Bolt-on source of spin-polarized electrons for inverse photoemission

We have developed a portable spin-polarized electron gun which can be bolted on to an ultrahigh vacuum chamber. The gun has been successfully operated with an electron gun to target distance of about 150 mm. This allows accommodation of other surface science equipment in the same vacuum system. The spin-polarized electrons are obtained via photoemission from a negative electron affinity GaAs(001) surface with circularly polarized light. A transversely polarized beam is achieved with a 90° electrostatic deflector. A set of two three-element electrostatic tube lenses are employed to transport and to focus the electrons onto a target. The measured transmission through the electron optics is ≫70% for electron energies in the range 7–20 eV. This is achieved by using large diameter electron transport lenses. The energy resolution of the electron beam is measured to be better than 0.27 eV and the polarization is determined to be 25±5%. © 1998 American Institute of Physics.