Experimental examination of ionization processes of noble gases in strong laser fields [Elektronische Ressource] / vorgelegt von Rolf Wiehle

Experimental Examinationof Ionization Processesof Noble Gasesin Strong Laser FieldsInaugural-DissertationZur Erlangung des Doktorgrades derFakult at fur? Mathematik und PhysikAlbert Ludwigs Universit at, Freiburgvorgelegt vonRolf WiehleMarch 7, 2005Dekan: Prof. Dr. J. HonerkampErstgutachter: Prof. Dr. H. HelmZweitgutachter: Prof. Dr. M. Weidemuller?Datum der mundlic? hen Prufung:? 24.02.2005AbstractThis thesis discusses experimental results on the interaction of intense light withisolated atoms. Inside the focus of modern pulsed lasers, electric fields are pro-duced, which are comparable with the atomic field strength. The correspondinghigh number of photons available, allows the ionization of noble gas atoms byabsorption of a great number of IR-photons, whose individual energy is muchsmaller than the atom’s ionization potential. Alternatively, the interaction maybe described in terms of fields: The laser modifies the binding potential, sup-pressing the Coulomb barrier, such that an electron may tunnel out.Theoreticalcalculationsforsingleionizationwereabletoreproduceexperimentalresults, but strong deviations were observed for double ionization. The rescatter-ing model was invented which accounts for many of the previously unexplainedfeaturesfoundinexperiments. Withinthismodelthefirstelectronisfreedbythelaser and subsequently accelerated in its oscillating electric field. Upon return toitsparention,theelectroninteractswithitandfreesasecondelectron.