Third-generation conical spot profile analyzing low-energy electron diffraction

A newly designed conical spot profile analyzing low-energy electron diffraction (LEED) allows optimized access to the sample up to an angle of 45degrees with respect to the surface plane. This allows in vivo LEED measurements during deposition or adsorption. The electron optics of the electrostatic deflection unit and the newly designed entrance lens were simulated and optimized using an electron-beam ray-tracing algorithm. Different sample distances can be accommodated by adjusting the deflection voltage between the front and rear section. A new real-image SPA-LEED operation mode is presented allowing simple control of the instrument and accurate electron-beam positioning on the sample. (C) 2002 American Institute of Physics.