Electron beam irradiation penetration depth

As shown in Fig. 1, low energy electron beam irradiation hardened the treated surface layer to a indentation penetration depth of about 3 im. The electron-beam hardening decayed significantly with increasing penetration depth. Therefore, the hybrid surface reinforced specimen has a large gradient of hardness along the depth direction. However, the enhanced... 

Electron beam irradiation can be delivered faster than that of y-rays and can be carried out while the material is hot. Electron beam irradiation has limited penetration. A voltage of 3 MV delivered by the irradiator used in one study led to a penetration depth of only 1 cm. The procedure consists of irradiation of the material in the molten state, which is then roughly shaped into an acetabular component. This is followed by re-machining the final shape of the acetabular component [50, 51, 60-63]. 

As a generalisation, electron beam treatment creates similar effects to gamma irradiation, but usually on slightly reduced scale, since depth of penetration is less. 

In a comparison between electron beam and y-irradiation effects on amorphous antimony triselenide, El-Sayed (2004) irradiated thin films to equal doses of electron and y-radiation. He measured the change in the energy gap of the material and found that the electron beam affects the material more than the y-radiation. However, if he had used a bulk material, the conclusion may have been different, because of the long penetration depth of y-radiation through the bulk while the electron beam stops within small distance. 

The great troublesome problem in the electron beam (EB) irradiation is the depth of penetration [59], which depends not only by the incident particle energy, but also on the material density. This problem can be solved by double face irradiation, when exposure dose can be considered uniform along profundity [60]. The main problem in the selection of the type of accelerator is the nominal power, which must be rigorously correlated with its applications [61]. 

Fig. 1 shows the schematics of the experimental procedure. A quadratic point lattice of polymer in TS-6 monomer was generated by irradiation with 30 keV electrons in a scanning electron microscope (SEM). The electron beam diameter at the sample surface was about 5 nm however it increased inside the crystal by about one order of magnitude due to scattering. The penetration depth of 30 keV electrons is about 10 pm in this material. 

When incident light is the source of initiation energy, the abundance of chromophores with the appropriate absorption range influenees the rate of carbon-hydrogen cleavage. Naturally, the flux of the irradiation is important. When thick or pigmented samples are irradiated, the intensity of radiation may be attenuated as a function of depth, resulting in a reduction of the concentration of alkyl radicals the further the radiation has to penetrate. This is typically encountered in plasma or electron beam treatments. 

The X-ray depth dose distributions in a thick water absorber with large area beams are shown in Fig. 3. These distributions indicate that the attenuation is essentially exponential, and that the penetrating quality increases with the incident electron energy. Depth dose distributions for irradiating materials from opposite directions show the minimum dose in the middle of the material. The dose uniformity ratio (DUR), also known as the Dmax/Dmin dose ratio, increases with the thickness of the material, as shown in Fig. 4 (lower set of curves). For any thickness, the DUR decreases as the incident electron energy increases. 

XPS, also known as electron microscopy for chemical analysis, is a powerful tool for elemental detection, chemical state identification, and quantification of various atomic species at the surface (Devries, 1998 Fadley, 2010). XPS uses photoelectrons that are emitted after the absorption of X-rays (Fig. 5.6). In XPS, samples are irradiated with a monochromatic beam of X-rays with a known energy (usually Mg Ka (1253.5 eV) or A1 Ka (1486.6 eV)), which penetrates deeply into the sample the depth varies from micrometers to millimeters, resulting in the emission of electrons. Because electrons are readily absorbed, only the electrons emitted from the few top atomic layers escape the material and are detected. Consequently, the information depth of XPS is less than 10 nm, depending on the nature of the material under evaluation and the kinetic energy ( t) of the emitted electrons. The kinetic energy of the emitted electrons will be... 

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