50 years of ion channeling in materials science - where do we go next?

Inst. Kern- en Stralingsfysica, KU Leuven, B-3001 Leuven, Belgium

When nuclear physicists started abandoning their small accelerators in the sixties, research activities in ion beam – solid interactions were booming. Among others, it was discovered that energetic charged particles can be steered through a single crystal over a long distance, without undergoing any large-angle scattering. This effect, well-known as (ion) channeling, was computationally predicted by Robinson and Oen, experimentally confirmed by 3 groups independently and to a large extent theoretically explained by Lindhard – in merely a couple of years (1962-1965)!

Since then, numerous variations of the channeling effect have been used and even proven crucial in a wide scala of materials science investigations. Any material property which is related to (a deviation of) its crystallinity can be investigated with the same depth, elemental, isotopic… resolution as the ion beam analysis technique it is based on, e.g. Rutherford backscattering spectrometry, particle-induced X-ray emission, nuclear reaction analysis…  In this talk, we will dwell on a number of the paramount advances, which brought along the strength of the ion channeling technique, even beyond its standard use.

These include examples where ion beam analysis has been driven to its extremes, where the experiment was performed in exotic conditions, or where non-conventional schemes or approaches were used – including progress in the experimental set-up and in simulations of the channeling effect. Moreover, we will reflect on the future of ion channeling during the decades to come. In particular: what will the role of channeling be in a research era which largely focuses on structures and properties at the nanometer-scale? It is anticipated that channeling will remain competitive with and complementary to other characterization techniques providing (local) structural information, including synchrotron-based approaches and state-of-the-art electron microscopy.