The influence of fine-structure splitting on the mobility of atomic neon ions in neon

The mobilities of atomic neon ions in the 2 P 1/2 and 2 P 3/2 states have been measured in neon at 77, 78 and 294K and compared to the theoretical predictions of Cohen and Schneider (1975). The absolute values of the mobilities have been found to disagree with those calculated by as much as 10% which is well outside the experimental uncertainty. Theory and experiment agree that (i) at low average centre-of-mass energies the mobility of Ne + ( 2 P 1/2 ) in Ne is smaller than that of Ne + ( 2 P 3/2 ) in Ne, (ii) the difference in the mobilities decreases as the ion energy increases and (iii) both ion species show a negative temperature dependence of their mobility.