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31.
T. Ruckert W. Keune W. Sturhahn M.Y. Hu J.P. Sutter T.S. Toellner E.E. Alp 《Hyperfine Interactions》2000,126(1-4):363-366
Incoherent nuclear resonant absorption of synchrotron radiation at the 14.413 keV nuclear resonance of 57Fe was employed to measure directly the Fe-projected (partial) phonon density of states (DOS) in epitaxial FeCr(0 0 1) superlattices
and in an 57Fe0.03Cr0.97(0 0 1) alloy film MBE-grown on MgO(0 0 1). The measurements were performed at 300 K with 2.3 meV energy resolution around
14.413 keV. At the interfaces, longitudinal vibrations of Fe atoms are suppressed, and a strong resonance phonon mode appears
near 23 meV.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
32.
Lili Gao Bin Chen Michael Lerche Esen E. Alp Wolfgang Sturhahn Jiyong Zhao Hasan Yava? Jie Li 《Journal of synchrotron radiation》2009,16(6):714-722
The applications of nuclear resonant scattering in laser‐heated diamond anvil cells have provided an important probe for the magnetic and vibrational properties of 57Fe‐bearing materials under high pressure and high temperature. Synchrotron X‐ray diffraction is one of the most powerful tools for studying phase stability and equation of state over a wide range of pressure and temperature conditions. Recently an experimental capability has been developed for simultaneous nuclear resonant scattering and X‐ray diffraction measurements using synchrotron radiation. Here the application of this method to determine the sound velocities of compressed Fe3C is shown. The X‐ray diffraction measurements allow detection of microscale impurities, phase transitions and chemical reactions upon compression or heating. They also provide information on sample pressure, grain size distribution and unit cell volume. By combining the Debye velocity extracted from the nuclear resonant inelastic X‐ray scattering measurements and the structure, density and elasticity data from the X‐ray diffraction measurements simultaneously obtained, more accurate sound velocity data can be derived. Our results on few‐crystal and powder samples indicate strong anisotropy in the sound velocities of Fe3C under ambient conditions. 相似文献
33.
Xiao Y Fisher K Smith MC Newton WE Case DA George SJ Wang H Sturhahn W Alp EE Zhao J Yoda Y Cramer SP 《Journal of the American Chemical Society》2006,128(23):7608-7612
Nitrogenase catalyzes a reaction critical for life, the reduction of N(2) to 2NH(3), yet we still know relatively little about its catalytic mechanism. We have used the synchrotron technique of (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to study the dynamics of the Fe-S clusters in this enzyme. The catalytic site FeMo-cofactor exhibits a strong signal near 190 cm(-)(1), where conventional Fe-S clusters have weak NRVS. This intensity is ascribed to cluster breathing modes whose frequency is raised by an interstitial atom. A variety of Fe-S stretching modes are also observed between 250 and 400 cm(-)(1). This work is the first spectroscopic information about the vibrational modes of the intact nitrogenase FeMo-cofactor and P-cluster. 相似文献
34.
Hu C Barabanschikov A Ellison MK Zhao J Alp EE Sturhahn W Zgierski MZ Sage JT Scheidt WR 《Inorganic chemistry》2012,51(3):1359-1370
Nuclear resonance vibrational spectra have been obtained for six five-coordinate imidazole-ligated iron(II) porphyrinates, [Fe(Por)(L)] (Por = tetraphenylporphyrinate, octaethylporphyrinate, tetratolylporphyrinate, or protoporphyrinate IX and L = 2-methylimidazole or 1,2-dimethylimidazole). Measurements have been made on both powder and oriented crystal samples. The spectra are dominated by strong signals around 200-300 cm(-1). Although the in-plane and out-of-plane vibrations are seriously overlapped, oriented crystal spectra allow their deconvolution. Thus, oriented crystal experimental data, along with density functional theory (DFT) calculations, enable the assignment of key vibrations in the spectra. Molecular dynamics are also discussed. The nature of the Fe-N(Im) vibrations has been elaborated further than was possible from resonance Raman studies. Our study suggests that the Fe motions are coupled with the porphyrin core and peripheral groups motions. Both peripheral groups and their conformations have significant influence on the vibrational spectra (position and shape). 相似文献
35.
Bekzat ABDIKADYR Alp KILI Onur ALEV Serkan BÜYÜKK
SE Zafer Ziya
ZTÜRK 《Turkish Journal of Chemistry》2021,45(2):295
Pristine and WO3 decorated TiO2 nanorods (NRs) were synthesised to investigate n-n-type heterojunction gas sensing properties. TiO2 NRs were fabricated via hydrothermal method on fluorine-doped tin oxide coated glass (FTO) substrates. Then, tungsten was sputtered on the TiO2 NRs and thermally oxidised to obtain WO3 nanoparticles. The heterostructure was characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. Fabricated sensor devices were exposed to VOCs such as toluene, xylene, acetone and ethanol, and humidity at different operation temperatures. Experimental results demonstrated that the heterostructure has better sensor response toward ethanol at 200 °C. Enhanced sensing properties are attributed to the heterojunction formation by decorating TiO2 NRs with WO3. 相似文献
36.
37.
The novel (E,E)-dioxime 5,6:13,14-dibenzo-9,10-benzo(15-crown-5)-2,3-bis(hydroxyimino)-7,12-dioxo-1,4,8,11-tetraazacyclotetradecane (H2L) has been synthesized by the reaction of 4′,5′-diaminobenzo(15-crown-5) with N,N′-bis(2-carbomethoxyphenyl)diaminoglyoxime (1). Only mononuclear CoIII and RuII complexes with a metal/ligand ratio of 1:2 have been isolated. The cobalt(III) complex bridged with BF2+ is achieved with H-bonded cobalt(III) complex and borontrifluoride ethyl ether complex. The reaction of BF2 bridged cobalt(III) complex with bis(benzonitril)palladium(II) chloride gives a trinuclear complex. The structures of dioxime and its complexes are proposed according to elemental analyses, 1H and 13C-NMR, IR and mass spectral data. 相似文献
38.
Dipl.-Phys. Lena Scherthan Rouven F. Pfleger Dr. Hendrik Auerbach Dipl.-Phys. Tim Hochdörffer Dr. Juliusz A. Wolny Dr. Wenli Bi Dr. Jiyong Zhao Dr. Michael Y. Hu Dr. E. Ercan Alp Dr. Christopher E. Anson Prof. Rolf Diller Prof. Annie K. Powell Prof. Volker Schünemann 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):8902-8907
39.
Özge Dağlı Dursun Ali Köse Gülçin Alp Avcı Onur Şahin 《Journal of Thermal Analysis and Calorimetry》2017,129(3):1389-1402
Coordination complexes of transition metal cations (CoII, NiII, CuII and ZnII) containing coumarilate and N,N′-diethylnicotinamide were synthesized. The structural characterization and thermal behaviour analysis of novel samples synthesized were conducted through elemental analysis, magnetic susceptibility, solid-state UV–Vis, direct and injection probe mass spectra, FTIR spectra, thermoanalytic TG-DTG/DTA and single crystal X-ray diffraction methods. The structural details of single crystals of [Co(dena)2(H2O)4](coum)2 (I) and [Cu(coum)2(dena)2(H2O)2] (III) complexes were resolved completely. Moreover, the results of analysis obtained for [Ni(coum)2(dena)2(H2O)2] (II) and [Zn(dena)2(H2O)4](coum)2 (IV) complexes were interpreted considering the samples with crystal structures defined and made assumptions about the structural details. It was determined that the complex of CoII metal cation has salt-type structure and the coordination number of metal is accomplished to six as the sum of 4 mol of water and also 2 mol of N,N′-diethylnicotinamide ligands in trans position located within the coordination sphere. It was observed that 2 mol of coumarilate anions are located outside the coordination sphere and have stabilized to the charge (2+) of metal. The CuII complex has totally molecular structure, and the coordination sphere of metal cation was 6 as the sum of 2 mol of water, 2 mol of N,N′-diethylnicotinamide and 2 mol of monoanionic monodentate coumarilate ligands. All ligands have been located in –trans position. The geometry of both complex structures is distorted octahedral. It is assumed that the NiII complex structure is isostructural with CuII complex structure and also does ZnII complex with CoII structure. It was determined that the decomposition products obtained from thermal analysis are the oxides of related metal cations. 相似文献
40.
Xiao Y Wang H George SJ Smith MC Adams MW Jenney FE Sturhahn W Alp EE Zhao J Yoda Y Dey A Solomon EI Cramer SP 《Journal of the American Chemical Society》2005,127(42):14596-14606
We have used (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to study the Fe(S(cys))(4) site in reduced and oxidized rubredoxin (Rd) from Pyrococcus furiosus (Pf). The oxidized form has also been investigated by resonance Raman spectroscopy. In the oxidized Rd NRVS, strong asymmetric Fe-S stretching modes are observed between 355 and 375 cm(-1); upon reduction these modes shift to 300-320 cm(-1). This is the first observation of Fe-S stretching modes in a reduced Rd. The peak in S-Fe-S bend mode intensity is at approximately 150 cm(-1) for the oxidized protein and only slightly lower in the reduced case. A third band occurs near 70 cm(-1) for both samples; this is assigned primarily as a collective motion of entire cysteine residues with respect to the central Fe. The (57)Fe partial vibrational density of states (PVDOS) were interpreted by normal mode analysis with optimization of Urey-Bradley force fields. The three main bands were qualitatively reproduced using a D(2)(d) Fe(SC)(4) model. A C(1) Fe(SCC)(4) model based on crystallographic coordinates was then used to simulate the splitting of the asymmetric stretching band into at least 3 components. Finally, a model employing complete cysteines and 2 additional neighboring atoms was used to reproduce the detailed structure of the PVDOS in the Fe-S stretch region. These results confirm the delocalization of the dynamic properties of the redox-active Fe site. Depending on the molecular model employed, the force constant K(Fe-S) for Fe-S stretching modes ranged from 1.24 to 1.32 mdyn/A. K(Fe-S) is clearly diminished in reduced Rd; values from approximately 0.89 to 1.00 mdyn/A were derived from different models. In contrast, in the final models the force constants for S-Fe-S bending motion, H(S-Fe-S), were 0.18 mdyn/A for oxidized Rd and 0.15 mdyn/A for reduced Rd. The NRVS technique demonstrates great promise for the observation and quantitative interpretation of the dynamical properties of Fe-S proteins. 相似文献