Electron inelastic mean free path for B4C and BC2N determined by reflection electron energy loss spectroscopy

In a previous paper it was shown that the influence of specimen thickness on quantitative electron energy loss spectroscopy (EELS) can be judged by measuring the intensity ratio of any two characteristic EEL edges as a function of thickness. If the specimen is homogeneous and thickness effects are neglegible then, one can show from Egerton’s formulation that this intensity ratio should be a constant. Any departure from a constant value indicates a breakdown of the quantitative theory due to thickness related effects. It was shown that if the ratio of Ip/IO (Ip = intensity of plasmon loss, IO = intensity of zero loss) exceeds ∼ 0.3 then quantitative analysis can be in significant error. In subsequent work Egerton showed that a better measure is the ratio of ℓn(It/IO) which is related to the ratio of t/λ. Here It is the total energy loss intensity, t the specimen thickness and λ the mean-free path for total inelastic scattering.

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Parameterization of the mean free path for inelastic scattering of fast electrons

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100125543 ◽

1987 ◽

Vol 45 ◽

pp. 122-123

Author(s):

R. F. Egerton ◽

S. C. Cheng ◽

T. Malis

Keyword(s):

Energy Loss ◽

Free Path ◽

Mean Free Path ◽

Fast Electrons ◽

Before And After ◽

The Mean ◽

Convergent Beam ◽

Inelastic Mean Free Path ◽

Electron Energy Loss ◽

Beam Diffraction

The areas, Iz and It, under the zero-loss peak and under the entire energy-loss spectrum (of a sample of thickness t) are related by the formula:t/ƛ(β) = ln (It/Iz) (1)where ƛ(β) is the inelastic mean free path for all energy losses and for scattering into the collection aperture, of semiangle β. We have used Eq.(l) to experimentally determine ƛ(β) by electron energy-loss spectroscopy of specimens of known composition and thickness. In the case of crystalline samples, the local thickness t was measured by convergent-beam diffraction. In the case of evaporated thin-film specimens, the average thickness was obtained by accurately weighing the substrate before and after deposition. The energy-loss spectroscopy was carried out in CTEM mode with incident energies Eo between 20keV and 120keV, and with collection semiangles in the range 0.2 mrad to 100 mrad.

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Intergalactic electromagnetic cascades in the magnetized Universe as a tool of astroparticle physics

EPJ Web of Conferences ◽

10.1051/epjconf/201819108009 ◽

2018 ◽

Vol 191 ◽

pp. 08009 ◽

Cited By ~ 2

Author(s):

Timur Dzhatdoev ◽

Emil Khalikov ◽

Anna Kircheva ◽

Egor Podlesnyi ◽

Anastasia Telegina

Keyword(s):

Magnetic Field ◽

Energy Loss ◽

Free Path ◽

Electron Energy ◽

Coherence Length ◽

Deflection Angle ◽

Mean Free Path ◽

Astroparticle Physics ◽

Electron Energy Loss

We review the physics of intergalactic electromagnetic cascades in the presence of the extragalactic magnetic field (EGMF). Various regimes of intergalactic electromagnetic cascades are considered depending on the number of cascade generations, the value of the cascade electron deflection angle, and the relations between the EGMF coherence length, typical cascade γ-ray mean free path, and electron energy loss length. We also review contemporary constraints on the EGMF parameters and explore the sensitivity of various γ-ray instruments to the EGMF parameters.

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