Raman Spectra of Ion Intercalated Vermiculites

1987 ◽  
Vol 111 ◽  
Author(s):  
H. X. Jiang ◽  
S. A. Solin ◽  
H. Kim ◽  
T. J. Pinnavaia
Keyword(s):  
Raman Spectra ◽  
Nearest Neighbor ◽  
Van Der Waals ◽  
Mode Frequency ◽  
Basal Spacing ◽  
Physical Parameters ◽  
Force Model ◽  
Torsional Mode ◽  
Calculation Results ◽  
Neighbor Approximation

AbstractThe Raman spectra of ion intercalated Vermiculites have been studied. The torsional mode frequencies exhibit a shift to higher energy with increasing basal spacing d. Using a van der Waals type force model, and the nearest neighbor approximation, we have successfully derived the formula for the torsional mode frequency as functions of basal spacing d and other physical parameters. The calculation results are quite consistent with the experimental observations.

Interactions dans une chaîne de sphères ou de cavités alignées. Plasmons de surface et énergie de Van der Waals

1977 ◽  
Vol 55 (16) ◽  
pp. 1407-1422 ◽  
Author(s):  
A. Ronveaux ◽  
A. Moussiaux ◽  
A. A. Lucas
Keyword(s):  
Power Series ◽  
Surface Plasmon ◽  
Nearest Neighbor ◽  
Van Der Waals ◽  
Nearest Neighbors ◽  
Distance Ratio ◽  
First Approximation ◽  
Spherical Cavities ◽  
Plasmon Oscillation ◽  
Neighbor Approximation

The eigenmodes of surface plasmon oscillation for an arbitrary number of aligned spheres or spherical cavities are given by a power series of the radius–distance ratio. The Van der Waals energy is calculated in first approximation for an arbitrary chain, and in second approximation for an array of two holes and two spheres.The error due to the neglect of all interactions except that between nearest neighbors is analysed in detail together with the bands of the infinite chain in the nearest neighbor approximation. [Journal translation]

Raman investigations of collective vibrational motions in van der Waals liquids

1985 ◽  
Vol 63 (7) ◽  
pp. 2047-2053 ◽  
Author(s):  
S. Bratos ◽  
G. Tarjus
Keyword(s):  
Experimental Data ◽  
Raman Spectra ◽  
Van Der Waals ◽  
Zero Order ◽  
Partially Coherent ◽  
Present Context

Recent investigations of collective vibrational motions in pure van der Waals liquids and in their isotopic mixtures are reviewed. Experimental data are enumerated first. The theory is presented later, separately, for non-composite and composite bands of both isotropic and anisotropic Raman spectra. It is shown that isotropic Raman processes are partially coherent and contain information about collective vibrational motions in liquids. In turn, anisotropic Raman processes are incoherent in the zero-order description and their study is less important in the present context.

scholarly journals Phase Transition and Polymerization of Acetonitrile under High Pressure

2014 ◽  
Vol 70 (a1) ◽  
pp. C763-C763
Author(s):  
Haiyan Zheng ◽  
Kuo Li ◽  
George Cody ◽  
Chris Tulk ◽  
Jamie Molaison ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Reaction Mechanism ◽  
Neutron Diffraction ◽  
Raman Spectra ◽  
Hydrogen Transfer ◽  
Layer Structure ◽  
Van Der Waals ◽  
Orthorhombic Phase ◽  
Organic Polymer

Successful application of high pressure on synthesis of organic polymer, including the conducting polymer and super hard materials depends on the knowledge of reaction mechanism. The evolution of crystal structure under high pressure especially the structure close to transition pressure is crucial to conclude the reaction mechanism. Nitriles represent a large class of interstellar molecules and are the potential source of amino acids. Understanding its behavior at extreme conditions has gained increasing attention recently. Acetonitrile (CH3CN), the simplest organic compound with C≡N triple bond, can act as a model system for studying the pressure induced polymerization. The phase transition of acetonitrile under high pressure has been studied extensively.[1-3] However, it is still controversial and there is no any detailed discussion about its polymerization mechanism under high pressure. Here, we report the in-situ high pressure Raman spectra and powder neutron diffraction results on CD3CN, which indicates a minor phase transition at 5 GPa. The neutron diffraction shows that CD3CN keeps the orthorhombic phase from 1.66 GPa to 20.58 GPa which is very close to the reaction pressure. The week hydrogen bonding CD...N arranges the molecule into 3-dimensional framework which can be treated as two sets of diamond like structures interpenetrating with each other. Interestingly, the observed N...D distance is 1.984 Å at 20.58 GPa, shorter than the van der Waals distance of N...H (2.75 Å) by 28%. The van der Waals separation is often taken as a reference distance for the molecular instability. Thus, a hydrogen transfer process during the polymerization can be concluded. This deduction is also supported by the solid state NMR and FTIR results of the recovered polymerized CH3CN (p-CH3CN) from high pressure. In addition, the atomic pair distribution function and Raman spectra indicate the p-CD3CN or p-CH3CN has a random packed layer structure with nano-graphene lattice.

scholarly journals Research on Blade-Casing Rub-Impact Mechanism by Experiment and Simulation in Aeroengines

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jie Hong ◽  
Tianrang Li ◽  
Zhichao Liang ◽  
Dayi Zhang ◽  
Yanhong Ma
Keyword(s):  
High Speed ◽  
High Performance ◽  
Element Model ◽  
Physical Parameters ◽  
Test Rig ◽  
Calculation Results ◽  
Rotor Support ◽  
Blade Tip ◽  
Set Up ◽  
The Impact

Aeroengines pursue high performance, and compressing blade-casing clearance has become one of the main ways to improve turbomachinery efficiency. Rub-impact faults occur frequently with clearance decreasing. A high-speed rotor-support-casing test rig was set up, and the mechanism tests of light and heavy rub-impact were carried out. A finite element model of the test rig was established, and the calculation results were in good agreement with the experimental results under both kinds of rub-impact conditions. Based on the actual blade-casing structure model, the effects of the major physical parameters including imbalance and material characteristics were investigated. During the rub-impact, the highest stress occurs at the blade tip first and then it is transmitted to the blade root. Deformation on the impact blade tip generates easily with decreased yield strength, and stress concentration at the blade tip occurs obviously with weaker stiffness. The agreement of the computation results with the experimental data indicates the method could be used to estimate rub-impact characteristics and is effective in design and analyses process.

Vibrational Assignments of Organosilanetriols. II. Crystalline Phenylsilanetriol and Phenylsilanetriol-D3

1978 ◽  
Vol 32 (5) ◽  
pp. 469-479 ◽  
Author(s):  
H. Ishida ◽  
J. L. Koenig
Keyword(s):  
Fourier Transform ◽  
Raman Spectra ◽  
Vibrational Modes ◽  
Torsional Mode ◽  
Vibrational Assignments ◽  
Laser Raman ◽  
Sioh Group ◽  
Laser Raman Spectra ◽  
Out Of Plane ◽  
Bending Modes

Fourier transform infrared spectra (3800 to 450 cm−1) and laser Raman spectra (4000 to 0 cm−1) of crystalline phenylsilanetriol and phenylsilanetriol-d3, and liquid state phenylsilanetriol and phenylsilanetriol-d3 are first reported. Complete band assignments are attempted. All vibrational modes of the SiOH group except for the SiC torsional mode, including the SiOH in-plane and out-of-plane bending modes, are observed. In addition to the phenylsilanetriols, infrared and laser Raman spectra of crystalline diphenylsilanediol and triphenylsilanol are also studied to aid the band assignments.

Stable Divergence Angles of a Magnetic Dipole Spiral Array

1997 ◽  
Vol 11 (24) ◽  
pp. 1069-1075
Author(s):  
X. D. Fan ◽  
L. A. Bursill
Keyword(s):  
Nearest Neighbor ◽  
Initial Conditions ◽  
Equations Of Motion ◽  
Divergence Angle ◽  
Magnetic Dipoles ◽  
Analytical Proof ◽  
The Difference ◽  
Spiral Array ◽  
Map Analysis ◽  
Neighbor Approximation

An analytical model is introduced for the experiment of Douady and Couder [Phys. Rev. Lett.68, 2098 (1992), where phyllotactic patterns appear as a dynamical result of the interaction between magnetic dipoles. The difference equation for the divergence angle (i.e. the angle between successive radial vectors) is obtained by solving the equations of motion with a second nearest neighbor (SNN) approximation. A one-dimensional map analysis as well as a comprehensive analytical proof shows that the divergence angle always converges to a single attractor regardless of the initial conditions. This attractor is approximately the Fibonacci angle(~ 138°) within variations due to a growth factor μ of the pattern. The system is proved to be stable with the SNN approximation. Further analysis with a third nearest neighbor approximation (TNN) shows extra linearly stable attractors may appear around the Lucas angle (~ 99.5°).

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