Fine structure spectroscopic

Foster A. L., Breit G. N., Whitney J. W., Welch A. H., Yount J. C., Alam M. K., Islam M. N., Islam M. S., Karim M., and Manwar A. (2000) X-ray absorption fine structure spectroscopic investigation of arsenic species in soil and aquifer sediments from Brahmanbaria, Bangladesh. 4th Annual Arsenic Conference, San Diego, June 18-22, 2000. 

Hahner, G., A. Marti, N.D. Spencer, and W.R. Caseri. 1996. Orientation and electronic structure of methylene blue on mica A near edge x-ray absorption fine structure spectroscopic study. J. Chem. Phys. 104 7749-7757. 

GejfASj,Si jf j, glasses (filled symbols) with x y = 1 1. Reprinted with permission from Sen S. and Aitken B. G., Atomic structure and chemical order in Ge-As selenide and sulfoselenide glasses an x-ray absorption fine structure spectroscopic study, Phys. Rev. B, 66, 134204-10 (2002). Copyright (2002) by the American Ph5rsical Society. 

EXAFS Extended X-ray absorption fine structure spectroscopy. A spectroscopic technique which can determine interatomic distances very precisely. 

Spectroscopic methods have been successfully applied to the elucidation of some details of the fine structure of isoxazole derivatives. Thus IR spectra revealed steric hindrance in the case of some 3,4,5-trisubstituted isoxazoles for phenylisoxazoles this results in the nonplanarity of the benzene and isoxazole rings and decreasing mutual interaction. 

In general, several spectroscopic techniques have been applied to the study of NO, removal. X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) are currently used to determine the surface composition of the catalysts, with the aim to identify the cationic active sites, as well as their coordinative environment. 

Final justification for using terms such as inner- or outer-sphere awaits direct spectroscopic confirmation. Electron Spin Resonance, Mossbauer, and Fourier Transform Infrared-Cylindrical Internal Reflection Spectroscopic techniques are being used to establish the structure of surface complexes (see, e.g., McBride, Ambe et al., and Zeltner et al., this volume). The potential for using EXAFS (extended x-ray absorption fine structure) to establish the type of surface complex for Pb + adsorbing onto goethite is currently being undertaken in our laboratory. 

The task in using these simple expressions (7) and (8) lies in finding the number of ligands n, the force constants Xt./o> and values for the bond length difference Ar. The values of n and Arare obtained from X-ray crystallographic or extended X-ray absorption fine structure data. The force constants /, and fs are obtained from available vibrational spectroscopic data using the equation. 

In solid state physics, the sensitivity of the EELS spectrum to the density of unoccupied states, reflected in the near-edge fine structure, makes it possible to study bonding, local coordination and local electronic properties of materials. One recent trend in ATEM is to compare ELNES data quantitatively with the results of band structure calculations. Furthermore, the ELNES data can directly be compared to X-ray absorption near edge structures (XANES) or to data obtained with other spectroscopic techniques. However, TEM offers by far the highest spatial resolution in the study of the densities of states (DOS). 

The three aromatic amino acids (Phe, Tyr, Trp) have side-chain groups corresponding to the benzene, phenol, and indole chromophores, respectively. The spectroscopic properties of the rat transitions in these chromophores have been reviewed.136-381 Coupling of aromatic transitions among themselves and with peptide transitions can give rise to CD bands in the near and far (k < 250 nm) UV. Near-UV CD bands are useful indicators of the environment of the aromatic chromophores and can frequently be assigned to specific types of side chain, based upon band position, presence of vibrational fine structure, etc. Far-UV CD bands due to aromatic side chains, except for the La band of Tyr (-230 nm) and the Bb band of Trp (-225 nm), are generally difficult to resolve from peptide CD bands and can complicate the conformational analysis of peptides. 

The fine structure of the three cassiaoccidentalins with a 6-C (2"-0-rhamnosyl) 6-deoxy-ribo-hexos-3-ulosyl moiety was established on the basis of spectroscopic evidence, as already mentioned the H and C NMR spectra showed signals of two conformers due to hindered rotation around the C-6-glycosidic linkage, with duplication or broadening of the signals remaining even at elevated temperatures. The NOESY spectrum showed a cross-peak between H-8 of the flavone nucleus and H-6 " of the rhamnose for the major conformer and a cross-peak between OH-5 and rhamnose H-2 " for the minor conformer. 

In order to identify the spin multiplicity of the tris(carbene), field-swept two-dimensional electron spin transient nutation (2D-ESTN) spectroscopy was used. This technique is based on pulsed fourier transform (FT) EPR spectroscopic methods and is capable of elaborating straightforward information on electronic and environmental strucmres of high-spin species even in amorphous materials, information that conventional CW EPR cannot provide. The nutation spectra unequivocally demonstrated that the observed fine structure spectrum is due to a septet spin state. 

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