RBS spectrum from thick layers

In the case of thick sample, the target is divided into thin sublayers ( slabs ) as shown in Fig. 2.16. The calculation for backscattering is done from front and back side of each sublayer taking energy loss into account. 

Starting energy from back side E2 Energy at surface 2°  

Since each isotope of each element in sublayer is treated as a brick (dQ) of the brick (as 2.31) is given by 

Thus an RBS spectrum is an overlay of the depth profile of all individual atomic species present in the target material as shown in Fig. 2.17. 

To determine o E), we use mean energy approximation i.e., use (t E)) with (E) = El — IS.EI2 and mean cross-section is calculated using 

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