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, C₂ F₆, 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