AX4 spectrum. Instead, it is one which may be described as pseudo first-order with combination lines. The presence of the latter allows a fairly complete set of coupling constants to be derived in a simpler way than by a computer attack on the general A2B2X spectrum. Conversely, the approach developed here, when applicable, allows the derivation of reliable input parameters for a computer program. From the temperature dependence of the A2A2′X case the A2 and A2′ protons can be distinguished and it is found that the protons trans to the amino group are preferentially shifted to high field by the benzene molecules.

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.

pH-Induced Difference, Spectrophotometric Assay of Tetracycline and Oxytetracycline

1985 ◽  
Vol 68 (5) ◽  
pp. 1045-1048
Author(s):  
Abdel-Aziz M Wahbi ◽  
Magda Barary ◽  
Hoda Mahgoub ◽  
M Abdel-Hady Elsayed
Keyword(s):  
Linear Relationship ◽  
Good Accuracy ◽  
Spectrophotometric Assay ◽  
Ph Change ◽  
Displacement Effect ◽  
First Order ◽  
Spectrophotometric Methods ◽  
Order Spectrum ◽  
Relationship Of

Abstract The △D1 method is based on the measurement of the quotient of the first order spectrum displacement effect induced by a pH change as a function of tetracycline-oxytetracycline concentration. The linear relationship of such variables with negligible intercept values permits the assay of these drugs in commercial capsule preparations, with good accuracy and reproducibility. The assay results were compared with other spectrophotometric methods: Amax, △A, and D1,

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.

Sign in / Sign up

Export Citation Format

Share Document