Maximum depth of characteristic X-ray generation

Gaber, M.; Fitting, H.‐J.

doi:10.1002/pssa.2210900232

Cited by 3 publications

(1 citation statement)

References 11 publications

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“…In addition, only electrons with an energy above E c = 5 keV can excite photons used for imaging due to the PCXD’s detector threshold. Castaing or Gaber and Fitting define the maximum X-ray emission depth z m (in nm) for incoming electrons perpendicular to the object surface as [ 16 , 17 ]: d = (0.033 (E 0 1.7 − E c 1.7 ) A)/(ρZ), …”

Section: Resultsmentioning

confidence: 99%

Target Design in SEM-Based Nano-CT and Its Influence on X-ray Imaging

Fell,

Wetzler,

Maisl

et al. 2023

J. Imaging

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Nano-computed tomography (nano-CT) based on scanning electron microscopy (SEM) is utilized for multimodal material characterization in one instrument. Since SEM-based CT uses geometrical magnification, X-ray targets can be adapted without any further changes to the system. This allows for designing targets with varying geometry and chemical composition to influence the X-ray focal spot, intensity and energy distribution with the aim to enhance the image quality. In this paper, three different target geometries with a varying volume are presented: bulk, foil and needle target. Based on the analyzed electron beam properties and X-ray beam path, the influence of the different target designs on X-ray imaging is investigated. With the obtained information, three targets for different applications are recommended. A platinum (Pt) bulk target tilted by 25° as an optimal combination of high photon flux and spatial resolution is used for fast CT scans and the investigation of high-absorbing or large sample volumes. To image low-absorbing materials, e.g., polymers or organic materials, a target material with a characteristic line energy right above the detector energy threshold is recommended. In the case of the observed system, we used a 30° tilted chromium (Cr) target, leading to a higher image contrast. To reach a maximum spatial resolution of about 100 nm, we recommend a tungsten (W) needle target with a tip diameter of about 100 nm.

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Section: Resultsmentioning

confidence: 99%

Target Design in SEM-Based Nano-CT and Its Influence on X-ray Imaging

Fell,

Wetzler,

Maisl

et al. 2023

J. Imaging

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Mean depth of X‐ray production by electron beams in thick targets

Gaber

El-Khier

1990

X-Ray Spectrometry

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An analytical expression was deduced for calculating the mean depth of ionization, z, in electron probe x-ray microanalysis. The data used were generated from previous Monte Carlo calculations for bulk targets of aluminium, titanium, iron, copper, arsenic, indium, tungsten, gold and lead at normal electron incidence for energies ranging from 10 to 40 keV. The results show that the mean depth pZ depends on the back scattering coefficient, 7, the energy of the incident electron, Eo , the excitation energy of the target atoms, E c , and the target atomic number, 2. In the case of non-normal incidence, it is found that the ratio of the mean depth pZ(a) at an angle of incidence a to the mean depth z(0) at normal incidence varies linearly with cos a and depends only on the atomic number of the target material. The effect of the atomic number of the target on the ionization mean depth was also studied.

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Six laws of low-energy electron scattering in solids

Fitting

2004

Journal of Electron Spectroscopy and Related Phenomena

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Maximum depth of characteristic X-ray generation

Cited by 3 publications

References 11 publications

Target Design in SEM-Based Nano-CT and Its Influence on X-ray Imaging

Target Design in SEM-Based Nano-CT and Its Influence on X-ray Imaging

Mean depth of X‐ray production by electron beams in thick targets

Six laws of low-energy electron scattering in solids

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