Tomographic Atom Probe and Optical specTroscopy: a couplEd appRoach – TAPOTER

The main goal of this project is the development of a new instrument coupling the capabilities of Atom Probe Tomography (APT) and optical spectroscopy, in particular photoluminescence and absorption spectroscopy. The main ambition is to answer to open questions about the physics of ultrafast laser-matter interaction. Furthermore, we aim to develop an instrument which could represent a paradigm for the next generation of atom probes. Atom probe tomography consists in the controlled field ion emission (or “evaporation”) of the atoms of a tip with a nanometric apex radius, immerged in a high electric field. In the latest generation of instruments, this process is triggered by a femtosecond laser pulse. The evaporated ions are detected by a position- and time-of-flight-sensitive detector, which allows for the reconstruction of the chemical composition of the nano-object in 3D. This technique still presents a certain number of open questions, especially concerning the complex laser-matter interaction mechanisms and the physics of field ion emission under ultrafast laser pulse. The absorption mechanisms in insulators, the relaxation of the absorbed energy following the pulse, the dynamics of surface atoms are some examples of the problems requiring a systematic investigation. Moreover, the laser-matter interaction and the evaporation behavior significantly depend on the shape and composition of the studied object, and this may introduce a certain number of aberrations in the trajectories of evaporated ions, which sometimes limit the accuracy of the reconstruction of the original position of the atoms in the sample. Despite these limitations, APT is a technique for nanoscale analysis reaching even beyond the 3D reconstruction.
For these reasons, this project proposes to develop new instrumental tools in order to study more in depth the mechanisms of interaction between a fs laser pulse and a nanometric object placed inside a strong electric field (i.e. a field emission tip). The method is based on:
(i) The study of selected model systems such as semiconductor quantum emitters and metal nanoparticles embedded in a dielectric matrix, under the form of field emission tips.
(ii) A complementary analysis of the mechanisms of optical absorption and emission, as well as of ion field emission, performed simultaneously on the same nano-object.
These goals can only be achieved through a preliminary phase of instrumental development. It is indeed necessary to integrate within an atom probe setup all the elements allowing for the optical absorption and emission spectroscopy of a nanometric tip.
The primary interest of this project is fundamental, as it focuses on the study of physical phenomena at the nanoscale in conditions (high electric field, ultrafast laser pulse) which have not been systematically addressed yet. The method proposed for this study, based on the coupling of state-of-the-art optical and structural analytical techniques, has never been proposed by other research teams before. The results we expect to obtain will provide a new insight not only in the domain of field ion emission, but also in the domain of the physics and technology of nanostructured systems such as semiconductor nanowires or metal nanoparticles. Finally, the technical know-how acquired by the team in the instrumental development phase can be valorized in terms of intellectual property through the filing of patents.
The achievement of the goals of the project are based on the joint competences of the project coordinator (PC) Lorenzo Rigutti, and of the instrumentation team (ERIS) of the Groupe de Physique des Matériaux of the University of Rouen, which he recently joined (September 2012) as a lecturer.