electron spectrometer
英[iˈlektrɔn spekˈtrɔmitə]美[ɪˈlɛkˌtrɑn spɛkˈtrɑmɪtɚ]
In an Electron spectrometer, an incoming beam of electrons is bent with electric or magnetic fields. As higher energy electrons will be bent less by the beam, this produces a spatially distributed range of energies.