Research

At the Max Planck Institute for Solid State Research (MPI-FKF), we develop instrumentation to transfer molecules from a solution to a surface under ultra-high vacuum, after mass selection and soft deposition of the ions, in order to image them one by one by scanning tunneling microscopy.

My work focuses more specifically on the instrumental development of the apparatus, in particular the electrospray source, the ion optics, and the interfacing of the instrumentation.

For an overview of the group's scientific activity: anggara.science.

This work aimed at a better understanding of atmospheric oxidation processes by proton transfer reaction mass spectrometry (PTR-MS). It led me to develop the instrumentation, the experimental protocols and the data processing tools necessary to study highly reactive and weakly concentrated systems, notably in work published in JACS Au.

The massive production of data by this new experimental device, on the order of 1 GB per hour of experiment, required the development of a complete data processing program, written in the Julia language.

This tool, MassSpec.jl, is fully open-source and constitutes a robust basis for the analysis of complex atmospheric measurements and the direct detection of reactive intermediates. The project is available here: gitlab.com/massspec.jl/MassSpec.jl.

Unlike conventional devices, this reactor operates in continuous regime and without moving parts. I also developed a variant allowing the residence time to be modulated by the flow rate, by means of a buffer arm.

Beyond gas-phase measurements, this approach enables direct quantitative measurements of rate constants and uptake rates at gas–solid or gas–liquid interfaces. It thus paves the way for quantitative measurements on surfaces that are difficult to study with conventional architectures.

These measurement campaigns focused on gaseous and particulate emissions, as well as their oxidative aging. They showed that gaseous emissions can lead to the formation of secondary particles, with a direct impact on air quality, as shown in ES&T Air.

This part illustrates the value of instrumental developments designed first for fundamental research, then reused in concrete environmental contexts.

At the Institut de Physique de Rennes, I worked on CRESUSOL, an instrument coupling a uniform supersonic flow in a Laval nozzle (CRESU) with a time-of-flight mass spectrometer in photoelectron–photoion coincidence (TOFMS-PEPICO). The objective was to study the molecular growth of neutral aggregates and reactions between neutral species in conditions of interest for astrochemistry.

This work belongs both to instrumental development and to the study of fundamental gas-phase mechanisms at very low temperature. A description of CRESUSOL is available in Review of Scientific Instruments.

The exponential decays observed when monitoring radicals do not necessarily reflect chemical reactivity. In many cases, they are mainly explained by density drop effects related to the mixing of gases in Laval nozzle flows.

This new interpretation sheds light on the fact that rate coefficients measured at very low temperature have often been overestimated. It is at the heart of my critical re-reading of the field, notably in the commentary Commentary Regarding the CRESU-SIS Experiment.

This tool makes it possible to design nozzles adapted to the desired conditions of temperature, density and gas flow rate, in order to maximize the uniformity of the expansion. It has been made publicly available and is a useful tool for the community working on CRESU experiments.

The program is available here: odurif.gitlab.io/cresu.