Highly charged ions
Highly charged ions (HCI) carry besides their kinetic energy a large amount of potential energy, which is defined as the sum of the binding energies of all missing electrons. For slow HCI the potential energy may exceed the kinetic energy by far. Upon impact of a HCI on a solid surface the ion attracts electrons from the surface, which leads to its neutralization and the deposition of the potential energy in the surface (Fig. 1).
During this short period of time (typically a few femtoseconds (10-15s)) and the small impact area of a few nm2 power densities of up to 1014W/cm2 are reached. The formation of a large variety of surface nano-structures is expected due to these high power densities. In comparison to conventional types of ions, i.e. single charge ions or swift heavy ions (SHI) highly charged ions deposit their potential energy only in a shallow surface layer (Fig. 2).
Our research focuses on
- Charge exchange and energy loss of highly charged ions in nanomembranes and 2d materials
- Identification and control of surface nano-structures due to potential energy deposition
Fig. 1: Schematic view of the interaction of a highly charged ion with a surface: "Classical Over the Barrier Model" (from HP. Winter, F. Aumayr and J. Burgdörfer).
|Fig. 2: The energy deposition of HCI is confined to a shallow surface region, in contrast to other types of ions.|
- R. A. Wilhelm, E. Gruber, J. Schwestka, R. Kozubek, T. I. Madeira, J. P. Marques, J. Kobus, A. V. Krasheninnikov, M. Schleberger, and F. Aumayr, Interatomic Coulombic Decay: The Mechanism for Rapid Deexcitation of Hollow Atoms, Phys. Rev. Lett. 119, 103401 (2017) [doi: 10.1103/PhysRevLett.119.103401].
- E. Gruber, R.A. Wilhelm, R. Pétuya, V. Smejkal, R. Kozubek, A. Hierzenberger, B.C. Bayer, I. Aldazabal, A.K. Kazansky, F. Libisch, A.V. Krasheninnikov, M. Schleberger, S. Facsko, A.G. Borisov, A. Arnau, and F. Aumayr, Ultrafast electronic response of graphene to a strong and localized electric field, Nat Comms 7, 13948 (2016) [doi: 10.1038/ncomms13948].
- A.S. El-Said, R.A. Wilhelm, R. Heller, M. Sorokin, S. Facsko, and F. Aumayr, Tuning the Fabrication of Nanostructures by Low-Energy Highly Charged Ions, Phys. Rev. Lett. 117, 126101 (2016) [doi:10.1103/PhysRevLett.117.126101].
- R.A. Wilhelm, E. Gruber, V. Smejkal, S. Facsko, and F. Aumayr, Charge-state-dependent energy loss of slow ions. I. Experimental results on the transmission of highly charged ions, Phys. Rev. A 93, 052708 (2016) [doi:10.1103/PhysRevA.93.052708].
- R.A. Wilhelm and W. Möller, Charge-state-dependent energy loss of slow ions. II. Statistical atom model, Phys. Rev. A 93, 052709 (2016) [10.1103/PhysRevA.93.052709].
- R.A. Wilhelm, E. Gruber, R. Ritter, R. Heller, A. Beyer, A. Turchanin, N. Klingner, R. Hübner, M. Stöger-Pollach, H. Vieker, G. Hlawacek, A. Gölzhäuser, S. Facsko, and F. Aumayr, Threshold and efficiency for perforation of 1 nm thick carbon nanomembranes with slow highly charged ions, 2D Mater. 2, 1 (2015) [10.1088/2053-1583/2/3/035009].
- R.A. Wilhelm, A.S. El-Said, F. Krok, R. Heller, E. Gruber, F. Aumayr, and S. Facsko, Highly charged ion induced nanostructures at surfaces by strong electronic excitations, Prog. Surf. Sci. 90, 377 (2015) [doi:10.1016/j.progsurf.2015.06.001].
- R.A. Wilhelm, E. Gruber, R. Ritter, R. Heller, A. Beyer, A. Turchanin, N. Klingner, R. Hübner, M. Stöger-Pollach, H. Vieker, G. Hlawacek, A. Gölzhäuser, S. Facsko, and F. Aumayr, Threshold and efficiency for perforation of 1 nm thick carbon nanomembranes with slow highly charged ions, 2D Mater. 2, 1 (2015) [doi:10.1088/2053-1583/2/3/035009].
- R.A. Wilhelm, E. Gruber, R. Ritter, R. Heller, S. Facsko, and F. Aumayr, Charge Exchange and Energy Loss of Slow Highly Charged Ions in 1 nm Thick Carbon Nanomembranes, Phys. Rev. Lett. 112, 153201 (2014) [doi:10.1103/PhysRevLett.112.153201].
- A.S. El-Said, R. Heller, R.A. Wilhelm, S. Facsko, and F. Aumayr, Surface modifications of BaF2 and CaF2 single crystals by slow highly charged ions, Appl. Surf. Sci. 310, 169 (2014) [doi:10.1016/j.apsusc.2014.03.083].
- Ritter, R., Wilhelm, R.A., Stöger-Pollach, M., Heller, R., Mücklich, A., Werner, U., Vieker, H., Beyer, A., Facsko, S., Gölzhäuser, A., Aumayr, F., Fabrication of nanopores in 1nm thick carbon nanomembranes with slow highly charged ions, Appl. Phys. Lett. 102, 063112, 2013 [doi:10.1063/1.4792511].