Seminar org anised by EMAT

Subject : Big-Bang tomography : a new route to atomic resolution tomography

Speaker: D. Van Dyck, EMAT, University of Antwerp

Abstract:

Classical tomographic schemes make use of a large series of projections of an object taken at small angular increments. However for atomic resolution tomography this can pose many problems. First it is not straightforward to perform mechanical tilting in an EM with sub-Angstrom precision over a very large angular range. Secondly many real-life objects such as e.g. an amorphous dielectric layer in a microelectronic device have a geometry that does not give this degree of freedom. And thirdly many objects such as proteins are sensitive to radiation damage so that they do not allow sufficient experimental time and dose for a full tomographic reconstruction at high resolution.

Hence there is need for a new tomographic scheme that can is able to deduce 3D information from only one projection, or from 2 projections using stereoscopy.

In this lecture I will present a totally new tomographic scheme that in principle allows to determine not only the position of individual atoms within the plane of observation but also the vertical position with sub Angstrom precision. For reasons of analogy and intuitive understanding we have called it “big-bang tomography”. We have applied it successfully to the study of a two-layer graphene object.

When and where: Friday, March 23, 2012 at 11.30 h in room X.009, Campus Groenenborger