Experimental and theoritical research on the dynamical transmission of 30 keV H+ ions through polycarbonate nanocapillaries

Abstract

The ions with different incident energies transmitting through insulating nanocapillaries are studied in various configurations. For the low energy ions transmitting through nanocapillaries, Stolterfoht et al.[2002 Phys. Rev. Lett. 88 133201] have observed the guiding effect. Subsequent studies revealed that the self-organizing charge patches on the capillary wall inhibit charge exchange and the ions are transmitted along the capillary axis direction. The high energies of ions transmitting through nanocapillaries are measured, the main transmission mechanism is multiple random inelastic collisions below the surface, and the charge patches will not affect the transmitted ions trajectories. The transmission features of the intermediate energy ions are different from those of the low and high energy ions. The ion beams with intermediate energies have many applications, so it is necessary to understand the transmission features of the intermediate energy ions though nanocapillaries. Recent studies have focused on the transmission of the intermediate energies ions through the nanocapillaries. In the present work, we investigate thie transmission features, such as the two-dimensional transmitted angular distributions, the charge states and position distributions, and the evolution of the relative transmission rate and the charge purity of 30 keV H+ transmitting through nanocapillaries in a polycarbonate membrane at the angles of-1 and-2. The experimental data clearly show that the transmitted H+ ions consist of the transmitted scattering H+ ions, which are located around the direction of the incident beam, and the transmitted guiding H+ ions, which are located around the direction of the capillary axis. With the charges depositing in the capillary, the proportion of the transmitted scattering H+ ions increases and the proportion of the transmitted guiding H+ ion decreases, which directly demonstrates the dynamical evolution of the scattering ions and the guiding ions. To understand the competition between the transmitted scattering ions and the transmitted guiding ions and the physical picture of the intermediate energy ions transmitting through the insulating nanocapillaries, the trajectories of the H+ ions in the capillary and the potential distribution and electric field intensity distribution in the capillary are numerically simulated. The results show that the potential distributions and electric field intensitiesy are different for H+ ions transmitting through nanocapillaries at various tilt angles, and the simulation results are in good agreement with the experimental data. The experimental and simulation results give us a further insight into the mechanisms of guiding and scattering in intermediate energy ions transmitting through nanocapillaries.