We investigate fundamental properties of atomic and molecular negative ions. The main motivation for the research is that the relative importance of the theoretically interesting electron correlation effect is enhanced in negative ions. The normally dominant Coulomb interaction between each electron and the core is therefore suppressed. Under such conditions the independent particle model, that adequately describes atomic structure under normal conditions, breaks down. Experimental studies of negative ions can therefore serve as a probe of electron correlation and hence be used to test theoretical models that go beyond the independent electron approximation. The interest for negative ions has increased significantly during the last few years after the discovery of several molecular negative ions in the interstellar media. The main part of our experimental work is conducted at Göteborg University Negative Ion Laser LAboratory (GUNILLA). We gain information about these ions by studing the photodetachment process, in which a negative ion is neutralized due to the absorbtion of a photon. Current research interest involve doubly excited states, the double detachment process and fundamental properties of negative ions of astrophysical interest.
We are also working with an application of negative ions with the goal to improve the detection limits in Accelerator Mass Spectrometry (AMS). This is the most sensitive method for trace element analysis, where detection of 14C is the most well know example. The research aims to develop a method where photodetachment in an ion cooler can be used to suppress interfering isobars that otherwise would prevent detection of very rare isotopes. This work is conducted in collaboration with research groups in Mainz in Germany, Vienna in Austria, and at Oak Ridge National Laboratories in the US.
The group is also involved in research on negative ions at several other laboratories. Core excitations are studied at the Advanced Light Source at Berkeley and lifetimes of excited states in negatives ions are investigated at the storage rings at the Manne Siegbahn Laboratory/Stockholm University. Interactions between negative ions in high intensity fields are investigated using femtosecond lasers are studied at Freiburg university.
The group is also involved in some projects outside atomic and molecular physics. We are currently building an experimental system for investigating the collective ordering in complex systems of microscopic rod-like objects suspended in a liquid with a random flow. This is visualized using light of different wavelengths at different incoming angles. A microfluidic system is also designed using lithographic methods to study the motions of single rod-like objects under the influence of a shear flow. The microscopic particles are produced in the lab and studied using microscopic methods. These studies aim to increase the understanding of complex systems and particle interaction with a viscous media.