A simple photoionization scheme for characterizing electron and ion spectrometers

We present a simple diode laser-based photoionization scheme for generating electrons and ions with well-defined spatial and energetic (<2 eV) structures. This scheme can easily be implemented into ion or electron imaging spectrometers for the purpose of off-line characterization and calibration. The low laser power ~1$ mW needed from a passively stabilized diode laser and the low flux of potassium atoms in an effusive beam make our scheme a versatile source of ions and electrons for applications in research and education.