Radiative lifetimes of bound excited states in anions : Measurements on long-lived metastable states in atomic anions

Abstract: This thesis presents and discusses the results of measurements of the intrinsic lifetimes of bound excited anionic states. The results are valuable for evaluation of different theoretical models and computation methods and are compared to calculations when available. The measurements were carried out at the DESIREE facility located in the AlbaNova University Center in Stockholm. The storage ring used is cryogenically cooled and has a very low residual gas density. Both of these features are needed for the storage of some bound excited anionic states, as blackbody radiation would otherwise photodetach the state. Residual gas density is the main limiting factor for storage lifetime in the presented measurements. The majority of the work has been in the development and refinement of the laser probing technique utilized for the measurements, which had to be adapted for each anion to account for the different time-domains and wavelengths required.The published results was a radiative lifetime of 503±54 seconds for the 3p5 2P1/2 state in sulfur, 15.1±0.4 seconds for the 4s2 2D3/2 state in nickel and 2.54±0.10 seconds for the 5d10 6s 2S1/2 state in platinum. The radiative lifetime of the 5d9 6s2 2D3/2 state in platinum could only be estimated to a range of 50 ms to 200 ms.