Applications are invited for a PhD fellowship/scholarship at Graduate School of Natural Sciences, Aarhus University, Denmark, within the Chemistry programme. The position is available from August 2025 or later.

Title:
Molecular diffusion in atmospheric aerosol particles: sensing oxygen in aerosols with luminescence indicators

Research area and project description:
Organic aerosols, nano-to micro-meter sized particles suspended in air, are ubiquitous in Earth’s atmosphere. These aerosols are key drivers for atmospheric chemistry, air pollution and climate. In order to predict the large-scale impacts of these particles, fundamental knowledge on their (small-scale) physicochemical properties is crucial. A key property in this regard is the molecular diffusion of oxidants, organic molecules, water and gases such as carbon dioxide (CO₂) and oxygen (O₂). For example, the equilibrium partitioning of O₂ from the surrounding gas phase and its availability within the particle can affect reactions inside the particle and hence its composition. Molecular diffusion in organic particles is inversely related to the dynamic viscosity of the aerosol particles, which for atmospheric organic aerosol can vary over many orders of magnitude, depending on the ambient conditions.

This project aims to probe the diffusion into and the availability of O₂ in organic aerosol particles. We will develop fluorescence microscopy-based methods, where the transport and abundance of O₂ within particles can be determined using luminescence indicators. A focus of this work will be to test the formation of hypoxic (O₂-lack) and anoxic (O₂-absence) in relation to the particle viscosity. We will investigate organic standards used as proxies for atmospheric aerosol. In addition, we will also investigate realistic secondary organic aerosol that will be generated in our advanced atmospheric simulation chamber (AURA). The envisioned experimental research will provide important information for atmospheric transport models used to estimate e.g., aerosol-borne transport of pollutants.

To address this exciting task, we are looking for a curious and highly motivated PhD student, to join our team.

This experimental PhD project will be hosted at the Aerosol and Cloud Microphysics group in collaboration with the Single Molecule Biophysical Chemistry group at the Chemistry Department and iNano center of Aarhus University. The candidate will also be part of the Center for Chemistry of Clouds (C3, chem.au.dk/forskning/forskningscentre-og-projekter/c3) and have access to the Aarhus Single Molecule Fluorescence (AsiMoF, www.asimof.au.dk) infrastructure. Both Chemistry and iNano provide an inclusive, collaborative and interdisciplinary working environment and provide access to premier experimental research infrastructure, laboratories and access to shared equipment.

Assist. Prof. Fabian Mahrt will be the direct supervisor and Prof. Victoria Birkedal will be the formal supervisor.

In order to assess if you are well qualified for the position, we strongly encourage you to contact Fabian Mahrt or Victoria Birkedal, prior to submitting a formal application

For technical reasons, you must upload a project description. When - as here - you apply for a specific project, please simply copy the project description above, and upload it as a PDF in the application. If you wish to, you can indicate an URL where further information can be found.

Qualifications and specific competences:
Applicants to the PhD position must have a finished Master’s degree, or a finished Bachelor´s degree plus one year of Master´s studies completed (at the time of starting the position), within Chemistry, Physics, Atmospheric Science, Nanoscience, Engineering or similar.

See website for Graduate School of Natural Sciences for more details on 5+3 vs. 4+4 PhD degree structures: phd.nat.au.dk/for-applicants/phd-study-structure-and-income

The successful candidate has demonstrated excellent academic results, is committed to integrate into a driving and collaborative environment and must have excellent English language and communication skills (written and oral).
Prior experience with instrumentation to probe aerosols or handling of other instrumentation relevant to this project such as microscopes is an advantage. The candidate must have good collaboration skills and at the same time be able to take responsibility and work independently on their project.

Place of employment and place of work:
The place of employment is Aarhus University, and the place of work is Department of Chemistry, Langelandsgade 140, 8000 Aarhus C, Denmark. 

Contacts:
Applicants seeking further information for this project are invited to contact:
Prof. Victoria Birkedal, vicb@inano.au.dk

Assist. Prof. Fabian Mahrt, mahrt@chem.au.dk
How to apply:

For information about application requirements and mandatory attachments, please see the Application guide. Please read the Application guide thoroughly before applying.

When ready to apply, go to https://phd.nat.au.dk/for-applicants/apply-here/ (Note, the online application system opens 1 March 2025)

1. Choose May 2025 Call with deadline 1 May 2025 at 23:59 CEST.
2. You will be directed to the call and must choose the programme “Chemistry”.
3. In the boxed named “Study”: In the dropdown menu, please choose: “Molecular diffusion in atmospheric aerosol particles: sensing oxygen in aerosols with luminescence indicators (Mdaaps)”

Please note:

• The programme committee may request further information or invite the applicant to attend an interview.

At the Faculty of Natural Science at Aarhus University, we strive to support our scientific staff in their career development. We focus on competency development and career clarification and want to make your opportunities transparent. On our website, you can find information on all types of scientific positions, as well as the entry criteria we use when assessing candidates. You can also read more about how we can assist you in your career planning and development.

Aarhus University’s ambition is to be an attractive and inspiring workplace for all and to foster a culture in which each individual has opportunities to thrive, achieve and develop. We view equality and diversity as assets, and we welcome all applicants. All interested candidates are encouraged to apply, regardless of their personal background.