Guiding of slowNe7+ions through nanocapillaries in insulating polyethylene terephthalate: Incident current dependence

Abstract

The transmission of highly charged ions through nanocapillaries in insulating polyethylene terephthalate ͑PET͒ polymers was investigated. In experiments at laboratories in RIKEN ͑Japan͒ and HMI ͑Germany͒ different detection methods were applied to study the ion current dependence in a wide range covering two orders of magnitude. At HMI an electrostatic ion spectrometer was used and at RIKEN a two-dimensional position sensitive detector was implemented. New PET samples with parallel capillaries and low density were manufactured. For tilted capillaries, the ions are guided along the capillary axis, since the majority of ions are deflected in a charge patch created in the capillary entrance. The results provide insights into the mechanisms of capillary guiding. The fraction of transmitted ions was found to be nearly independent on the incident ion current indicating a sudden increase in the discharge current depleting the entrance charge patch. The experimental results were well-reproduced by model calculations based on a nonlinear ͑exponential͒ expression for the discharge current.

Density effects on the guided transmission of 3keV Ne7+ ions through PET nanocapillaries

“…5 shows that for the capillary density of 4 Â 10 6 cm À2 the profile width r t increases by a factor of 2 as the tilt angle increases from 0 to 8 . Results obtained in previous measurements at HMI Berlin [18] (see the solid square), show good agreement with the present results. However, previous measurements at RIKEN [10] with the same low-density capillaries yielded controversial results.…”

“…Moreover, measurements performed shall guide the eye. In (b) previous results indicated by a triangle [10,18] and a square [18] are also shown. The data for the transmitted ion fraction (lower row) are normalized to unity for w ¼ 0.…”

“…For a tilted foil the deposited charge in the entrance region increases until the electrostatic field is sufficiently high for a deflection of the ions towards the direction of the capillary exit. The capability of insulating capillaries to guide ions is referred to as the guiding power [18,19]. The fraction of transmitted ions at equilibrium generally decreases with tilt angle w. The guiding power can be quantized by the guiding angle w c for which the normalized transmission fraction drops to 1=e.…”

Ion guiding in alumina capillaries: MCP images of the transmitted ions

“…Insulating nanocapillaries have attracted considerable attention since the discovery of capillary guiding [1][2][3][4][5][6][7][8]. Ions with a few keV kinetic energy are efficiently transmitted through the capillaries of thin insulating foils mostly in their initial charge state, and the transmitted ions are directed along the capillaries with a narrow angular distribution.…”

“…They might be used for irradiating single cells and writing on charge sensitive surfaces. Collecting experimental data with capillary samples made of different kinds of materials is of a great importance for the understanding of this self-organizing phenomenon [1][2][3][4][5][6][7][8][9].…”