Non-Rutherford Cross-Sections

Figure 6 Comparison of RBS and EBS simulated dataforathin 100nm PMMA film on a silicon substrate. The beam was simulated at normal incidence and at 170° backscattering. At 1500keV, Rutherford scattering applies and the recoil spectrum is completely dominated by the silicon substrate and the PMMA cannot be detected, except by the absence of Si at the surface. At 3038 keV, a sharp resonance in the 0( He, He)0 cross section makes the experiment sensitive to the 0 in PMMA at the sample surface, whereas, at 4000 keV, the large non-Rutherford cross section for C( He, He)C can be exploited to highlight C. Simulations were carried out using SIMNRA version 5.0. ...

Fig. 2.12. Ratio of non-Rutherford to Rutherford cross-sections for C, N, O, and Si at different proton energies...

There is some disagreement in the literature as to the value of the (4He, H) elastic scattering cross section. Values differing by almost a factor of two have been reported, as reviewed by Paszti et al. (1986). The cross section is strongly non-Rutherford, but ab initio calculations have been reported that agree well with the trend of experimental data and could be used in simulation calculations (Tirira et al., 1990). The cross section for deuterium analysis has a resonance near a 4He+ energy of 2.15 MeV, which allows enhanced sensitivity. Detailed measurements of this cross section have been reported by Besenbacher et al. (1986). In practice, rather than calculate an experiment s calibration from first principles, calibration standards are usually used hydrogen-implanted silicon standard are the norm. 

Cox R P, Leavitt J A and McIntyre L C Jr 1995 Non-Rutherford elastic backscattering cross sections Handbook of Modern Ion Beam Materials Analysis ed J R Tesmerand M Nastasi (Pittsburgh, PA Materials Research Society) ch A7, p 481... 

A database of non-Rutherford scattering cross-sections of H, He, and several other light elements, is also included in the available computer simulation codes (listed at page 362) for RBS analysis. 

SIGMACALC Gubrich AF (1996) software for non-Rutherford elastic backscattering cross-sections http //www.ionbeamcentre.com/sigmacalc/... 

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