Postdoc position: Controlling splashing and debris from solidifying tin droplets

Our group combines precision experiments, advanced imaging, and modeling to uncover the physics of tin droplets under extreme conditions of laser irradiation. We have established a strong track record in laser-droplet interaction, droplet deformation, and fragmentation physics. Our recently published works include laser-driven sheet formation and propulsion, curvature inversion in thin films, transitions between droplet oscillation and breakup, and singular jetting in free-falling droplets [e.g. J. Fluid Mech. 1020, A21 (2025); J. Fluid Mech. 1034, A26 (2026); Phys. Rev. Fluids 11, 073602 (2026)].

This project builds directly on that expertise to uncover how rapid solidification governs splashing, adhesion, and debris formation when molten-tin droplets impact solid substrates.

Background

Molten droplets impacting colder surfaces are encountered in applications ranging from EUV lithography to metal additive manufacturing and droplet-based printing. During impact, inertial spreading, capillary retraction, heat transfer, and solidification can occur on comparable timescales. Depending on impact conditions and surface properties, the droplet may adhere, rebound, splash, freeze, peel from the surface after solidification, or break up into smaller secondary droplets.

Although droplet splashing and solidification during impact have each received substantial attention, their strongly coupled dynamics under reduced ambient pressure remain insufficiently understood. Establishing which physical mechanisms, dimensionless parameters, and scaling laws remain valid across these scales is therefore both a fundamental and technologically relevant problem.

Project goal

The project aims to develop a predictive, experimentally grounded understanding of how rapid solidification and ambient pressure shape molten-tin droplet impacts, and to use this insight to identify surfaces and operating conditions that minimize splashing and debris formation. You will start from a droplet-on-demand platform for millimeter-sized molten-tin droplets, with systematic control over ambient pressure, substrate temperature, impact velocity, and surface properties, combined with synchronized high-speed side- and bottom-view imaging.

You will establish quantitative regime maps for spreading, sticking, rebound, freezing, peeling, and fragmentation. Using existing image-analysis tools and newly developed workflows, you will quantify droplet deformation, contact-line motion, solidification dynamics, and the size and velocity distributions of secondary droplets. These measurements will form the basis for predictive scaling relations that describe fragment formation across pressure and temperature conditions.

Together with collaborators at TU/e and UvA, and through interaction with industrial partners, you will translate the resulting physical understanding into practical design principles for low-debris surfaces and operating windows in advanced EUV source environments.

Qualifications

• You have (or will soon obtain) a PhD in (Applied) Physics, Mechanical Engineering, Chemical Engineering, Materials Science, or a closely related field.
• You have a strong experimental background and enjoy designing, building, and improving laboratory experiments.
• Experience in one or more of the following areas is an asset: fluid dynamics, droplet impact, multiphase flow, heat transfer, phase change, high-speed imaging, vacuum systems, optical diagnostics, or surface science.
• Experience with scientific programming and quantitative data analysis, particularly in Python, is welcomed.
• Experience with droplet generation, thermal diagnostics, image processing, or automated experimental control would be advantageous, but is not required.
• Strong verbal and written communication skills in English are required, together with enthusiasm for collaborative, hands-on research.
• You are motivated to take scientific ownership of the project, from experimental design and quantitative analysis to physical interpretation and publication.

Work environment

The Advanced Research Center for Nanolithography (ARCNL) focuses on the fundamental physics and chemistry involved in current and future key technologies in nanolithography, primarily for the semiconductor industry. ARCNL is a public-private partnership between the Dutch Research Council (NWO), the University of Amsterdam (UvA), Vrije Universiteit Amsterdam (VU), the University of Groningen (UG), and the semiconductor equipment manufacturer ASML. ARCNL is located at Amsterdam Science Park in the Netherlands and has approximately 100 scientists of which 65 are ambitious (young) researchers from all over the globe and support staff. See also www.arcnl.nl

Working conditions

The position is intended as full-time (40 hrs / week, 12 months / year) appointment in the service of the Netherlands Foundation for Scientific Research Institutes (NWO-I) for the duration of 2 years, with a starting salary of €4,552 gross per month, scale 10 (CAO-OI), and a range of employment benefits. A favorable tax agreement, the ‘30% ruling’, may apply to non-Dutch applicants. ARCNL assists any new foreign researchers with housing, subject to availability, and visa applications and compensates their transport costs and furnishing expenses.

Other conditions offered by ARCNL:

• Responsibility for a dedicated molten-tin droplet-impact setup with controlled ambient pressure and substrate temperature.
• The opportunity to obtain publishable results on a millimeter-scale droplet-on-demand platform whose design is workshop-ready.
• Hands-on work with high-speed imaging, vacuum technology, precision diagnostics, and surface-controlled impact experiments.
• A central role in designing and executing experimental campaigns and in developing quantitative fate maps for bouncing, sticking, peeling, and fragmentation.
• Rich image and time-resolved data sets, with scope to develop advanced analysis workflows in Python.
• Close scientific collaboration with researchers in fluid mechanics, theory, and numerical simulation at ARCNL, TU/e, and UvA.
• Possibility to enhance your experimental research work with advanced numerical simulations of complex fluid flows.
• Direct interaction with industrial partners and the opportunity to translate fundamental physics into contamination-mitigation strategies.
• A highly interdisciplinary environment spanning multiphase flow, laser-matter interaction, plasma physics, surface science, and nanolithography.

More information?

For further information about the position, please contact:

Dr. Oscar Versolato

Group leader EUV Plasma Processes

E-mail: versolato@arcnl.nl

Phone: +31 (0)20-851 7100

Application

You can respond to this vacancy online via the button below.

Please send your:

• Resume
• Motivation letter on why you want to join the group and this project (max. 1 page).

Online screening may be part of the selection.

Diversity code

ARCNL is highly committed to an inclusive and diverse work environment: we want to develop talent and creativity by bringing together people from different backgrounds and cultures. We recruit and select on the basis of competencies and talents. We strongly encourage anyone with the right qualifications to apply for the vacancy, regardless of age, gender, origin, sexual orientation or physical ability.

Commercial activities in response to this ad are not appreciated.