Spin-orbit time delays in photoemission of noble gases

Photoionization is a fundamental light-matter interaction traditionally described as an instantaneous process. However, modern attosecond spectroscopy has shown that electron emission occurs on finite timescales that can be experimentally resolved. In this thesis, photoionization time delays in noble gas atoms are investigated with particular emphasis on delays between spin-orbit-split electronic states. Such fine-structure splitting arises from spin-orbit coupling and provides a sensitive probe of electron dynamics and many- body interactions in atoms. The experiments were performed at the Attohallen attosecond facility at the University of Gothenburg. Intense few-cycle femtosecond pulses generated by an OPCPA laser sys- tem were used to drive high-harmonic generation in a noble gas target, producing extreme ultraviolet attosecond pulse trains. These pulses were combined with a synchronized near-infrared probe field in a Mach-Zehnder interferometer and analysed using the Recon- struction of Attosecond Beating By Interference of Two-photon Transitions (RABBIT) technique. Photoelectron spectra were recorded with a 5.5 m magnetic bottle electron spectrometer, enabling high collection efficiency and improved spectral resolution. The work demonstrates the reproduction of attosecond pulse train generation and the implementation of spin-orbit-resolved RABBIT measurements. By analysing delay- dependent sideband oscillations in the photoelectron spectrum, temporal information about the photoionization process can be extracted. The results contribute to ongoing efforts to improve the precision of attosecond delay measurements and provide insight into the role of spin-orbit interaction in ultrafast photoemission dynamics.