Abstract
The characteristic electron energy loss spectra of 1500 eV electrons scattered by aluminium-magnesium and aluminium-copper alloys have been measured. A plasma and a lowered plasma energy loss were observed in the alloys, and it was found that surface oxidation caused the disappearance of the lowered plasma loss and the appearance of a new modified lowered plasma loss. Though the compositions of the evaporated alloy specimens were unknown, the three energy losses were observed to vary continuously between the values observed for the three elements. This continuous change can be interpreted in terms of the changing free electron density in alloys of varying composition. It is concluded that measurements of the characteristic loss spectra of alloys can differentiate between losses due to individual and collective electron excitation.