RBS: Introduction and principle

• The scattered E can be derived from the principles of conservation of energy and momentum, and is given by (in laboratory frame of reference):

• The multiplication factor k on the right hand side of the equation is often referred to as the kinematic factor, which is the ratio of the scattered alpha particle's energy to its incident energy gives a convenient method for determining the elemental make up of the target atoms in the sample. For M/m > 1, k is a slow-varying function of θ, having the maximum value of 1 at θ = 0 and the minimum value at θ = 180°. For M/m = 1, the value of k is zero beyond 90°. The plots of k versus θ and k versus E₀ are displayed below.

Figure 18.04: The plot of k versus θ for M/m = 0, 4, 20. k values depend strongly on the ratio between M/m.

Figure 18.05: The plot of k versus θ = 180°.