On the excitation mechanism of the CW atomic fluorine laser

A plasma mixing device in which a helium plasma beam is crossed with a molecular fluorine beam was used to operate an atomic fluorine laser. Operation conditions confirm that excitation occurs through collisions of helium metastables and F2 molecules. Collisions with other F-donors such as NF3, CF4, C2F6, and SF6 do not yield F-atoms in one of the possible upper laser levels. In lasers using such F-donors, excitation has to occur through electron collisions with F-atoms which have been generated in a preceding process