X rays spectroscopy and

The combined use of energy-dispersive X-ray spectroscopy and TEM/STEM is a routine method of analytical electron microscopy enabling both qualitative and quantitative chemical analysis of interfaces and interlayers with high lateral resolution. Reso-... 

The rest of the conference was dominated by the recent discovery of Friedrich, Knipping, and Laue19 of the diffraction of X-rays in crystals and reviews of the first steps in X-ray spectroscopy and in the investigation of crystal properties. 

A Papua New Guinea sponge, Pseudoceratina sp., contains the unusual alkaloids ceratamines A (1142) and B (1143), and a biogenesis involving histidine and tyrosine is proposed (1173). The fermentation broth from Aspergillus fischeri var. thermomutatus has yielded CJ-12662 (1144) and UK-88051 (1145) (1174). The former metabolite was confirmed by X-ray spectroscopy and partial synthesis. A marine-derived Streptomyces sp. produces the novel pyrrolizidine 5-chlorobohem-amine C (1146), which was shown not to be an isolation artifact (1175). The Chinese medicinal plant Huperzia serrata has furnished 2-chlorohyperzine E (1147) (1176). 

Myneni, S. C. B. (2002). Soft X-ray spectroscopy and spectromicroscopy studies of organic molecules in the environment. In Applications of Synchrotron Radiation in Low-Temperature Geochemistry and Environmental Sciences, Fenter, R, Rivers, M., Sturchio, N, and Sutton, S., eds., Rev. Mineralogy Geochem. 49,485-579. 

Effects of Chemical Purity. Zirconia tubes from five different sources were analyzed at Pennsylvania State University using scanning electron microscopy, plasma emission spectroscopy, energy dispersive X-ray spectroscopy, and electron beam microprobe analysis. The sources for the tubes included several commercially available tubes as well as tubes fabricated by the Pennsylvania State University Ceramics Department. 

A similar borderline system, fran -bis[2-(2-chloroethyl)pyridine]palladium chloride (1), has been prepared and structurally characterized by X-ray spectroscopy and computational study.2 A study on the elimination reaction of (1) induced by quinuclidine in acetonitrile has been performed (Scheme 1). The results suggest that the initial product of elimination is a palladium complex of vinylpyridine and that displacement from this complex is partially rate determining in the formation of the uncoordinated product. Despite experimental efforts, it was not possible to distinguish between two possible mechanisms, E2 concerted or ElcB. 

We have investigated peptides whose structures were known beforehand from NMR or x-ray spectroscopy and related these structures to 2D-IR spectroscopy. Ultimately, one would like to deduce the structure of an unknown sample from a 2D-IR spectrum. In the case of 2D NMR spectroscopy, two different phenomena are actually needed to determine peptide structures. Essentially, correlation spectroscopy (COSY) is utilized in a first step to assign protons that are adjacent in the chemical structure of the peptide so that J coupling gives rise to cross peaks in these 2D spectra. However, this through-bond effect cannot be directly related to the three-dimensional structure of the sample, since that would require quantum chemistry calculations, which presently cannot be performed with sufficient accuracy. The nuclear Overhauser effect (NOE), which is an incoherent population transfer process and has a simple distance dependence, is used as an additional piece of information in order to measure the distance in... 

Urch, D. S. (1985). X-ray spectroscopy and chemical bonding in minerals. In Chemical Bonding and Spectroscopy in Mineral Chemistry (F. J. Berry and D. J. Vaughan, eds.) London Chapman and Hall. 

Figure 2.50. Structure of MgH2 proposed on the basis of X-ray spectroscopy and quantum chemical calculations (see text). The larger atoms are Mg, and the smaller ones are hydrogen.

Ostrom H, Fohlisch A, Nyberg M, Weinelt M, Heske C, Pettersson LGM, Nilsson A (2004) Ethylene on Cu(l 10) and Ni(l 10) Electronic structure and bonding derived from X-ray spectroscopy and theory. Surf Sci 559 85... 

Bain, D.C., McHardy, W.J. Lachowski, E.E. (1994) X-ray spectroscopy and microanalysis. In Wilson M.J (Ed.) Clay Mineralogy Spectroscopic and Chemical Determinative Methods. London Chapman and Hall, pp. 260-299. 

X-ray spectroscopy and photoelectron spectroscopy are two different methods for the analysis of electron distributions in solids. Each of them brings complementary information and possesses distinctive characteristics. Three points can be emphasized. 

Oxides. TijOa has been investigated by X-ray spectroscopy and by e.p.r. spectroscopy and magnetic susceptibility measurements - there has been an improved MO calculation of its band structure. A band model has been proposed to account for the origin of the magnetic moment and metallic transition of vanadium-doped Ti203- According to e.p.r. measurements the Ti ions in mixed valence phases of the system Ti 0 mined. 

Tonner BP, Droubay T, Denlinger J, Meyer-Ilse W, Warwick T, Rothe J, needier E, Pecher K, Nealson K, Gmndl T (1999) Soft X-ray spectroscopy and imaging of interfadal chemistry in environmental... 

Soft X-ray Spectroscopy and Spectromicroscopy Studies of Organic Molecules in the Environment... 

Soft X-ray spectroscopy and spectromicroscopy methods can provide high-resolution spectral and spatial information on the functional group chemistry and aggregate structures of organic molecules in aqueous solutions and on particle surfaces. The detection limits are around a few mM for C, N, and functional groups, and about 0.5 mM for the P, S and Cl functional groups. Development of better detection schemes for spectroscopy and spectromicroscopy techniques would allow the examination of molecules at much lower concentrations, and in a variety of samples. 

Satish . B. Myneni (PhD, Ohio State University) is an Assistant Professor in the Department of Geosciences at Princeton University and is also affiliated with the Departments of Chemistry and Civil and Environmental Engineering. He conducts his research activities at the Lawrence Berkeley National Laboratory where he is a Faculty Scientist. He earlier worked in the Berkeley Lab as a post-doctoral researcher and as Geological Scientist and developed soft X-ray spectroscopy and spectromicroscopy methods for examining light elements in aqueous solutions and on surfaces. His research interests are to explore ion solvation and complexation, and the chemistry of natural organic molecules at environmental interfaces. 

---