Molecular and Ultrafast Science Seminar (MUSS)

Spin manipulated molecular beams and their application as ultra sensitive surface probes

by Gil Alexandrowicz

Room 456 (DESY Hamburg)

Room 456

DESY Hamburg

Building 25f
Two different research activities will be briefly reviewed in this talk, both of which involve nuclear spin manipulation of low-energy particle beams. One activity is using the helium spin echo (HSE) technique to study surface dynamics. In the HSE experiment, a beam of helium-3 is used to perform an inelastic scattering experiment. The nuclear spin of helium-3 is used as an internal clock for the beam particles resulting in a phenomenally high energy resolution, and a unique ability to study atomic-scale surface motion on a pico to nano-second timescale [1]. A second recent research activity involves using the source of the helium-3 spin echo apparatus to magnetically focus and spin separate a beam of water molecules [2]. In this experiment ortho and para water molecules are separated by passing the beam through a strong magnetic field gradient. The high purity beam which is obtained in this experiment offers a method for studying the properties of the two spin isomers and their interaction with surfaces. In addition, since our apparatus selects a well defined spin state it has the potential to dramatically increase the sensitivity of an NMR experiment (~5 orders of magnitude), a property which could make sub-monolayer proton NMR studies possible in the near future.