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Research Zernike (ZIAM) Quantum Interactions and Structural Dynamics Schlathölter Group

MSc and BSc projects

There are always exciting opportunities for talented Master and Bachelor students in our team. Below, you find two example MSc projects, currently available. More MSc and BSc projects with similar focus are always possible. For more information, please contact Thomas Schlathölter.

MSC project 2021 – Multiple electron detachment Auger decay in single DNA molecules
Inner shell excitation/ionization (top) and subsequent single and multiple electron Auger de-excitation (bottom)
Inner shell excitation/ionization (top) and subsequent single and multiple electron Auger de-excitation (bottom)

One of the most fundamental processes underlying radiotherapy is the radiation-induced production of low energy electrons in biological systems. These electrons in turn are responsible for a very large part of the biological damage, in particular to cellular DNA.

In our group we have recently shown that X-rays as well as (therapeutically relevant) MeV ions both lead to removal of several electrons in single collisions with isolated DNA molecules. This is a very surprising result, as the underlying interaction process is inner-shell excitation or ionization. The induced inner-shell vacancy then decays by a so-called Auger process in which most of the excitation energy was expected to be released in the form of kinetic energy of a single emitted Auger electron. Our results indicate that in this process at least 3 electrons are emitted, which has fundamental implications for our understanding of biological radiation damage.

In this project, you will use our gas-phase biomolecule apparatus to prepare targets of synthetic DNA anions in a radiofrequency ion trap. During an experimental campaign at the SOLEIL synchrotron in Orsay, you will directly measure the Auger electrons emitted after X-ray interactions with these trapped DNA anions.

MSc project 2021: Hydrogenation of N-substituted PAHs
PAHs in space
PAHs in space

Molecular hydrogen is the most abundant molecule of our Universe. H2 formation on Polycyclic Aromatic Hydrocarbon (PAH) cations is considered a potentially important route towards molecular hydrogen formation in the interstellar medium (ISM). Hydrogen interaction with PAHs furthermore is a model system for hydrogen-graphene interactions, the latter being key for future graphene-based hydrogen storage appliactions.

We have recently found that for coronene cations (C24H12 +), sequential H attachment involves well defined adsorption sites. Along this sequence, "magic numbers" of attached H atoms are observed to be particularly stable [1]. The process competes with H2 abstraction, where an incoming H atom reacts with a previously attached H atom, to form a free H2 molecule.

Until now, attachment and abstraction reactions have only been studied for genuine polycyclic aromatic hydrocarboncations. In this project, the process will be investigated systems where single C atoms are substituted by N. These systems are relevant from an astrobiological point of view, as they could be a template for formation of prebiotic molecules in astrophysical environments.

[1] S. Cazaux, L. Boschman, N. Rougeau, G. Reitsma, R. Hoekstra, D. Teillet-Billy, S. Morisset, M. Spaans & T. Schlathölter, Nature Scientific Reports 6 (2016) 19835

MSc projects: Soft X-ray and heavy ion interactions with gas-phase DNA
Our RF ion-trap at the FLASH facility in Hamburg
Our RF ion-trap at the FLASH facility in Hamburg

The concept of radiotherapy for tumor control is based on the idea of killing cancerous cells by means of ionizing radiation, while simultaneously sparing healthy surrounding tissues. This implies delivery of high doses to tumour volumes while minimising dose deposition into surrounding healthy tissues. To increase the contrast between dose to tumor and healthy tissue so-called radiosensitizers are enriched in the tumor. Heavy metal nanoparticles are the most recent group of radiosensitizers, for which the clinical potential is currently investigated. Currently, the underlying mechanisms on a molecular level are not fully understood for X-ray irradiation and even more ambiguous for proton or heavy ion therapy. The investigation of this issue in macroscopic systems (in vivo and in vitro) is difficult because of the complexity of the systems and because timescales range from the fs-scale of primary ionization and excitation processes over ms timescales of diffusion limited radical chemistry up to second and even year timescales of biological processes and biological endpoints.

In our group, we are investigating the most fundamental processes of radiation action on DNA on a molecular level, i.e. on sub-nanometer length-scales and on few femtosecond time-scales. In the course of this project, you will use a radiofrequency ion trap, to prepare a well defined target of gas-phase DNA ions. You will then study the interaction of soft X-rays with these targets during an experimental campaign (typically two weeks) either at the synchrotron BESSY II (Berlin) or SOLEIL (Paris).

Last modified:06 July 2021 5.11 p.m.