Sample positioner and deflection energy analyzer for measurements of photofield emission

A sample positioner and an electron energy analyzer for studies of photofield emission have been designed and constructed. The sample positioner allows photofield emission from every facet of a field emitter to be measured under illumination at arbitrary angles of light incidence and polarization. The electrons emitted from a selected facet are decelerated to a kinetic energy E0 by a series of cylindrical lenses and introduced into either one of two energy analyzers. The deflection energy analyzer, formed from two identical 127° cylindrical analyzers, is used when high-energy resolution is required. The full width at half-maximum height of the resolution function of this analyzer is proportional to E0 down to a minimum kinetic energy which is less than 0.5 eV, and is given by ΔEFWHM=(0.0390±0.0006)E0. The throughput depends on E0 due to a combination of resolution and aperturing effects, and varies as E3/20. The signal-to-noise ratio of the analyzer is limited to 2×104 by inelastic scattering of electrons. The retardation energy analyzer is used for aligning the system and for measuring the energy-integrated current.