scholarly journals The Electronic Structure Signature of the Spin Cross-Over Transition of [Co(dpzca)2]

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Xin Zhang ◽  
Sai Mu ◽  
Yang Liu ◽  
Jian Luo ◽  
Jian Zhang ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Electronic Structure ◽  
Temperature Dependence ◽  
Absorption Spectroscopy ◽  
Spin State ◽  
Density Functional ◽  
Correlation Energy ◽  
High Spin State ◽  
X Ray ◽  
X Ray Absorption

Abstract The unoccupied electronic structure of the spin crossover molecule cobalt (II) N-(2-pyrazylcarbonyl)-2-pyrazinecarboxamide, [Co(dpzca)2] was investigated, using X-ray absorption spectroscopy (XAS) and compared with magnetometry (SQUID) measurements. The temperature dependence of the XAS and molecular magnetic susceptibility χmT are in general agreement for [Co(dpzca)2], and consistent with density functional theory (DFT). This agreement of magnetic susceptibility and X-ray absorption spectroscopy provides strong evidence that the changes in magnetic moment can be ascribed to changes in electronic structure. Calculations show the choice of Coulomb correlation energy U has a profound effect on the electronic structure of the low spin state, but has little influence on the electronic structure of the high spin state. In the temperature dependence of the XAS, there is also evidence of an X-ray induced excited state trapping for [Co(dpzca)2] at 15 K.

Electronic structure of S-nitrosothiols from sulfur K-edge X-ray absorption spectroscopy

2011 ◽  
Vol 89 (2) ◽  
pp. 93-97 ◽  
Author(s):  
Vlad Martin-Diaconescu ◽  
Inna Perepichka ◽  
D. Scott Bohle ◽  
Pierre Kennepohl
Keyword(s):  
Experimental Data ◽  
Electronic Structure ◽  
Absorption Spectroscopy ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Computational Models ◽  
Nitroso Group ◽  
X Ray ◽  
X Ray Absorption

Sulfur K-edge X-ray absorption spectroscopy (S K-edge XAS) was applied to investigate the electronic structure of primary and tertiary S-nitrosothiols. Our experimental data, supported by density functional calculations, indicate that changes at Cα affect the S-nitroso group through both inductive and direct orbital effects. Furthermore, our data are consistent with a weakening of the S–N bond in tertiary S-nitrosothiols as compared to their primary S-nitroso analogues. These results support existing computational models and suggest that the reactivity of S-nitrosothiols is not dominated by the electronics of the S–N bond.

Electronic structure and magnetic states inLa1−xSrxCoO3studied by photoemission and x-ray-absorption spectroscopy

1997 ◽  
Vol 56 (3) ◽  
pp. 1290-1295 ◽  
Author(s):  
T. Saitoh ◽  
T. Mizokawa ◽  
A. Fujimori ◽  
M. Abbate ◽  
Y. Takeda ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Absorption Spectroscopy ◽  
X Ray ◽  
Magnetic States ◽  
X Ray Absorption

X-ray absorption spectroscopy and density functional analysis of the Fe3+ distribution profile on Al sites in a chrysoberyl crystal, BeAl2O4:Fe3+

2016 ◽  
Vol 49 (2) ◽  
pp. 385-388 ◽  
Author(s):  
Kanokwan Kanchiang ◽  
Atipong Bootchanont ◽  
Janyaporn Witthayarat ◽  
Sittichain Pramchu ◽  
Panjawan Thanasuthipitak ◽  
...  
Keyword(s):  
Optical Properties ◽  
Absorption Spectroscopy ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Distribution Profile ◽  
Laser Applications ◽  
Edge Structure ◽  
X Ray ◽  
Site Distribution ◽  
X Ray Absorption

Chrysoberyl is one of the most interesting minerals for laser applications, widely used for medical purposes, as it exhibits higher laser performance than other materials. Although its utilization has been vastly expanded, the location of transition metal impurities, especially the iron that is responsible for chrysoberyl's special optical properties, is not completely understood. The full understanding and control of these optical properties necessitates knowledge of the precise location of the transition metals inside the structure. Therefore, synchrotron X-ray absorption spectroscopy (XAS), a local structural probe sensitive to the different local geometries, was employed in this work to determine the site occupation of the Fe3+ cation in the chrysoberyl structure. An Fe K-edge X-ray absorption near-edge structure (XANES) simulation was performed in combination with density functional theory calculations of Fe3+ cations located at different locations in the chrysoberyl structure. The simulated spectra were then qualitatively compared with the measured XANES features. The comparison indicates that Fe3+ is substituted on the two different Al2+ octahedral sites with the proportion 60% on the inversion site and 40% on the reflection site. The accurate site distribution of Fe3+ obtained from this work provides useful information on the doping process for improving the efficiency of chrysoberyl as a solid-state laser material.

Electronic, magnetic, vibrational, and X-ray spectroscopy of inverse full-Heusler Fe2IrSi alloy

2021 ◽  
Author(s):  
Lalrinkima ◽  
C. E. Ekuma ◽  
T. C. Chibueze ◽  
L. A. Fomin ◽  
I. V. Malikov ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectroscopy ◽  
Density Functional ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Absorption ◽  
Full Heusler

The electronic, magnetic, structural, vibrational, and X-ray absorption spectroscopy of inverse full-Heusler Fe2IrSi alloy has been studied from density functional theory (DFT). The XA-phase with FM-configuration is the most stable one, structurally and thermodynamically.

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