Simulation of x-ray absorption near-edge spectra and x-ray fluorescence spectra of optically excited molecules

2006 ◽  
Vol 124 (9) ◽  
pp. 094106 ◽  
Author(s):  
R. K. Pandey ◽  
Shaul Mukamel
Keyword(s):  
Fluorescence Spectra ◽  
X Ray ◽  
Excited Molecules ◽  
X Ray Absorption

Si X-Ray Absorption Near Edge Structure(XANES) in X-Ray Fluorescence Spectra

1998 ◽  
Vol 27 (3) ◽  
pp. 245-246 ◽  
Author(s):  
Jun Kawai ◽  
Kouichi Hayashi ◽  
Kazuaki Okuda ◽  
Atsushi Nisawa
Keyword(s):  
Fluorescence Spectra ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Resolving Competing Conical Intersection Pathways: Time-Resolved X-ray Absorption Spectroscopy of trans-1,3-Butadiene

2021 ◽  
Author(s):  
Issaka Seidu ◽  
Simon Neville ◽  
Ryan J MacDonell ◽  
Michael S. Schuurman
Keyword(s):  
Absorption Spectroscopy ◽  
Conical Intersection ◽  
Theoretical Studies ◽  
Nuclear Dynamics ◽  
Time Resolved ◽  
X Ray ◽  
Excited Molecules ◽  
X Ray Absorption

Time-resolved X-ray absorption spectroscopy is emerging as a uniquely powerful tool to probe coupled electronic-nuclear dynamics in photo-excited molecules. Theoretical studies to date have established that time-resolved X-ray absorption spectroscopy...

scholarly journals X-ray absorption, refraction and resonant scattering tensors in selenated protein crystals: implications for data collection strategies in macromolecular crystallography

2005 ◽  
Vol 38 (1) ◽  
pp. 168-182 ◽  
Author(s):  
G. Bricogne ◽  
S. C. Capelli ◽  
G. Evans ◽  
A. Mitschler ◽  
P. Pattison ◽  
...  
Keyword(s):  
Fluorescence Spectra ◽  
Simple Procedure ◽  
Resonant Scattering ◽  
Macromolecular Crystallography ◽  
Polarized Fluorescence ◽  
Inhibitor Molecule ◽  
X Ray ◽  
Multi Wavelength ◽  
X Ray Absorption ◽  
Collection Strategies

Polarized fluorescence spectra were recorded in the vicinity of the Se and BrKedges on crystals of the selenated protein aldose reductase in complex with a brominated inhibitor molecule. The X-ray absorption, refraction and resonant scattering tensors as a function of X-ray energy were derived from these data. Substantial dichroism and anisotropy of resonant scattering were observed in these crystals. It is predicted that these effects are present in many resonant scattering experiments in macromolecular crystallography and are likely to affect the diffraction data. As a consequence, the anomalous phasing signal in single- or multi-wavelength anomalous diffraction experiments can be optimized simply by choosing a judicious orientation of the crystal with respect to the polarization direction of the incident X-ray beam. A simple procedure is presented to achieve this, prior to any knowledge about the selenium sites.

X-Ray absorption and photoionization of laser excited molecules

2003 ◽  
Vol 129 (1) ◽  
pp. 43-54 ◽  
Author(s):  
Timofei Privalov ◽  
Faris Gel’mukhanov ◽  
Hans Ågren
Keyword(s):  
X Ray ◽  
Excited Molecules ◽  
X Ray Absorption

Extended X-Ray Absorption Fine Structure (EXAFS) in X-ray Fluorescence Spectra

1997 ◽  
Vol 66 (11) ◽  
pp. 3337-3340 ◽  
Author(s):  
Jun Kawai ◽  
Kouichi Hayashi ◽  
Yasuhiro Awakura
Keyword(s):  
Fine Structure ◽  
Fluorescence Spectra ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

X-ray microanalysis of thin specimens in the transmission electron microscope at voltages up to 1000 Kv.

1978 ◽  
Vol 36 (1) ◽  
pp. 540-541
Author(s):  
G. Cliff ◽  
M.J. Nasir ◽  
G.W. Lorimer ◽  
N. Ridley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Present Series ◽  
Constant Independent ◽  
X Ray ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
X Ray Absorption

In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.

SIGMAL: A Program for Calculating L-Shell lonization Cross-Sections

1981 ◽  
Vol 39 ◽  
pp. 198-199 ◽  
Author(s):  
R.F. Egerton
Keyword(s):  
Cross Sections ◽  
Fortran Program ◽  
Absorption Data ◽  
X Ray ◽  
Atomic Electrons ◽  
Energy Dependent ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Shell Ionization

SIGMAL is a short (∼ 100-line) Fortran program designed to rapidly compute cross-sections for L-shell ionization, particularly the partial crosssections required in quantitative electron energy-loss microanalysis. The program is based on a hydrogenic model, the L1 and L23 subshells being represented by scaled Coulombic wave functions, which allows the generalized oscillator strength (GOS) to be expressed analytically. In this basic form, the model predicts too large a cross-section at energies near to the ionization edge (see Fig. 1), due mainly to the fact that the screening effect of the atomic electrons is assumed constant over the L-shell region. This can be remedied by applying an energy-dependent correction to the GOS or to the effective nuclear charge, resulting in much closer agreement with experimental X-ray absorption data and with more sophisticated calculations (see Fig. 1 ).

Raman And Fluorescence Spectra Observed in Laser Microprobe Measurements of Several Compositions in the Ln-Ba-Cu-O System

1990 ◽  
Vol 48 (2) ◽  
pp. 278-279
Author(s):  
Edgar S. Etz ◽  
Thomas D. Schroeder ◽  
Winnie Wong-Ng
Keyword(s):  
Fluorescence Spectra ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Raman Microprobe ◽  
Methods Of Synthesis ◽  
Compositional Homogeneity ◽  
Processing Techniques

We are investigating by Raman microprobe measurements the superconducting and related phases in the LnBa2Cu3O7-x (for x=0 to 1) system where yttrium has been replaced by several of the lanthanide (Ln = Nd,Sm,Eu,Ho,Er) elements. The aim is to relate the observed optical spectra (Raman and fluorescence) to the compositional and structural properties of these solids as part of comprehensive materials characterization. The results are correlated with the methods of synthesis, the processing techniques of these materials, and their superconducting properties. Of relevance is the substitutional chemistry of these isostructural systems, the differences in the spectra, and their microanalytical usefulness for the detection of impurity phases, and the assessment of compositional homogeneity. The Raman spectra of most of these compounds are well understood from accounts in the literature.The materials examined here are mostly ceramic powders prepared by conventional solid state reaction techniques. The bulk samples are of nominally single-phase composition as determined by x-ray diffraction.

point-Analysis Using the Extrapolation Method in the Analytical Electron microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 430-431
Author(s):  
Zenji Horita ◽  
Ryuzo Nishimachi ◽  
Takeshi Sano ◽  
Minoru Nemoto
Keyword(s):  
Electron Microscope ◽  
Extrapolation Method ◽  
X Ray ◽  
Absorption Correction ◽  
Point Analysis ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Data Points ◽  
Identical Composition ◽  
X Ray Absorption

Absorption correction is often required in quantitative x-ray microanalysis of thin specimens using the analytical electron microscope. For such correction, it is convenient to use the extrapolation method[l] because the thickness, density and mass absorption coefficient are not necessary in the method. The characteristic x-ray intensities measured for the analysis are only requirement for the absorption correction. However, to achieve extrapolation, it is imperative to obtain data points more than two at different thicknesses in the identical composition. Thus, the method encounters difficulty in analyzing a region equivalent to beam size or the specimen with uniform thickness. The purpose of this study is to modify the method so that extrapolation becomes feasible in such limited conditions. Applicability of the new form is examined by using a standard sample and then it is applied to quantification of phases in a Ni-Al-W ternary alloy.The earlier equation for the extrapolation method was formulated based on the facts that the magnitude of x-ray absorption increases with increasing thickness and that the intensity of a characteristic x-ray exhibiting negligible absorption in the specimen is used as a measure of thickness.

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