Hannover 2016 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

A: Fachverband Atomphysik

A 31: Attosecond physics

A 31.2: Poster

Wednesday, March 2, 2016, 16:30–19:00, Empore Lichthof

Time delay in photoionization with light carrying orbital angular momentum — •Jonas Wätzel and Jamal Berakdar — Institut für Physik, Martin-Luther Universität Halle-Wittenberg, Karl-Freiherr-von-Fritsch-Str. 3, 06120 Halle/Saale

The experiment of Schulze et al. on time delay in photoemission triggered large experimental and theoretical activities with the aim to understand and quantitatively reproduce the results of the measurements. Up to date various mechanisms and calculation techniques were put forward but some differences between theory and experiment remain, calling for further investigation to understand this effect.

To add yet a new aspect to this issue we consider using a twisted light beam, also called optical vortex. Such a beam has a phase singularity at its centre and carries orbital angular momentum (OAM), characterized by the topological charge, which can be transferred to the electron. The usage of OAM light leads to a complete new set of selection rules because the magnetic quantum number m is not preserved and they are directly determined by the choice of the topological charge.

We present results of calculations of the atomic time of the photoionization process of the argon 3p subshell initiated by a twisted light XUV pulse. We show that in different directions either the co-rotating electron (relative to the field) or the counter rotating electron dominates photoionization amplitude. Furthermore the corresponding time delays are completely different. Therefore, the time delay represents an interesting measure to identify the origin of the photoelectron with respect to the initial magnetic (sub-)state.