Al2O3 Nanocapillaries Research Articles

Interaction of 30 keV O3+ ions with Al2O3 nanocapillaries

Interaction of 30keV O3+ ions with capillaries in an Al2O3 membrane was studied. The charge state distribution and the angular distribution of the ions transmitted through the capillaries were measured. Shifts of the transmission profile centroid by twice of the capillary tilt angle ψ and double-peak structure in the transmission profile were found. Difficulties exist in determination of the impact point location on the capillary wall and the scattering angle for each collision to interpret the observed 2ψ shift phenomenon. The transmission profile width and ion guiding ability of the concerned capillaries for the used projectile ions were analyzed. Comparison of the present guiding angle and the prediction of scaling laws was conducted. Further work concerning the influence of the material and its surface treatment on the guiding properties is needed.

Transmission of electrons through Al2O3 nanocapillaries

We investigate transmission of low-energy electrons (250 eV) through insulating Al2O3 nanocapillaries (270 nm diameter and 15 μm length). Kinetic energy distribution of electrons transmitted through the nanocapillaries in the straightforward direction, time dependence of the transmission rate both in the straightforward direction and for tilted capillaries and angular distributions of electrons transmitted at the incident energy are presented and discussed.

Transmission of 16 keV Cu− ions through Al2O3 nano-capillaries

The interaction of 16keV Cu− ions with Al2O3 nano-capillaries of 50nm diameter and 10μm length was studied. The angular and charge state distributions of the transmitted particles were measured by a position-sensitive microchannel plate detector. It shows that transmitted particles appear as two peaks and consist of three charge states, Cu−, Cu0 and Cu+. As the tilt angle increases, more Cu− ions lose electrons resulting in the formation of Cu0 and Cu+ during multiple collisions with the capillary walls. Unlike previously reported results on highly charged ions, keV-energy Cu− ions undergo significant charge exchange processes with the inner walls of the capillaries. This indicates that the guiding effect is absent in the negative ion transmission under the very low ion current conditions.

Charging dynamics in electron transmission through Al2O3 capillaries

We have measured the transmission of low-energy (E=250eV) electrons through insulating Al2O3 nanocapillaries. We find that transmission at the incident energy is quickly suppressed with increasing tilt angle ψ of the capillary axis relative to the incoming electron beam while inelastic transmission becomes more important. For small angles of incidence charging dynamics lead to a decrease of total transmission (elastic and inelastic) with time. Our results are interpreted on the basis of a microscopic model for the electron transport within the capillary including also close interactions with the capillary wall.

Charge exchange of keV O− ions transmitted through Al2O3 nano-capillaries

The transmission of 10–18 keV O− ions through Al2O3 nano-capillaries has been investigated experimentally. From the angular distribution of the transmitted particles, O0 and O− and O+ ions can be distinguished in the mixed scattered beams. The fractions of the scattered ions increase with both the tilt angle and the incident energy, which indicates strongly that there is dynamical charge exchange in the scattering of negative ions on the insulator surface. Moreover, it is found that the scattered neutrals (O0) are only more or less guided along the capillary axis, which is greatly different from the case of the guiding effect of highly charged ions.

Transmission of 18 keV negative ions Cl− through nanocapillariesin Al2O3 membrane

We investigate the angular distribution of the transmitted 18 keV negative ions Cl− through Al2O3 nanocapillaries of 50 nm in diameter and 10 μm in length. Elastic scattering ions and inelastic scattering ions are obtained simultaneously. The experimental result is partially consistent with the guiding effect. We can qualitatively explain our experimental result through a dynamic process.

Guiding of 60 keV O+ ions through Al2O3 nanocapillaries with two different diameters

The transmission of 60 keV O+ ions through Al2O3 nanocapillaries at a series of different tilt angles is measured. The capillaries with diameters of 50 nm and 30 nm respectively and 10 μm in length are used. The angular distribution and the transmission yields of transported ions are investigated. Our results indicate both the existence of guiding effect when ions pass through the capillary and a significant dependence on the tilt angle. The results also show that the transmission yield increases as the diameter of capillary decreases，and the theoretical model used in our work explains it well.

Guided transmission of oxygen ions through Al2O3 nanocapillaries

The transmissions of oxygen ions through Al2O3 nanocapillaries each 50 nm in diameter and 10 μm in length at a series of different tilt angles are measured, where the ions with energies ranging from 10 to 60 keV and charge states from 1 up to 6 are involved. The angular distribution and the transmission yields of transported ions are investigated. Our results indicate both the existence of a guiding effect when ions pass through the capillary and a significant dependence of the ion transmission on the energy and the charge state of the ions. The guiding effects are observed to be enhanced at lower projectile energies and higher charge states. Meanwhile, the results also exhibit that the transmission yields increase as the tilt angle decreases at a given energy and charge state.

Interaction of O3+ Ions with Al2O3 Nanocapillaries

We investigate angular distributions of the transmitted 60 keV and 120 keV O3+ ions through nanocapillaries with 50nm diameter and 10μm length. The experimental results are in agreement with the ‘guiding effect’ found by Stolterfoht et al. For different tilted angles of the nanocapillary membrane with respect to the beam, the angular distributions of the transmitted ions are measured by a one-dimensional micro-channel plate (MCP) detector. Moreover, the dependence of this guiding effect on the projectile energy is studied.

Guiding of highly charged ions through Al2O3 nano-capillaries

Over the past years, our group has performed experiments on ion guiding in nano-capillary membranes of polyethylene terephthalate (PET), SiO2 and Al2O3. In this paper we report the results from our recent experiments on guiding of 7keV Ne7+-ions in Al2O3 nano-capillaries of about 1/200 aspect ratio. We will compare these experimental findings with previously obtained and published results of different membrane materials.