Mobilities and collision cross sections of Cl− ⋅ nH2O ions in argon, krypton, and xenon

Clustered chloride ions of the formula Cl− ⋅ nH2O, with n predominantly 3 or 4, have been made in argon, krypton, and xenon, and their mobilities measured by a drift technique as a function of inert gas pressure over the range 25 to 1000 Torr. Mobilities at 296 K and inert gas densities of 2.69×1019 molecule cm−3 were: 2.03, 1.26, and 0.81 cm2 V−1 s−1 in argon, krypton, and xenon, respectively. Comparison with theory shows that a significant inverse sixth power attractive potential is required to explain the magnitudes of the collision cross sections.