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Absorption Spectroscopy of Biological Specimens Near X-ray Absorption Edges of Constituent Elements
Ito, Atsushi,Shinohara, Kunio Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2
Absorption spectra of biological specimens in the soft X-ray region have been presented with special reference to the XANES (X-ray absorption Near Edge Structure) of constituent elements. Absorption spectrum in this wavelength region is characterized by the absorption edges from which elemental content could be derived. In addition, XANES has a characteristic profile for chemical environment around the element such as chemical bond. Using the specific absorption peak we can assign not only the chemical bond but also molecules having such a chemical bond. In the present paper, absorption spectrum of DNA was measured in the wavelength range from 1.5nm to 5nm. Spectrum of Chinese Hamster Ovary (CHO) cells was compared with the DNA spectrum. XANES were distinct at the K absorption edges of major elements, C, N and O. In the spectrum of the cells prominent peaks at the L absorption edge of minor element Ca were also detectable. XANES profiles in small local areas in a cell could also be measured in combination with X-ray microscopy. These give information about local chemical environment in a cell. XANES at the phosphorus K absorption edge in a human HeLa cell was successfully obtained corresponding to a sharp and intensive XANES peak of DNA.
( Yong Gyu Choi ),( Kee Ahn Lee ),( Kee Sun Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2007 METALS AND MATERIALS International Vol.13 No.4
The Nd L3-edge XANES spectra of Nd-added FINEMET type soft magnetic alloys were characterized. Meltspun amorphous metallic alloys with compositions of Fe73.5Si13.5B9Cu0.5Nb3Nd0.5 and Fe73.5Si13.5B9Nb3Nd1 were heat-treated at 850 K for various durations up to 1 h in order to induce crystallization of nanocrystalline phases inside the alloys. The introduction of small amounts of Nd to the FINEMET-type alloys resulted in enhanced crystallization temperatures. The structural evolution of Nd over time was inferred based on changes of the Nd L3-edge x-ray absorption near-edge structure spectra. When coexisting with Cu atoms, Nd atoms clustered at the early stage of heat treatment and generally remained unaltered over time. In the absence of Cu atoms, however, the neighboring atoms of Nd changed over time. Magnetic properties of the heat-treated samples were discussed in connection with such local structural changes occurring at Nd sites in addition to the typical role of Cu atoms in crystallization behaviors.
Analysis of Wide-gap Semiconductors with Superconducting XAFS Apparatus
Shiki, S.,Zen, N.,Matsubayashi, N.,Koike, M.,Ukibe, M.,Kitajima, Y.,Nagamachi, S.,Ohkubo, M. The Korean Superconductivity Society 2012 Progress in superconductivity Vol.14 No.2
Fluorescent yield X-ray absorption fine structure (XAFS) spectroscopy is useful for analyzing local structure of specific elements in matrices. We developed an XAFS apparatus with a 100-pixel superconducting tunnel junction (STJ) detector array with a high sensitivity and a high resolution for light-element dopants in wide-gap semiconductors. An STJ detector has a pixel size of $100{\mu}m$ square, and an asymmetric layer structure of Nb(300 nm)-Al(70 nm)/AlOx/Al(70 nm)-Nb(50 nm). The 100-pixel STJ array has an effective area of $1mm^2$. The XAFS apparatus with the STJ array detector was installed in BL-11A of High Energy Accelerator Research Organization, Photon Factory (KEK PF). Fluorescent X-ray spectrum for boron nitride showed that the average energy resolution of the 100-pixels is 12 eV in full width half maximum for the N-K line, and The C-K and N-K lines are separated without peak tail overlap. We analyzed the N dopant atoms implanted into 4H-SiC substrates at a dose of 300 ppm in a 200 nm-thick surface layer. From a comparison between measured X-ray Absorption Near Edge Structure (XANES) spectra and ab initio FEFF calculations, it has been revealed that the N atoms substitute for the C site of the SiC lattice.
Analysis of Wide-gap Semiconductors with Superconducting XAFS Apparatus
S. Shiki,N. Zen,M. Koike,M. Ukibe,Y. Kitajima,S. Nagamachi,M. Ohkubo,N. Matsubayashi 한국초전도학회 2012 Progress in superconductivity Vol.14 No.2
Fluorescent yield X-ray absorption fine structure (XAFS) spectroscopy is useful for analyzing local structure of specific elements in matrices. We developed an XAFS apparatus with a 100-pixel superconducting tunnel junction (STJ) detector array with a high sensitivity and a high resolution for light-element dopants in wide-gap semiconductors. An STJ detector has a pixel size of 100 μm square, and an asymmetric layer structure of Nb(300 nm)-Al(70 nm)/AlOx/Al(70 nm)-Nb(50 nm). The 100-pixel STJ array has an effective area of 1 mm2. The XAFS apparatus with the STJ array detector was installed in BL-11A of High Energy Accelerator Research Organization, Photon Factory (KEK PF). Fluorescent X-ray spectrum for boron nitride showed that the average energy resolution of the 100-pixels is 12 eV in full width half maximum for the N-K line, and The C-K and N-K lines are separated without peak tail overlap. We analyzed the N dopant atoms implanted into 4H-SiC substrates at a dose of 300 ppm in a 200 nm-thick surface layer. From a comparison between measured X-ray Absorption Near Edge Structure (XANES) spectra and ab initio FEFF calculations, it has been revealed that the N atoms substitute for the C site of the SiC lattice.