  It is found that for objects possessing small surface structures with
differing radii of curvature the secondary electron emission (SEE) yield may be
significantly higher than for objects with smooth surfaces of the same
material. The effect is highly pronounced for surface structures of nanometer
scale, often providing a more than 100% increase of the SEE yield. The results
also show that the SEE yield from surfaces with structure does not show an
universal dependence on the energy of the primary, incident electrons as it is
found for flat surfaces in experiments. We derive conditions for the
applicability of the conventional formulation of SEE using the simplifying
assumption of universal dependence. Our analysis provides a basis for studying
low-energy electron emission from nano structured surfaces under a penetrating
electron beam important in many technological applications.
