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Title: Guiding of highly charged ions by highly ordered SiO{sub 2} nanocapillaries

Abstract

We report a narrow angular distribution of 0.8 deg., close to that expected from the aspect ratio, for guiding of highly charged ions through a well-ordered, parallel SiO{sub 2} nanocapillaries target. These capillaries were obtained by thermally oxidizing a 25-{mu}m-thick membrane of silicon nanocapillaries fabricated by photoassisted electrochemical etching. The diameter of the uniformly distributed capillaries was 100 nm. We observed Ne{sup 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 deg. The narrower angular distribution in comparison to polyethylene terephthalate capillaries is discussed and it is shown that the SiO{sub 2} results support the model of self-organized charge patches formed at the capillary entrance.

Authors:
; ; ; ;  [1]
  1. Atomic Physics, Fysikum, AlbaNova, S-10691 Stockholm (Sweden)
Publication Date:
OSTI Identifier:
20787040
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 73; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevA.73.040901; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 36 MATERIALS SCIENCE; ANGULAR DISTRIBUTION; ASPECT RATIO; CAPILLARIES; CATIONS; COMPARATIVE EVALUATIONS; ELECTROCHEMISTRY; ETCHING; MEMBRANES; MULTICHARGED IONS; NEON; OXIDATION; POLYESTERS; SILICA; SILICON; SILICON OXIDES; SURFACES

Citation Formats

Sahana, M. B., Skog, P., Vikor, Gy., Kumar, R. T. Rajendra, and Schuch, R. Guiding of highly charged ions by highly ordered SiO{sub 2} nanocapillaries. United States: N. p., 2006. Web. doi:10.1103/PHYSREVA.73.0.
Sahana, M. B., Skog, P., Vikor, Gy., Kumar, R. T. Rajendra, & Schuch, R. Guiding of highly charged ions by highly ordered SiO{sub 2} nanocapillaries. United States. doi:10.1103/PHYSREVA.73.0.
Sahana, M. B., Skog, P., Vikor, Gy., Kumar, R. T. Rajendra, and Schuch, R. Sat . "Guiding of highly charged ions by highly ordered SiO{sub 2} nanocapillaries". United States. doi:10.1103/PHYSREVA.73.0.
@article{osti_20787040,
title = {Guiding of highly charged ions by highly ordered SiO{sub 2} nanocapillaries},
author = {Sahana, M. B. and Skog, P. and Vikor, Gy. and Kumar, R. T. Rajendra and Schuch, R.},
abstractNote = {We report a narrow angular distribution of 0.8 deg., close to that expected from the aspect ratio, for guiding of highly charged ions through a well-ordered, parallel SiO{sub 2} nanocapillaries target. These capillaries were obtained by thermally oxidizing a 25-{mu}m-thick membrane of silicon nanocapillaries fabricated by photoassisted electrochemical etching. The diameter of the uniformly distributed capillaries was 100 nm. We observed Ne{sup 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 deg. The narrower angular distribution in comparison to polyethylene terephthalate capillaries is discussed and it is shown that the SiO{sub 2} results support the model of self-organized charge patches formed at the capillary entrance.},
doi = {10.1103/PHYSREVA.73.0},
journal = {Physical Review. A},
number = 4,
volume = 73,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • The time evolution of angular distributions of 7-keV Ne{sup 7+} ions transmitted through SiO{sub 2} nanocapillaries is studied starting with already-charged capillaries, as well as with fully discharged capillaries, under well-defined conditions. We deduce the rearrangement of charge patches for the charged capillaries from the time evolution of the angular distributions. The rearrangement time is found to be orders of magnitude shorter than the discharge time. Combined with a model calculation, we derive quantitative information on the formation of charge patches downstream of the entrance patch during charging-up, starting with the fully discharged capillaries. A pattern of a small numbermore » of charge patches guiding ions is deduced in the stationary state of transmission. The model predicts the width and broadening of the transmitted intensity in accord with measurements. We find strong evidence that the deposited charge patches, formed during charge-up, remain localized in the steady state of ion transmission.« less
  • We report an experimental study of guided transmission of low-energy (200-350 eV) electrons through highly ordered Al{sub 2}O{sub 3} nanocapillaries with large aspect ratio (140 nm diameter and 15 {mu}m length). The nanochannel array was prepared using self-ordering phenomena during a two-step anodization process of a high-purity aluminum foil. The experimental results clearly show the existence of the guiding effect, as found for highly charged ions. The guiding of the electron beam was observed for tilt angles up to 12 degree sign . As seen for highly charged ions, the guiding efficiency increases with decreasing electron incident energy. The transmissionmore » efficiency appeared to be significantly lower than observed for highly charged ions and, moreover, the intensity of transmitted electrons significantly decreases with decreasing impact energy.« less
  • In this work, the efficient electron loss process was observed for the transmission of 10- to 18-keV Cu{sup -} and Cl{sup -} ions through Al{sub 2}O{sub 3} nanocapillaries. The fractions of the scattered particles were simultaneously measured using a position-sensitive microchannel plate detector. The neutrals were guided through the capillary via multiple grazing scattering. In particular, the scattered Cl{sup -} ions were observed in the transmission, whereas no Cu{sup -} ion was formed. In contrast to highly charged ions, these results support strongly the fact that the scattering events dominate the transport of negative ions through the nanocapillaries and thatmore » there is no direct evidence for the formation of negative charge patches inside the capillaries which are able to repulse and guide negative ions efficiently.« less
  • The transmission of 18-keV O{sup -} ions through Al{sub 2}O{sub 3} nanocapillaries with 50 nm in diameter and 12 {mu}m in length is studied in this work. By measuring angular distribution of transmitted particles when capillaries were tilted with respect to incident ion beam, two peaks were observed. It is distinguished that one of them is composed by direct transmitted ions and another one is composed by scattered ions. A phenomenon referred to as guiding effect, as found for highly charged ions and low-energy electrons, was observed. When negative ions (18-keV O{sup -}) are transmitted through nanocapillaries, most of themmore » were ionized to neutral atoms and even positive ions. The intensity of transmitted particles (O{sup -}, O{sup 0}, and O{sup +}) decreased when the tilt angle increased. In transmitted particles, the fraction of O{sup -} declined but that of O{sup 0} and O{sup +} ions grew when the tilt angle grew. Both elastic collision and electrostatic scattering were found in scattered ions.« less
  • The transmission of highly charged ions through nanocapillaries in insulating polyethylene terephthalate (PET) polymers was investigated. In experiments at laboratories in RIKEN (Japan) and HMI (Germany) 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 themore » 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 (exponential) expression for the discharge current.« less