Electronic structure absorption spectroscopy

Hudson BS and Kohler BE (1973) Polyene spectroscopy the lowest energy excited singlet state ofdiphenyloctatetraene and other linear polyenes. J Chem Phys 59 4984-5002 Hudson BS and Kohler BE (1974) Linear polyene electronic structure and spectroscopy. Ann Rev Phys Chem 25 437-460 Hudson BS and Kohler BE (1984) Electronic stmcture and spectra of finite linear polyenes. Synthetic Metals 9 241-253 Hudson BS, Ridyard JN and Diamond J (1976) Polyene spectroscopy. Photoelectron spectra of the diphenylpolyenes. J Am Chem Soc 98 1126-1129 Hudson BS, Kohler BE and Schulten K (1982) Linear polyene electronic structure and potential surfaces. In Lim EC (ed) Excited States, Vol 6, pp 1-95. Academic Press, New York Jones PF, Jones WJ and Davies B (1992) Direct observation of the 2 Ag electronic state of carotenoid molecules by consecutive two-photon absorption spectroscopy. Photochem Photohiol A Chem, 68 59-75... 

As with other diffraction techniques (X-ray and electron), neutron diffraction is a nondestructive technique that can be used to determine the positions of atoms in crystalline materials. Other uses are phase identification and quantitation, residual stress measurements, and average particle-size estimations for crystalline materials. Since neutrons possess a magnetic moment, neutron diffraction is sensitive to the ordering of magnetically active atoms. It differs from many site-specific analyses, such as nuclear magnetic resonance, vibrational, and X-ray absorption spectroscopies, in that neutron diffraction provides detailed structural information averaged over thousands of A. It will be seen that the major differences between neutron diffraction and other diffiaction techniques, namely the extraordinarily... 

In an earlier work, we have proposed a theoretical procedure for the spectroscopy of antiferromagnetically (AF) coupled transition-metal dimers and have successfully applied this approach to the electronic absorption spectrum of model 2-Fe ferredoxin. In this work we apply this same procedure to the [Fe2in - 82) P o - CeH48)2)2 complex in order to better understand the electronic structure of this compound. As in our previous work" we base our analysis on the Intermediate Neglect of the Differential Overlap model parameterized for spectroscopy (INDO/S), utilizing a procedure outlined in detail in Reference 4. 

Porphyrin is a multi-detectable molecule, that is, a number of its properties are detectable by many physical methods. Not only the most popular nuclear magnetic resonance and light absorption and emission spectroscopic methods, but also the electron spin resonance method for paramagnetic metallopor-phyrins and Mossbauer spectroscopy for iron and tin porphyrins are frequently used to estimate the electronic structure of porphyrins. By using these multi-detectable properties of the porphyrins of CPOs, a novel physical phenomenon is expected to be found. In particular, the topology of the cyclic shape is an ideal one-dimensional state of the materials used in quantum physics [ 16]. The concept of aromaticity found in fuUerenes, spherical aromaticity, will be revised using TT-conjugated CPOs [17]. 

Determination of the Atomic and Electronic Structure of Platinum Catalysts by X-ray Absorption Spectroscopy... 

X-ray absorption spectroscopy combining x-ray absorption near edge fine structure (XANES) and extended x-ray absorption fine structure (EXAFS) was used to extensively characterize Pt on Cabosll catalysts. XANES Is the result of electron transitions to bound states of the absorbing atom and thereby maps the symmetry - selected empty manifold of electron states. It Is sensitive to the electronic configuration of the absorbing atom. When the photoelectron has sufficient kinetic energy to be ejected from the atom It can be backscattered by neighboring atoms. The quantum Interference of the Initial... 

Analytical electron microscopy (AEM) can use several signals from the specimen to analyze volumes of catalyst material about a thousand times smaller than conventional techniques. X-ray emission spectroscopy (XES) is the most quantitative mode of chemical analyse in the AEM and is now also useful as a high resolution elemental mapping technique. Electron energy loss spectroscopy (EELS) vftiile not as well developed for quantitative analysis gives additional chemical information in the fine structure of the elemental absorption edges. EELS avoids the problem of spurious x-rays generated from areas of the spectrum remote from the analysis area. 

For chemical speciation, X-ray absorption spectroscopy is another supreme tool taking advantage of its electronic and structural information power. Also, REMPI-MS is outstanding in its selectivity for molecular species. Radioanalytical methods have also been used for speciation analysis [548]. Microscopical speciation analysis requires SSIMS or LMMS [549]. 

The electronic structure of /nmv-[NiCl2(I I20)4]-21LO has been investigated in detail, both by calculations and by absorption and luminescence spectroscopy.1138... 

Mo2(02CCH2).. Metal compounds with multiple metal-metal bonds such as Mo2(02CCH3)4 of symmetry, have attracted much experimental and theoretical attention focussed on the description of bonding and bond strength (46-48). Their electronic structure has been investigated experimentally by various methods such as resonance Raman, photoelectron spectroscopy, ultraviolet absorption and polarization studies of the matrix isolated sample (49-56). 

For a review of absorption and emission spectroscopy of porphyrins and metalloporphyrins, see Gouterman, M. Optical spectra and electronic structure of porphyrins and related rings. In The Porphyrins Dolphin, D., Ed., Academic Press New York 1978, Vol. Ill, pp 1-165. 

The verification of the presence of hydrogen in the film has proved more controversial, primarily because many of the structural investigations have been carried out after the film has been dried in vacuo. An example of the problems here is the fact that electron diffraction, which has to be carried out in vacuo, reveals a relatively well-crystallised spinel lattice whose origin may be the comparatively high sample heating encountered in the electron beam. Moreover, the use of in situ techniques, such as Mossbauer and X-ray absorption spectroscopy, clearly reveals marked differences between the spectra of the films in situ and the spectra of the same films ex situ as well as the spectra of y-Fe203 and y-FeOOH standards. These differences are most naturally ascribed to hydration of the spinel forms. 

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