Which of the following is the energy after collision with a surface atom for a scattering angle of 90o 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)