4. A 1000eV electron beam is directed toward a graphite (carbon) surface. The surface is contaminated with gold atoms, silver atoms and copper atoms (equal numbers of each type of metal atom). What will an energy spectrum of the electrons backscattered from this surface look like? The x-axis should be energy (EV)" with a range of 0 1200eV. The y axis should be number y of electrons. The energy, intensity and peak width of features seen in this spectrum are important. Label each peak in your rough sketch. (10 points) 1