Alkali atoms in a very wide velocity range are produced by a sputtering source. The sputtering is produced by bombardment of an alkali target (2) with an Ar+ beam from a unoplasmatron (1) ion source . Under working conditions a current of 1.5mA at 13keV is focussed in a rectangle of 1 x 10mm2. The spot is out of the centre of the target which is rotated to get uniform sputtering. The energy of the atoms obtained in this way ranges from thermal up to several tens of eV.
We probably have observed collisional ionization between these dimers and the target molecules as was shown by .