scholarly journals X-ray absorption linear dichroism at the Ti K-edge of rutile (001) TiO2 single crystal

2020 ◽  
Vol 27 (2) ◽  
pp. 425-435
Author(s):  
T. C. Rossi ◽  
D. Grolimund ◽  
O. Cannelli ◽  
G. F. Mancini ◽  
C. Bacellar ◽  
...  
Keyword(s):  
Energy Levels ◽  
Point Group ◽  
Linear Dichroism ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
Group A ◽  
Weak Transition ◽  
Octahedral Crystal Field ◽  
X Ray Absorption

X-ray absorption linear dichroism of rutile TiO2 at the Ti K-edge provides information about the electronic states involved in the pre-edge transitions. Here, linear dichroism with high energy resolution is analyzed in combination with ab initio finite difference method calculations and spherical tensor analysis. It provides an assignment of the three pre-edge peaks beyond the octahedral crystal field splitting approximation and estimates the spatial extension of the corresponding final states. It is then discussed for the first time the X-ray absorption (XAS) of pentacoordinated titanium atoms due to oxygen vacancies and it is found that, similarly to anatase TiO2, rutile is expected to exhibit a transition on the low-energy side of peak A3. Its apparent absence in the experiment is related to the degree of p–d orbital mixing which is small in rutile due to its centrosymmetric point group. A recent XAS linear dichroism study on anatase TiO2 single crystals has shown that peak A2 has an intrinsic origin and is due to a quadrupolar transition to the 3d energy levels. In rutile, due to its centrosymmetric point group, the corresponding peak A2 has a small dipole moment explaining the weak transition. The results are confronted with recent picosecond X-ray absorption spectroscopy on rutile TiO2 nanoparticles.

scholarly journals High-Energy-Resolution Fluorescence-Detected X-ray Absorption of the Q Intermediate of Soluble Methane Monooxygenase

2017 ◽  
Vol 139 (49) ◽  
pp. 18024-18033 ◽  
Author(s):  
Rebeca G. Castillo ◽  
Rahul Banerjee ◽  
Caleb J. Allpress ◽  
Gregory T. Rohde ◽  
Eckhard Bill ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Methane Monooxygenase ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
Soluble Methane Monooxygenase ◽  
X Ray Absorption

scholarly journals High-energy resolution X-ray absorption and emission spectroscopy reveals insight into unique selectivity of La-based nanoparticles for CO2

2015 ◽  
Vol 112 (52) ◽  
pp. 15803-15808 ◽  
Author(s):  
Ofer Hirsch ◽  
Kristina O. Kvashnina ◽  
Li Luo ◽  
Martin J. Süess ◽  
Pieter Glatzel ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Emission Spectroscopy ◽  
High Energy ◽  
Unit Cell ◽  
High Energy Resolution ◽  
Electron Configuration ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

The lanthanum-based materials, due to their layered structure and f-electron configuration, are relevant for electrochemical application. Particularly, La2O2CO3 shows a prominent chemoresistive response to CO2. However, surprisingly less is known about its atomic and electronic structure and electrochemically significant sites and therefore, its structure–functions relationships have yet to be established. Here we determine the position of the different constituents within the unit cell of monoclinic La2O2CO3 and use this information to interpret in situ high-energy resolution fluorescence-detected (HERFD) X-ray absorption near-edge structure (XANES) and valence-to-core X-ray emission spectroscopy (vtc XES). Compared with La(OH)3 or previously known hexagonal La2O2CO3 structures, La in the monoclinic unit cell has a much lower number of neighboring oxygen atoms, which is manifested in the whiteline broadening in XANES spectra. Such a superior sensitivity to subtle changes is given by HERFD method, which is essential for in situ studying of the interaction with CO2. Here, we study La2O2CO3-based sensors in real operando conditions at 250 °C in the presence of oxygen and water vapors. We identify that the distribution of unoccupied La d-states and occupied O p- and La d-states changes during CO2 chemoresistive sensing of La2O2CO3. The correlation between these spectroscopic findings with electrical resistance measurements leads to a more comprehensive understanding of the selective adsorption at La site and may enable the design of new materials for CO2 electrochemical applications.

A Johann-type X-ray emission spectrometer at the Rossendorf beamline

2016 ◽  
Vol 23 (3) ◽  
pp. 836-841 ◽  
Author(s):  
Kristina O. Kvashnina ◽  
Andreas C. Scheinost
Keyword(s):  
Atmospheric Pressure ◽  
Environmental Samples ◽  
Avalanche Photodiode ◽  
High Energy ◽  
European Synchrotron Radiation Facility ◽  
High Energy Resolution ◽  
X Ray ◽  
Bent Crystal ◽  
Crystal Analyzer ◽  
X Ray Absorption

This paper gives a detailed description, including equations, of the Johann-type X-ray emission spectrometer which has been recently installed and tested at the Rossendorf beamline (ROBL) of the European Synchrotron Radiation Facility. The spectrometer consists of a single spherically bent crystal analyzer and an avalanche photodiode detector positioned on the vertical Rowland cycle of 1 m diameter. The hard X-ray emission spectrometer (∼3.5–25 keV) operates at atmospheric pressure and covers the Bragg angles of 65°–89°. The instrument has been tested at high and intermediate incident energies,i.e.at the ZrK-edge and at the AuL3-edge, in the second experimental hutch of ROBL. The spectrometer is dedicated for studying actinides in materials and environmental samples by high-energy-resolution X-ray absorption and X-ray emission spectroscopies.

scholarly journals Wetting Induced Oxidation of Pt-based Nano Catalysts Revealed by In Situ High Energy Resolution X-ray Absorption Spectroscopy

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Yi-Tao Cui ◽  
Yoshihisa Harada ◽  
Hideharu Niwa ◽  
Tatsuya Hatanaka ◽  
Naoki Nakamura ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Energy Resolution ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
Nano Catalysts ◽  
X Ray Absorption

Time-resolved XAFS measurement using quick-scanning techniques at BSRF

2017 ◽  
Vol 24 (3) ◽  
pp. 674-678 ◽  
Author(s):  
Shengqi Chu ◽  
Lirong Zheng ◽  
Pengfei An ◽  
Hui Gong ◽  
Tiandou Hu ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
High Energy ◽  
High Energy Resolution ◽  
Double Crystal ◽  
Time Resolved ◽  
Edge Structure ◽  
X Ray ◽  
Double Crystal Monochromator ◽  
Good Signal ◽  
X Ray Absorption

A new quick-scanning X-ray absorption fine-structure (QXAFS) system has been established on beamline 1W1B at the Beijing Synchrotron Radiation Facility. As an independent device, the QXAFS system can be employed by other beamlines equipped with a double-crystal monochromator to carry out quick energy scans and data acquisition. Both continuous-scan and trapezoidal-scan modes are available in this system to satisfy the time scale from subsecond (in the X-ray absorption near-edge structure region) to 1 min. Here, the trapezoidal-scan method is presented as being complementary to the continuous-scan method, in order to maintain high energy resolution and good signal-to-noise ratio. The system is demonstrated to be very reliable and has been combined with in situ cells to carry out time-resolved XAFS studies.

scholarly journals High Energy Resolution Off-Resonant Spectroscopy for X-Ray Absorption Spectra Free of Self-Absorption Effects

2014 ◽  
Vol 112 (17) ◽  
Author(s):  
W. Błachucki ◽  
J. Szlachetko ◽  
J. Hoszowska ◽  
J.-Cl. Dousse ◽  
Y. Kayser ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Energy Resolution ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
X Ray Absorption
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