As positive projectile can be ionized or neutralized by interaction with the target, we should include the different charge states fractions of the protons to determine the doubly differential cross section (DDCS) for the secondary electron emission. A comparison of the double differential cross section using the Density Functional Theory (DFT) is presented. The energy loss of moving proton is also discussed with explicit inclusion of the different charge states and compared to the available experimental data in order to check the validity of the proposed model.