Open Positions
Open Positions
Doctoral students
We currently have two positions available: Position 1 and Position 2.
Both positions will focus on the investigation and control of charge carrier dynamics in nanostructures on the low femtosecond time scale. This is a highly topical research field combining a number of techniques. Accordingly, a high level of motivation to get involved in new topics is expected, but not extensive prior knowledge in these specific fields. Rather, creativity and a quick grasp of the subject are helpful in finding one's way in this field of research. Intensive supervision is ensured by the size of the group and the nature of the project.
The first PhD project in the framework of the Emmy Noether program is about using a photoemission electron microscope to follow charge carrier dynamics on the nanoscale with the highest temporal resolution. For this purpose, laser pulses in the low femtosecond to attosecond range are generated and used in the electron microscope to excite and probe a sample. The possible applications here are as diverse as the skills learned in this project. The goal is to establish a microscopy method with unprecedented temporal resolution.
The second PhD project within the Landesgraduiertenkolleg "DyNano" will deal with the generation of attosecond pulses by means of few-cycle laser pulses controlled in their spectral amplitude and phase. In collaboration with the group of Matthias Wollenhaupt, we want to better understand the generation process of high harmonics and to characterize the attosecond pulses specifically generated in it on the one hand and to use them for the photoemission of electrons from nanostructures on the other hand. The goal here is also to gain insight into ultrafast charge carrier dynamics on the nanoscale.
Theses (Bachelor or Master)
Overview
Students who would like to write their thesis with us are of course very welcome.
In general, there are many smaller and larger projects that can be worked on within the framework of the construction of the new attosecond laboratory and the time-resolved photoemission electron microscope. Previous experience is not necessary; however, an interest in learning new things and actively tackling challenges is certainly advantageous. From femtosecond laser systems to vacuum systems, from attosecond pulses in the ultraviolet to electron microscopy, a wide variety of techniques can be tried out and used to investigate charge transfer processes in nanostructures. We work closely with other physics groups and use the attosecond laboratory of the UNO and ULTRA groups until our own laboratory is fully functional.
Project 1: Control of attosecond pulses
Currently, there is an opportunity for a Master's student (or a particularly ambitious Bachelor's student) to get directly involved in cutting-edge research on the control of attosecond pulses. These are (among) the shortest light flashes ever produced and the aim is to better understand their generation. For this purpose, light pulses in the visible spectral range are manipulated with only a few oscillations of the electric field, so that the attosecond pulses thus generated acquire desired properties. Adjusting screws here are, for example, the polarisation of the light and the oscillation amplitude in time. Control of these attosecond flashes is relevant in order to better understand electronic processes on the shortest time scales.
Project 2: Time-resolved photoemission electron microscopy
This Bachelor's or Master's project is about putting a recently procured electron microscope into operation and initially characterising it with regard to its specified parameters. In the second step, it is planned to carry out the first time-resolved experiment on such a microscope in Oldenburg, whereby the exact research question and sample to be investigated will be determined during the first part of the project in consultation with the candidate.
Photoemission electron microscopy is somewhat different from conventional microscopy techniques. In this case, the sample is also the electron source, in that electrons are triggered from it - by illumination with light. These trigger sites are imaged in the microscope with high spatial resolution. At the same time, the time of flight of the electrons is recorded so that their kinetic energy spectrum can also be measured. This allows detailed insights into the charge carrier dynamics near the surface of a nanostructure.
A variety of techniques will be introduced to you in this project, including sample preparation, nanopositioning systems, ultra-high vacuum, electron microscopy, time-of-flight electron spectroscopy and excitation-interrogation experiments with short laser pulses. This project, like many in this group, is rather challenging but offers the opportunity to learn a lot through close collaboration with group members.
Project 3: Generation and characterisation of ultrashort laser pulses in the near infrared
This project forms part of the basis for the future work of the junior research group Attosecond Microscopy. We are currently building a laser system that uses nonlinear processes to generate ultrashort laser pulses in the infrared spectral range. However, these pulses are not (quite) short enough for the planned experiments. There are several approaches to shorten light pulses by spectral broadening and subsequent temporal compression to such an extent that they last only a few oscillations of the electric field. The aim of this project is to further compress laser pulses at a central wavelength of 2 µm and a pulse duration of about 30 fs by focusing them into thin glass plates and to characterize them with respect to their pulse duration, beam quality and power stability. Intensive on-site supervision is ensured (don't worry!), and an exchange with colleagues in Lund (Sweden) is possible at the same time.
And what happens next?
Feel free to contact us if there is something for you in the proposed projects. And feel free to contact us even if no project appeals to you directly. Sometimes we come up with spontaneous project ideas or a project seems different after we've done a little lab tour.
We are generally happy if you bring this with you:
- A solid physics background
- An interest in learning new things
- Fun in working in the laser lab
In return, you will receive, among other things:
- Intensive supervision, support for the whole group
- the opportunity to try out many new devices and techniques
- first own research results
- an exciting final project
Please contact us briefly. :)
Post-doctoral researchers
There is the possibility of financing a postdoc position in our group. At the same time, an application to third-party funders to finance your own position would be desirable.
If you are interested, please contact us and we can discuss the possibilities. A short email is enough!
