Guiding of highly charged ions by highly orderedSiO2nanocapillaries

Abstract

We report a narrow angular distribution of 0.8\ifmmode^\circ\else\textdegree\fi{}, close to that expected from the aspect ratio, for guiding of highly charged ions through a well-ordered, parallel $\mathrm{Si}{\mathrm{O}}_{2}$ nanocapillaries target. These capillaries were obtained by thermally oxidizing a $25\text{\ensuremath{-}}\ensuremath{\mu}\mathrm{m}$-thick membrane of silicon nanocapillaries fabricated by photoassisted electrochemical etching. The diameter of the uniformly distributed capillaries was $100\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. We observed ${\mathrm{Ne}}^{7+}$ ions being transmitted through these nanocapillaries with a decreasing transmitted intensity up to a factor 100, when increasing the capillary tilt angles up to 4\ifmmode^\circ\else\textdegree\fi{}. The narrower angular distribution in comparison to polyethylene terephthalate capillaries is discussed and it is shown that the $\mathrm{Si}{\mathrm{O}}_{2}$ results support the model of self-organized charge patches formed at the capillary entrance.