Investigation of Al-blow-off beam composition using a time-of-flight mass-spectrometer

A ToF mass spectrometer was used to find out from an Al blow-off beam the constituent atoms, molecules or clusters. An Al layer from a glass disc was shot by a rubby laser, and the neutral part of the beam flew through a diaphragm into the M.S. The neutral particles were ionized by the pulse of an examiner laser focused to the target-point, one mm after the diaphragm. The neutral particles supposedly consisted of different numbers of atoms, should have different velocities and could be separately investigated by changing the delay time between the two laser-shots. The measurements showed, that there were only single Al atoms and double Al2 molecules (dimers) in the Al-beam. (author) 2 refs.; 9 figs