Name: Per Johnsson
Date of birth: 22 November 1978
2002: MSc in Engineering Physics, Lund University, Sweden
2006: PhD in atomic physics, Lund University, Sweden
2006-2008: Postdoctoral fellow at the FOM Institute for Atomic and Molecular Physics, Amsterdam, the Netherlands
Associate professor in Physics, Atomic Physics Division, Lund University, Sweden
I completed my Master of Science in Engineering Physics at the Lund University in Sweden with a partly experimental Master’s project on femtosecond laser pulse shaping. Through this project, I got a glimpse of ultrafast experimental physics with lasers, and wanted more.
Thus, I decided to stay as a PhD student in the field. My PhD project involved the generation, characterization and application of attosecond pulses. During my time as a PhD student we built up the attosecond laboratory at the Lund High-Power Laser Facility where, at that time, the shortest attosecond pulses in the world were generated in 2003.
Following this I spent two years as a postdoctoral fellow at the FOM Institute for Atomic and Molecular Physics (AMOLF) in Amsterdam, switching gears by changing my previous focus on electron dynamics in atoms to electron dynamics in molecules. In Amsterdam we designed and built up an attosecond pump-probe setup as well as a velocity map imaging spectrometer tailored for experiments on attosecond dynamics in molecules. The main effort during my postdoctoral time was however to initiate, plan and coordinate an experimental programme at the free electron laser (FEL) in Hamburg (FLASH), aiming to study structural dynamics in molecules using novel pump-probe techniques together with photoelectron diffraction and interference in XUV photionization of laser-aligned molecules.
In 2009 I returned to Sweden and Lund University for a position as a Research Associate. In the years that followed I received two national grants which made it possible for me to start building my own research group, and in 2013 I got a qualification as Associate Professor in Physics, and obtained a position as University Lecturer.
The aim of my current research is to perform combined imaging of charge localization and molecular structure, seeking to study the interplay between electron dynamics and changes in the molecular structure. Currently, my group focuses on experiments carried out at the high-intensity HHG beamline of the Terawatt laser system at the Lund High-Power Facility. Intense efforts on beamline development during the last few years, as well as an expansion of the laboratory, have led to an optimized HHG source where, at the moment, harmonic pulse energies in the microjoule range can be achieved, and where we have recently managed to observe two-photon double ionization of neon, indicative of intensities in the range needed for realizing XUV pump-XUV probe experiments.
My group collaborates with the groups of Anne L’Huillier, Mathieu Gisselbrecht and Johan Mauritsson within the Lund Attosecond Science Centre (LASC), with a broad approach to attosecond physics in different systems, e.g. atoms, molecules, surfaces and clusters. In addition to the high-intensity HHG beamline mentioned above, LASC routinely operates sources of attosecond pulse trains at 1 kHz and uses them for attosecond physics, e.g. in interferometric measurements of photoemission time delays. The latest addition to LASC is an optical parametric chirped pulse amplification (OPCPA) system delivering few-cycle CEP-stable laser pulses at 200 kHz. These pulses are used to drive an HHG attosecond source ideal for experiments requiring low peak powers and high repetition rates, e.g. surface studies and applications with detection based on coincidence techniques.