X‐ray standing waves as probes of surface structure: Incident beam energy effects

1995 ◽  
Vol 78 (4) ◽  
pp. 2311-2322 ◽  
Author(s):  
Stephan Kirchner ◽  
Jin Wang ◽  
Zhijian Yin ◽  
Martin Caffrey
Keyword(s):  
Surface Structure ◽  
Beam Energy ◽  
Standing Waves ◽  
Incident Beam ◽  
X Ray ◽  
Incident Beam Energy

Low Beam Energy X-Ray Micro Analysis: How Useful Is It?

1997 ◽  
Vol 3 (S2) ◽  
pp. 881-882 ◽  
Author(s):  
Dale E. Newbury
Keyword(s):  
Electron Beam ◽  
Beam Energy ◽  
Strong Dependence ◽  
Incident Beam ◽  
X Ray ◽  
Upper Limit ◽  
History Of ◽  
Incident Beam Energy ◽  
Micro Analysis ◽  
Electron Range

Throughout the history of electron-beam X-ray microanalysis, analysts have made good use of the strong dependence of electron range on incident energy (R ≈ E1,7) to optimize the analytical volume when attacking certain types of problems, such as inclusions in a matrix or layered specimens. The “conventional” energy range for quantitative electron beam X-ray microanalysis can be thought of as beginning at 10 keV and extending to the upper limit of the accelerating potential, typically 30 - 50 keV depending on the instrument. The lower limit of 10 keV is selected because this is the lowest incident beam energy for which there is a satisfactory analytical X-ray peak excited from the K-, L-, or M- shells (in a few cases, two shells are simultaneously excited, e.g., Fe-K and Fe-L) for every element in the Periodic Table that is accessible to X-ray spectrometry, beginning with Be (Ek =116 eV) and extending to the transuranic elements. This criterion is based upon establishing a minimum overvoltage U = E0/Ec > 1.25, which is the practical minimum for useful excitation.

Some Advantages of EDS Analysis in a 400 KV Electron Microscope

1985 ◽  
Vol 62 ◽  
Author(s):  
S. Suzuki ◽  
T. Honda ◽  
Y. Bando
Keyword(s):  
Electron Microscope ◽  
Spatial Resolution ◽  
Beam Energy ◽  
Incident Beam ◽  
X Ray ◽  
Voltage Electron ◽  
Eds Analysis ◽  
High Voltage Electron Microscope ◽  
Incident Beam Energy ◽  
Better Than

ABSTRACTThe dependence of the characteristic and bremsstrahlung X-ray counts, the peak to background (P/B) ratio and the spatial resolution on the incident beam energy between 100 keV and 400 keV were measured using a high voltage electron microscope (HVEM). The bremsstrahlung count decreases much faster than that of the characteristic count with the increase of the incident beam energy. The decrease rate depends on Z number. It is ascertained that the P/B ratio and the spatial resolution at 400 keV were 2 or 3 and 2.5 times better than those at 100 keV, respectively.

Basic literacy in electron-probe x-ray microanalysis with energy-dispersive x-ray spectrometry: Qualitative and quantitative analysis

1994 ◽  
Vol 52 ◽  
pp. 384-385
Author(s):  
Dale E. Newbury
Keyword(s):  
Quantitative Analysis ◽  
Qualitative Analysis ◽  
Electron Probe ◽  
Beam Energy ◽  
Incident Beam ◽  
Energy Dispersive ◽  
Photon Detection ◽  
X Ray ◽  
Entire Energy Range ◽  
Incident Beam Energy

Rigorous electron probe x-ray microanalysis (EPMA) with energy dispersive x-ray spectrometry (EDS) takes place in two sequential steps: qualitative analysis followed by quantitative analysis.Qualitative analysis: Qualitative analysis involves the assignment of the peaks found in the x-ray spectrum to specific elements. One of the most important attributes of energy dispersive x-ray spectrometry (EDS) for qualitative analysis is that we can always view the complete x-ray spectrum. The EDS photon detection process effectively provides parallel detection in energy. Depending on the detector window and spectrometer characteristics, the entire energy range from Be K radiation (0.106 keV) to the incident beam energy can be available for analysis. With an incident beam energy of 15 keV, at least one family of x-ray lines (K, L, or M shell) will be excited for each element in the Periodic Table with atomic number ≥ 4. We ignore at our peril this capability to do a complete qualitative analysis at all specimen locations that we choose to measure. Quantitative analysis is meaningless if qualitative analysis has not been properly perfonned first. The bases for qualitative analysis include the exact energy of the peak(s), which places a premium on spectrometer calibration, the recognition of all members of each x-ray family and the possibility of two (or more) families being excited, the relative intensities ("weights of lines") within a family, and the artifacts associated with each high intensity peak, particularly the escape peak(s) and sum peak(s).

Optimizing conditions for x-ray microchemical analysis in analytical electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 548-549 ◽  
Author(s):  
N. J. Zaluzec
Keyword(s):  
Solid Angle ◽  
Analytical Electron Microscopy ◽  
Incident Beam ◽  
Thin Foil ◽  
Experimental Conditions ◽  
X Ray ◽  
Microchemical Analysis ◽  
Analytical Electron ◽  
Image Position ◽  
Incident Beam Energy

The ultimate sensitivity of microchemical analysis using x-ray emission rests in selecting those experimental conditions which will maximize the measured peak-to-background (P/B) ratio. This paper presents the results of calculations aimed at determining the influence of incident beam energy, detector/specimen geometry and specimen composition on the P/B ratio for ideally thin samples (i.e., the effects of scattering and absorption are considered negligible). As such it is assumed that the complications resulting from system peaks, bremsstrahlung fluorescence, electron tails and specimen contamination have been eliminated and that one needs only to consider the physics of the generation/emission process.The number of characteristic x-ray photons (Ip) emitted from a thin foil of thickness dt into the solid angle dΩ is given by the well-known equation

Inference on fission timescale from neutron multiplicity measurement in18O+184W

2022 ◽  
Author(s):  
Niraj Kumar Rai ◽  
Aman Gandhi ◽  
M T Senthil Kannan ◽  
Sujan Kumar Roy ◽  
Saneesh Nedumbally ◽  
...  
Keyword(s):  
Excitation Energy ◽  
Beam Energy ◽  
Incident Beam ◽  
Fission Process ◽  
Incident Beam Energy ◽  
Neutron Evaporation ◽  
Neutron Multiplicities ◽  
Nuclear Dissipation ◽  
Fission Yields ◽  
Primary Compound

Abstract The pre-scission and post-scission neutron multiplicities are measured for the 18O + 184W reaction in the excitation energy range of 67.23−76.37 MeV. Langevin dynamical calculations are performed to infer the energy dependence of fission decay time in compliance with the measured neutron multiplicities. Different models for nuclear dissipation are employed for this purpose. Fission process is usually expected to be faster at a higher beam energy. However, we found an enhancement in the average fission time as the incident beam energy increases. It happens because a higher excitation energy helps more neutrons to evaporate that eventually stabilizes the system against fission. The competition between fission and neutron evaporation delicately depends on the available excitation energy and it is explained here with the help of the partial fission yields contributed by the different isotopes of the primary compound nucleus.

Surface structure determination using x-ray standing waves

2005 ◽  
Vol 68 (4) ◽  
pp. 743-798 ◽  
Author(s):  
D P Woodruff
Keyword(s):  
Surface Structure ◽  
Structure Determination ◽  
Standing Waves ◽  
X Ray

The (3He,d) Reaction on 69Ga

1975 ◽  
Vol 53 (2) ◽  
pp. 117-122 ◽  
Author(s):  
J. P. Labrie ◽  
E. E. Habib ◽  
Z. Preibisz
Keyword(s):  
Born Approximation ◽  
Beam Energy ◽  
Incident Beam ◽  
Angular Distributions ◽  
Distorted Wave ◽  
Distorted Wave Born Approximation ◽  
Model Calculations ◽  
Sum Rule ◽  
Pairing Model ◽  
Incident Beam Energy

Excited levels of 70Ge and proton holes in 69Ga have been investigated by means of the 69Ga (3He, d)70Ge reaction at an incident beam energy of 22.5 MeV. Angular distributions were measured and are compared with the prediction of the distorted-wave-Born-approximation (DWBA) theory in order to obtain the spectroscopic strengths of each level.The number of proton holes in 69Ga was obtained from the sum rule of the spectroscopic strengths. The vacancy probability UJ2 and the center of gravity energy EJ for the 2p3/2, 1f5/2, and 2p1/2 subshells are[Formula: see text]These are compared with the pairing model calculations.

Surface Structure Analysis with X-ray Standing Waves

1991 ◽  
Vol T39 ◽  
pp. 328-332 ◽  
Author(s):  
J Zegenhagen
Keyword(s):  
Surface Structure ◽  
Structure Analysis ◽  
Standing Waves ◽  
X Ray

η AND η′ PHOTOPRODUCTION OFF THE NUCLEON

2005 ◽  
Vol 20 (02n03) ◽  
pp. 690-692 ◽  
Author(s):  
◽  
MARTIN KOTULLA
Keyword(s):  
Beam Energy ◽  
Incident Beam ◽  
Resonance Contribution ◽  
Preliminary Results ◽  
Data Basis ◽  
Incident Beam Energy

We have measured the reaction γp→η′p from threshold up to 2.6 GeV incident beam energy using the Crystal Barrel and TAPS detectors at the ELSA accelerator. At present the knowledge about the resonance contribution to this process is very limited. Our measurement is a significant improvement of the data basis. We will present preliminary results.

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