Processes in the ionization volume of the nano-aperture ion source

The primary purposes of the nano-aperture ion source is emitting ions. However, in the ionization region various other processes occur which may lead to the emission of other species. A theoretical study on such processes was conducted for argon. Besides single charged ions, multiple charged ions become constituents of the beam when using electron impact energies above the second ionization threshold. Rather surprisingly, a small amount of diatomic charged argon is predicted to become part of the beam. For a 1 keV electron beam we expect the beam to consist of about 88% single charged argon, 8% double charged argon, 2% triple charged argon, and 2% diatomic single charged argon.