Negative ion production rates in rare gas-halide lasers

This paper reports on dissociative electron attachment in F
2
, NF
3
, Cl
2
, and I
2
. The principle of the method is to produce a short burst of photoelectrons from a photocathode by means of light from an argon-fluoride laser. Subsequently, by studying the motion of electrons and negative ions in a constant electric field (
E
) region, information is obtained about drift velocities and effective attachment cross sections. Helium, argon, and nitrogen were used as buffer gases. Of particular interest is a very strong temperature dependence of the attachment coefficient in I
2
. Measurements were taken from 35 to 110°C, covering an
E/N
range of 1-50 Townsend. An explanation based on vibrational excitation is presented.