Doctoral position: How do shallow convective clouds change the oxidation capacity of the troposphere?

The Max Planck Institute for Chemistry in Mainz offers a doctoral position in atmospheric chemistry, starting in September 2026. The position is located in the Atmospheric Chemistry Department (Prof. Eric Kort) in the group of Dr Hartwig Harder. The project will be jointly supervised by Prof. Eric Kort and Dr. Hartwig Harder.

The project

Biogenic and anthropogenic emissions rise from the surface with moist air and form shallow convective clouds. At the cloud top, reflected ultraviolet radiation speeds up the photochemistry, and with it the production of the radicals OH and HO₂. The cloud droplets, in turn, take up soluble compounds, process them in the liquid phase and release them again when the droplets evaporate. How much these two processes change the oxidation capacity of the atmosphere is an open question. Answering it is the aim of this thesis. Both in the chamber and on the aircraft, you will measure OH and HO₂ by laser-induced fluorescence (LIF), operating the instrument yourself. The work has three parts:

• Chamber experiments at CERN (2026). In the CLOUD chamber you will investigate, under controlled conditions, how liquid water droplets change the OH and HO₂ chemistry, with glyoxal and isoprene as test compounds.
• Aircraft measurements with HALO (2027/2028). During the COTANGO campaign, based in Argentina, you will probe the air below, in and above shallow convective clouds: over land with strong isoprene emissions, and over the ocean, where there is little.
• Satellite data and global modelling. With the group of Dr. Andrea Pozzer you will combine satellite cloud statistics with the EMAC model to estimate what the measured effects mean globally.

Your profile

• A master's degree (or equivalent) in physics, physical chemistry, atmospheric science or a related field, completed by the start of the position.
• A strong background in physics. The LIF instrument is a laser system with optics, detectors and vacuum components, and you will run it yourself.
• Interest in atmospheric chemistry and in laboratory and field work.
• Experience with lasers, optics, spectroscopy, data analysis or programming (for example Python) is helpful.
• Willingness to travel for the campaigns at CERN and abroad.
• Good written and spoken English; German is not required.

Our offer

The position is funded for three years. The salary follows the collective agreement for the German public service (TVöD Bund), pay group E13 (65 %), with the usual public sector benefits, according to the rules of the Max Planck Society. You will work in an international team and within two large collaborations, CERN CLOUD and HALO COTANGO. Doctoral training and participation in international conferences are part of the programme.

How to apply

Please send your application as a single PDF file (letter of motivation, CV, certificates and transcripts, and the names and contact details of two academic referees) by 15 September 2026 by e-mail to Hartwig.Harder@mpic.de. Later applications will be considered until the position is filled. For questions about the position, please contact Dr. Hartwig Harder (Hartwig.Harder@mpic.de).

About the Max Planck Institute for Chemistry

The Max Planck Institute for Chemistry (Otto Hahn Institute) in Mainz conducts fundamental research on the chemistry of the Earth system. It studies the interactions between the atmosphere, biosphere, land and ocean and their role in air quality and climate. The institute is one of more than 80 research institutions of the Max Planck Society, Germany's leading organisation for basic research.

Equal opportunity

The Max Planck Society strives for gender and diversity equality and welcomes applications from all backgrounds. The Max Planck Society has set itself the goal of employing more severely disabled people. Applications from severely disabled people are expressly welcome. The Max Planck Society seeks to increase the proportion of women in areas in which they are underrepresented. Women are therefore expressly encouraged to apply.

By submitting your application, you agree that your personal data may be processed and stored for the purpose of the selection procedure in accordance with the applicable data protection regulations.