Next November 20, the UltraSTEM scanning transmission electron microscope, a unique instrument in France, will be inaugurated at the Laboratory of Solid State Physics (LPS), Paris-Sud Orsay University. During the event, the national platform called METSA (French acronym for Transmission Electron Microscope and Atomic Probe) will also be inaugurated. METSA, also one-of-a-kind in France, will be bringing together six major French electron microscope centers. The facility will be open to research teams and to collaborative endeavors with industry operators. METSA (http://www.metsa.cnrs.fr) Webmaster Jérôme Majimel, a research fellow in the 'Functionalized Materials' team, Bordeaux Institute of Chemistry and Condensed Matter (ICMCB/CNRS), explains why scanning transmission electron microscopes are critical tools and talks about his research with his team.
Interview by Jean-François Desessard.
BE France - Are we seeing a skyrocketing growth of transmission electron microscopy?
Jérôme Majimel - Absolutely. Actually, this is why the CNRS backed the setup of the METSA platform. It is a national Microscopy and Atomic Probe network involving six major French centers. Any research team who so desires as well as industry operators, through collaborative endeavors with different laboratories, will be allocated time for experiments on a wide array of special instruments, a unique occurrence in France and actually quite rare in the rest of the world, meaning that each potential user can file a request for an experiment with a committee that will review the application and grant (or not) what is called beam time.
BE France - You are a transmission electron microscopy specialist. Where do you use it?
Jérôme Majimel - As a physicist, I joined a chemical laboratory that synthesizes and characterizes materials, tests their properties, and then reviews the syntheses to optimize a specific property. I use transmission electron microscopy that is a tool for characterizing the materials. I would like to add that as I work exclusively on nanomaterials, the common denominator of all the research I am involved in is the nanometer, obviously.
Now I am working on so-called 'nanostructured' materials, mainly applied to two fields, i.e., automotive or domestic pollution control and skin cancer treatment. In the first field, we use rare earth based oxides, mainly cerium, for pollution control. In the second field, we use colloidal gold particles that we synthesize. We give them special morphologies to control the spectral range of their optic response. For instance, by grafting an antibody on the particles so they can latch onto a cancer cell. Once the particles are excited in near infrared, they could destroy the cancer cell by generating local heat.
BE France - When will there be applications in the two fields?
Jérôme Majimel - For automotive pollution control, our research over the past two years with Rhodia will certainly lead to a patent. However, we do not plan for any industrialized products for several years. As for cancer, we are focusing on fundamental research. In other words, the outlook for applications is in the long term.
BE France - Are you planning other developments around transmission electron microscopy?
Jérôme Majimel - The instruments enables us to go "see" what is happening on the nanometer scale. The next step will be to simulate the 'actual' conditions of use of the materials under the microscope beam and observed the engendered modifications. The microscopy already exists in a few laboratories where the influence of temperature, constraints or gaseous environments can be studied. This is a part of microscopy that we are trying to develop in Bordeaux now at ICMCB and CREMEM (Resource Center for Electron Microscopy and Microanalysis), through the high resolution observation of the behavior of nanostructure systems, particularly in a reducer environment.
We have already been able to simulate the mobility of gold atoms on the surface of cerium oxides. The atoms move under the combined effect of temperature rise and oxide reduction. The more they move, the more they can meet and sometimes form "big" clusters larger than 5 nanometers. Beyond this size, gold becomes catalytically inactive. So, we are conducting research to find out what is the oxide area authorizing the smallest movement of gold atoms. Our purpose is to increase the efficiency and life span of the materials used for eliminating carbon monoxide.
