The effect of internal energy on the lifetime of sulfur hexafluoride negative ions
Dunning, F. B.
Master of Science
The lifetimes of SF-6 ions produced in K(np)/SF6 collisions at high n are being investigated as a function of target temperature over the range 300K to 600K. At room temperature collisions are found to lead predominantly to the formation of long-lived SF-6 ions with lifetimes tau ≳ 1ms. As the target temperature is raised long-lived (tau ≳ 0.5ms) ions are still observed but their mean lifetime is reduced. In addition, the growth of a short-lived ion signal (tau ≳ 10 mus) is evident which, by 600K, accounts for ∼45% of the total SF-6 ion signal. These lifetimes are compared with those obtained using quasi-equilibrium theory and calculated SF-6 vibrational frequencies.
Physical chemistry; Molecular physics; Atomic physics