(424c) Dynamics of Ion Transport in Single-Walled Carbon Nanotubes As a Function of Diameter and Temperature

The study of transport through nanopores is a growing field of research due to the possibility of inexpensive DNA sequencing, single-molecule detection, and incorporation into efficient membranes. Our previous studies^1,2 demonstrated the presence of the Coulter effect when individual ions block an otherwise stable proton current flowing through the interior of the carbon nanotube. In this study, we demonstrated further evidence for this mechanism by showing the inverse relationship between dwell times and applied voltage, which indicate the presence of a charged blocker. Furthermore, temperature experiments demonstrate the possibility of an activated process involved in the ion translocation. Finally, Raman spectroscopy was used to characterize the diameter of individual single-walled carbon nanotubes before they were incorporated into devices. Stochastic ion pore-blocking was observed for several devices containing SWNT of diameters ranging from 0.9 and 2.0 nm. Interestingly, we observe a maximum blocked proton current around a nanotube diameter of 1.6 nm, with decreased pore-blocking currents at smaller and larger diameters.

1. Lee, C. Y., Choi, W., Han, J.-H., & Strano, M. S. (2010). Coherence Resonance in a Single-Walled Carbon Nanotube Ion Channel. Science, 329(5997), 1320-1324.
2. Choi, W., Lee, C. Y., Ham, M.-H., Shimizu, S., & Strano, M. S. (2010). Dynamics of Simultaneous, Single Ion Transport through Two Single-Walled Carbon Nanotubes: Observation of a Three-State System. Journal of the American Chemical Society, 133(2), 203-205.