Electrons impinging or escaping from a solid surface undergo surface electronic
excitations which are competitive in nature to other electron-solid interaction channels. The detailed
information about electron inelastic scattering probability for surface excitations at solid surface is
also important in reflection electron energy loss spectroscopy. A self energy formalism based on
quantum mechanical treatment of interaction of electrons with a semi-infinite medium, which uses
the optical dielectric function is considered to study surface boundary effect for planar surfaces of
Cu and Ni for various conditions of electron-solid interactions. The total surface excitation
probability of an electron while crossing the surface boundary once is numerically computed by
integrating surface term of spatial and angular dependent differential inelastic cross sections over
energy loss and distance from the surface. It is found that surface effect is prominent for low energy
electrons and large oblique angles with respect to surface normal and confined to the close vicinity
of surface boundary.