Angular Distributions of Ions Transmitted by a Nanocapillary Array

Angular distributions of incident 10--20 keV/q multi-charged ions of Ar and Ne (q=3,7) transmitted in an aluminum oxide nanocapillary array were studied. The diameter and length of the pores are 100 nm and 60 micron, respectively. Charge-state selected angular distributions were obtained. The principal transmitted q-state (incident q-state) is about seven orders of magnitude smaller than the surface porosity ($\sim $30{\%}). The angular distributions, composed of many narrow peaks, can be steered in the longitudinal direction of the nanopores within $\sim \quad \pm $ 1 degrees by rotating the sample with respect to the incident beam. Target tilting experiments prove that the angular structure arises when ions bounce at ultra-low grazing angles in very large impact parameter ($>$10 nm) Coulomb collisions with electrically charged nanopore walls.$\backslash $This work was supported by the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy under Contract No.DE-AC05-00OR22725 with UT-Battelle, LLC.