Atomic Beam Spin Echo. Principle and Surface Science Application

Abstract

We describe a novel technique, Atomic Beam Spin Echo (ABSE), which aims at measuring extremely small changes of the kinetic energy in a flux of atoms (or molecules) carrying a magnetic moment. In the last few decades, atomic and molecular beam techniques have contributed invaluable information to many areas of science [1]. Over the years, especially with the implementation of supersonic expansions, the quality of these beams has improved steadily, both in intensity and monochromaticity. Thusfar, the Time of Flight (TOF) method is the best established technique for studying dynamical process in, or with molecular beams. The energy resolution hereby is generally limited by the velocity spread in the beam. In addition, the need for a beam chopper and the fact that with TOF detection is time critical seriously limit the available intensity, so that at present, the TOF method seems to have reached a practicable resolution of some tenths of meV. In order to improve on this, we combine the in-beam Spin Echo (SE) method, originally developed for neutron scattering by Mezei [2], with helium atom scattering.