A Comparison of Theoretical and Experimental Raman Spectra of Microhydrated Sodium Glycinate

2014 ◽  
Vol 934 ◽  
pp. 116-120
Author(s):  
Chen Dong ◽  
Zhi Chao Wei ◽  
Bo Liu
Keyword(s):  
Raman Spectra ◽  
Structural Information ◽  
Sodium Cation ◽  
Bridge Site ◽  
Charge Site ◽  
Dominant Position

The sequential microhydration of sodium glycinate is investigated at the MP2/6-311++G(d,p) level. Our results clearly indicate that the microhydration process is driven by the charge site of sodium cation and a bridge site is losing its dominant position. Eventually, a comparison of theoretical and experimental Raman spectra provides the evidence of the predicted structural information.

Application of Waveguide Raman Spectroscopy to High-Index Dielectric Films

1988 ◽  
Vol 42 (2) ◽  
pp. 326-330 ◽  
Author(s):  
David R. Tallant ◽  
Karen L. Higgins ◽  
Alan F. Stewart
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Structural Information ◽  
Single Layer ◽  
Amorphous Film ◽  
Fused Silica ◽  
Oxide Thin Film ◽  
Dielectric Films ◽  
Refractory Oxide ◽  
Silica Substrate

Waveguide Raman spectroscopy has been applied to the analysis of single-layer, refractory-oxide, thin-film coatings on fused silica. With the use of the film as a waveguide, the interaction of the laser probe beam with the film is maximized, and interference from the silica substrate is minimized. An amorphous film of Ta2O5 was found to be an excellent waveguide, yielding an intense Raman spectrum. Even though polycrystalline films of Y2O3, ZrO2, HfO2, and ThO2 were found to be poor waveguides, they still yielded Raman spectra containing useful structural information. Such Raman spectra showed that the ThO2 film was initially in an unusual structural form, which spontaneously transformed into cubic ThO2. Even for films yielding relatively weak Raman bands, substrate Raman scattering was not a serious interference. Representative spectra are presented, along with a brief discussion of the requirements for coupling optical beams into films with large refractive indices.

Interpretation of Raman Spectra of Nitro-Containing Explosive Materials. Part II: The Implementation of Neural, Fuzzy, and Statistical Models for Unsupervised Pattern Recognition

1997 ◽  
Vol 51 (12) ◽  
pp. 1868-1879 ◽  
Author(s):  
Nelson W. Daniel ◽  
Ian R. Lewis ◽  
Peter R. Griffiths
Keyword(s):  
Pattern Recognition ◽  
Raman Spectra ◽  
Fuzzy Clustering ◽  
Statistical Models ◽  
Structural Information ◽  
A Priori ◽  
Data Set ◽  
Pattern Recognition Techniques ◽  
Explosive Materials ◽  
Neural Fuzzy

The implementation of neural, fuzzy, and statistical models for the unsupervised pattern recognition and clustering of Fourier transform (FT)-Raman spectra of explosive materials is reported. In this work a statistical pattern recognition technique based on the concept of nearest-neighbors classification is described. Also the first application of both fuzzy clustering and a fuzzified Kohonen clustering network for the analysis of vibrational spectra is presented. Fuzzified Kohonen networks were found to perform as well as or better than the traditional fuzzy clustering technique. The unsupervised pattern recognition techniques, without the need for a priori structural information, yielded results which were comparable with those obtained by using a combination of a priori structural information and manual group-frequency analysis. This work demonstrates, via the use of a nitro-containing explosive data set, the utility of unsupervised pattern recognition techniques for the clustering, novelty detection, prototyping, and feature mapping of Raman spectra. The results of this work are directly applicable to the characterization of Raman spectra of explosives recorded with fiber-optic sampling.

Characterization of Crystalline Phases in Fly Ash by Microfocus Raman Spectroscopy

1984 ◽  
Vol 43 ◽  
Author(s):  
Barry E. Scheetz ◽  
William B. White
Keyword(s):  
Raman Spectroscopy ◽  
Fly Ash ◽  
Raman Spectra ◽  
Structural Information ◽  
Crystalline Phases ◽  
Individual Basis ◽  
Laser Raman ◽  
Raman Microprobe

AbstractThe laser Raman microprobe was used to interrogate individual fly ash particles as small as 1 μm diameter and record “fingerprint” Raman spectra from both crystalline and non-crystalline components.of the fly ash. When compared to reference patterns of known crystalline phases, the Raman spectra can be used to identify crystalline phases and can give some structural information on other phases. Furthermore, because this method characterizes fly ash particles on an individual basis, correlations to both color and morphology of the particles can be made.

Vibrational Properties of a-Si:H Films Containing Voids: Experiment and Modeling

1999 ◽  
Vol 557 ◽  
Author(s):  
N. Barriquand ◽  
V. Paillard ◽  
P. Roca i Cabarrocas ◽  
G. Landa ◽  
M. Djafari-Rouhani
Keyword(s):  
Amorphous Silicon ◽  
Raman Spectra ◽  
Structural Information ◽  
Hydrogenated Amorphous Silicon ◽  
Silicon Films ◽  
Atomic Scale ◽  
Vibrational Properties ◽  
Scale Modeling ◽  
Macroscopic Properties ◽  
Hydrogenated Amorphous

AbstractIn this paper, we present results about the vibrational properties of hydrogenated amorphous silicon films. We expect to explain the slight differences observed in the Raman spectra using atomic-scale modeling. In particular, we focuse on the correlation of our results to the density of samples. This should give quantitative structural information which could be correlated to both macroscopic properties and elaboration conditions.

Raman Spectroscopy of Barium Titanate Thin Films

1994 ◽  
Vol 341 ◽  
Author(s):  
Lawrence H. Robins ◽  
Debra L. Kaiser ◽  
Lawrence D. Rotter ◽  
Gregory T. Stauf
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Structural Information ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Cubic Phase ◽  
Bulk Single Crystal ◽  
X Ray ◽  
Film Substrate

AbstractRaman spectroscopy was used to examine the structure of polycrystalline and epitaxial barium titanium oxide thin films grown by metal-organic chemical vapor deposition. The Raman spectra confirmed the presence of the tetragonal ferroelectric phase of BaTiO3 and also revealed several other Ba-Ti-O phases. These films were also characterized by X-ray diffraction and TEM imaging. The structural information provided by the Raman spectra was qualitatively consistent with the X-ray and TEM results. The temperature dependencies of the Raman spectra of two films were examined in the range 25°C-175°C. Raman peaks due to tetragonal BaTiO3 were observed at temperatures well above 132°C, which is the tetragonal-cubic phase transition temperature for bulk single-crystal BaTiO3. This may indicate stabilization of the tetragonal phase by an anisotropic film-substrate interaction or by inter-grain stresses.

Measurement and Reduction of Radiation Damage in Frozen Hydrated Crystalline Specimens

1978 ◽  
Vol 36 (3) ◽  
pp. 70-77 ◽  
Author(s):  
R.M. Glaeser ◽  
S.B. Hayward
Keyword(s):  
Diffraction Pattern ◽  
Structural Information ◽  
Structural Disorder ◽  
Structural Features ◽  
Biological Macromolecules ◽  
Diffraction Intensity ◽  
Object Structure ◽  
Specimen Material ◽  
Unit Cells ◽  
Identical Unit

Highly ordered or crystalline biological macromolecules become severely damaged and structurally disordered after a brief electron exposure. Evidence that damage and structural disorder are occurring is clearly given by the fading and eventual disappearance of the specimen's electron diffraction pattern. The fading and disappearance of sharp diffraction spots implies a corresponding disappearance of periodic structural features in the specimen. By the same token, there is a oneto- one correspondence between the disappearance of the crystalline diffraction pattern and the disappearance of reproducible structural information that can be observed in the images of identical unit cells of the object structure. The electron exposures that result in a significant decrease in the diffraction intensity will depend somewhat upon the resolution (Bragg spacing) involved, and can vary considerably with the chemical makeup and composition of the specimen material.

Direct visualization of phase-separated domains in lipid membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 290-291
Author(s):  
S. W. Hui ◽  
T. P. Stewart
Keyword(s):  
Lipid Membranes ◽  
Structural Information ◽  
Freeze Fracture ◽  
Biological Molecules ◽  
Vacuum Drying ◽  
Direct Visualization ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Hydrocarbon Chains

Direct electron microscopic study of biological molecules has been hampered by such factors as radiation damage, lack of contrast and vacuum drying. In certain cases, however, the difficulties may be overcome by using redundent structural information from repeating units and by various specimen preservation methods. With bilayers of phospholipids in which both the solid and fluid phases co-exist, the ordering of the hydrocarbon chains may be utilized to form diffraction contrast images. Domains of different molecular packings may be recgnizable by placing properly chosen filters in the diffraction plane. These domains would correspond to those observed by freeze fracture, if certain distinctive undulating patterns are associated with certain molecular packing, as suggested by X-ray diffraction studies. By using an environmental stage, we were able to directly observe these domains in bilayers of mixed phospholipids at various temperatures at which their phases change from misible to inmissible states.

High-Resolution Scanning Electron Microscopy of Biological Specimens

1988 ◽  
Vol 46 ◽  
pp. 186-187
Author(s):  
M. Müller ◽  
R. Hermann
Keyword(s):  
High Resolution ◽  
Freeze Drying ◽  
Room Temperature ◽  
Structural Information ◽  
Freeze Substitution ◽  
Critical Point Drying ◽  
Sem Study ◽  
Major Factors ◽  
Structural Preservation ◽  
Preparation Techniques

Three major factors must be concomitantly assessed in order to extract relevant structural information from the surface of biological material at high resolution (2-3nm).Procedures based on chemical fixation and dehydration in graded solvent series seem inappropriate when aiming for TEM-like resolution. Cells inevitably shrink up to 30-70% of their initial volume during gehydration; important surface components e.g. glycoproteins may be lost. These problems may be circumvented by preparation techniques based on cryofixation. Freezedrying and freeze-substitution followed by critical point drying yields improved structural preservation in TEM. An appropriate preservation of dimensional integrity may be achieved by freeze-drying at - 85° C. The sample shrinks and may partially collapse as it is warmed to room temperature for subsequent SEM study. Observations at low temperatures are therefore a necessary prerequisite for high fidelity SEM. Compromises however have been unavoidable up until now. Aldehyde prefixation is frequently needed prior to freeze drying, rendering the sample resistant to treatment with distilled water.

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