Multiple scattering, particle-substrat

ELNES on Si L ionisation edge can be used to reveal the change in coordination of Si atoms due to the reductive treatment. After background subtraction and removal of multiple scattering [49], the spectra from different areas for both samples are plotted in Fig. 5. Before reduction, the Si L ELNES from as-grown silica and from the area with Pt particles exhibit the typical Si L ELNES of Si02, identical with the one measured from the Si02 substrate after the treatment. Some new features appear in the Si L ELNES spectrum obtained from particle after the reduction. This is a... 

Due to the extremely short wavelengths of the accelerated electrons, the resolution of the instrument is not due to the radiation diffraction limits but to other effects such as multiple scattering of the electrons in the resist layer and substrate surface, and secondary electron emission [73,75,78]. These, mainly resist dependent, effects are hard to identify in detail but can be controlled to some extent during the exposure. However, it is not just the resolution of the resist which is the controlling factor in the ultimate particle size reached, rather it depends on exposure conditions (dose, beam intensity, etc.), the type of developer and processing technique used, and the way in which the hnal pattern is transferred to the substrate [79]. 

In general, the study of the scattered intensity by systems where multiple scattering is non-negligible is a difficult task. In order to resolve these difficulties we have used several approximations the particle size is assumed to be much smaller than the incident wavelength, so the Rayleigh dipole approximation is used to characterize the particle scattering. For the surface case, the perfect conductor approximation (PCA) ( = -go) for the substrate is applied. In both systems, the scattered field is calculated in the far-field approximation. For the purpose of this research, these approximations do not constitute serious restrictions and facilitate the numerical calculations. For real substrates (metallic or dielectric) and/or finite size particles, the main conclusions are unaffected [9]. The scattered intensity is calculated by means of the coupled dipole method (CDM) [10] for both the volume case and the surface case. In the latter, the PCA allows us to apply the image theory [11]. 

When the particles are on a substrate the fluctuations decrease and the relative errors are lower than when they are inside a volume. This is evidence of the weakening of multiple scattering due to the presence of the substrate. In... 

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