Question

Which of the following is the energy after collision with a surface atom for a scattering angle of 90^o when Eo is the energy of the incident ion, M1 is the mass of the incident ion and M2 is the mass of the target surface?

(a) Eo(M2-M1)/(M2+M1)

(b) Eo(M2+M1)/(M2-M1)

(c) Eo(M2×M1)/(M2+M1)

(d) Eo(M2-M1)/(M2×M1)

Answer 1

Correct option is (a) Eo(M2-M1)/(M2+M1)

The best I can explain: Eo(M2-M1)/(M2+M1) is the energy after collision with a surface atom for a scattering angle of 90^o. But, this is valid only when M1<M2.