Interaction of highly charged ions (HCI) with solids

Since the beginning of my scientific work, I have been involved in the experimental and theoretical investigation of the interaction of mostly slow, highly charged ions with solid surfaces. Starting with the description of electron emission statistics based on the classical over-the-barrier model [1], through the coincidence measurement of scattered projectiles with the number of emitted electrons [2], to the modeling of surface modifications due to local melting of the crystal by ion impact, numerous projects have been implemented [3,4].
We are currently investigating the deposition of the potential energy of highly charged ions around the impact point and the resulting changes in the structure of 2- and 3-dimensional crystals. Experimental results from the Wilhelm group at IAP were simulated in close collaboration with the experimentalists, and further projects in this area are currently underway (project work possible at any time).

[1] J. Burgdörfer, P. Lerner, F.W. Meyer, Phys. Rev. A 44, 5674 (1991), opens an external URL in a new window.

[2] C. Lemell, J. Stöckl, J. Burgdörfer, G. Betz, HP. Winter, and F. Aumayr, Phys. Rev. Lett. 81, 1965 (1998), opens an external URL in a new window.

[3] A. S. El-Said, R. A. Wilhelm, R. Heller, S. Facsko, C. Lemell, G. Wachter, J. Burgdörfer, R. Ritter, F. Aumayr, Phys. Rev. Lett. 109, 117602 (2012), opens an external URL in a new window.

[4] A. Sagar Grossek, A. Niggas, R.A. Wilhelm, F. Aumayr, C. Lemell, Nano Lett. 22, 9679 (2022), opens an external URL in a new window.

Ions with different poten tial energy hit a surface

Scenario for surface modification as a function of charge q or, equivalently, the potential energy of highly charged ions. Depending on the charge state, non-etchable single defects (low charge; left column), etchable defect clusters (middle column), and clearly visible elevations (high charge; right column) are formed. Image from [3]

Interaction of strong, ultrashort laser pulses with matter

The interaction of strong fields with matter leads to nonlinear effects that trigger a series of interesting processes. Our work ranges from studying the photoelectron spectrum of atoms, diatomic molecules, very sharp metal needles, or metal surfaces [1-3] to the emission of high-frequency radiation (“high harmonics generation”) from atoms, molecules, and solids [4,5]. We also investigate charge transport in insulators under the influence of strong laser fields [6]. To simulate these processes, we use semiclassical methods, solve the time-dependent Schrödinger equation, or reproduce the systems in large program packages for time-dependent density functional calculations. All research in this area is conducted in close collaboration with experimental groups.

[1] A. Suñer-Rubio, C. Lemell, R.Y. Bello, J. Burgdörfer, A. Palacios, F. Martín, Phys. Rev. Res. 6, L022066 (2024), opens an external URL in a new window.

[2] M. Krüger, C. Lemell, G. Wachter, J. Burgdörfer, P. Hommelhoff, J. Phys B 51, 172001 (2018), opens an external URL in a new window.

[3] D. Potamianos, M. Schnitzenbaumer, C. Lemell, P. Scigalla, F. Libisch, E. Schock-Schmidtke, M. Haimerl, C. Schröder, M. Schäffer, J.T. Küchle, J. Riemensberger, K. Eberle, Y. Cui, U. Kleineberg, J. Burgdörfer, J.V. Barth, P. Feulner, F. Allegretti, R. Kienberger, Science Adv. 10, eado0073 (2024), opens an external URL in a new window.

[4] M. Monfared, E. Irani, C. Lemell, J. Burgdörfer, Phys. Rev. A 106, 053108 (2022), opens an external URL in a new window.

[5] I. Floss, C. Lemell, K. Yabana, J. Burgdörfer, J. Phys.: Conf. Ser. 1412, 082007 (2020), opens an external URL in a new window.

[6] M. Ossiander, K. Golyari, K. Scharl, L. Lehnert, F. Siegrist, J.P. Bürger, D. Zimin, J.A. Gessner, M. Weidman, I. Floss, V. Smejkal, S. Donsa, C. Lemell, F. Libisch, N. Karpowicz, J. Burgdörfer, F. Krausz, M. Schultze, Nature Comm. 13, 1620 (2022), opens an external URL in a new window.

Evolution of a high harmonics spectrum along the propagation direction within a diamond crystal

Spectrum (log scale) of high harmonics induced in diamond by an intense, ultrashort laser pulse. Propagation in the medium causes the spectrum to change as a function of position in the 1 µm thick crystal (image from [5]).

Teaching

  • Angewandte Quantenmechanik (132.070)
  • (Introduction to) Quantum Physics: Basic Concepts and Foundations (194.171, 194.169)
  • Wissenschaftliches Programmieren (138.089)
  • Numerische Methoden und Simulation (138.094)
  • Statistische Physik II (132.065, 136.050)

Publications

Publications in TU-Datenbase, opens an external URL in a new window