Elemental Analysis of thin Films Using Inner Shell Electron Energy Losses

The use of electron energy loss spectroscopy (ELS) for elemental analysis of thin films holds considerable promise. This technique has definite advantages in comparison with energy dispersive X-ray spectroscopy (EDS) for two fundamental reasons. First, the detection sensitivity is independent of the fluorescence yield, since for each inner shell excitation an energy loss electron exists as opposed to only a finite probability that an excitation will result in a X-ray emitted. Second, the information carrying energy loss electrons are contained in a small solid angle about 0° scattering angle as opposed to the resulting X-rays which are emitted uniformly over 4Π steradians. This means that a large fraction of the energy loss electrons can be detected (up to ∼90%) compared to only a small fraction (∼1%) of the emitted X-rays with an EDS system.