Investigation Of Auger And Interatomic Coulumbic Decay

With an inner hole electron ionized,the hole-state atom can relax through electronic decay.Auger and interatomic coulombic decay(ICD)are electronic decay irriated by electron correlation.In thin environment,the study of Auger decay is based on isolated atom theory.In denser environment,where the environment effect is non-negligible,ICD can be an efficient charge redistribution process.This thesis mainly studied electronic decay of the Auger,double Auger and ICD processes.The specific work are as following.Firstly,the complete Auger decay of Rb⁺(3d^-1)including single and double pro-cesses was investigated using the distorted wave approximation.The direct double Auger decay was calculated by separating the knock-out and shake-off mechanisms.For sin-gle Auger decay of the 3d^-1hole state,it is generally believed that the dominant chan-nels should be levels belonging to the configurations of 4s²4 p⁴5s,4s4 p⁵5s and 4s⁰4 p⁶5s.However,the calculated results indicate that the strongest channels originate from 4s²4 p³4d5s,which accounts for 36.3%of the single Auger decay rate.The levels belonging to this configuration can further decay to Rb³⁺,resulting in a large fraction of cascade dou-ble Auger decay.Moreover,the probability of direct double Auger decay in Rb is also high because of its 5s electron.The branching ratios of cascade and direct double Auger decay are predicted to be 50.60%and 22.13%,respectively,resulting in the dominance of double Auger decay with a fraction of 72.73%in the complete Auger decay of Rb⁺(3d^-1).Moreover,this work investigated the core-level ICD of Xe⁺(4d^-1)-R(R=Xe,Kr,Ar)and Kr⁺(3d^-1)Kr,and ulteriorly studied competition between the local Auger decay and core-level ICD processes.The local Auger decay widths stays almost constant with different interatomic distances.However,the efficiency of ICD is strongly increased with decreasing interatomic distance and decreasing energy transfer in the decay step,and influenced by the character of the neighboring atoms.The ICD-to-Auger ratio in the Franck-Condon region,where the decay occurs,is at most 0.26%.However,it reaches a few percentage points in larger clusters and becomes amenable for experimental ob-servation.The small value of the branching ratio is due to large interatomic distances in the dimers(4–4.4(?)).The calculated results also indicate,in accordance with previous measurements,that in hydrogen-bonded and microsolvated clusters,where the distances between the monomers are 2–3(?),core-level ICD should become an important pathway for charge redistribution following the absorption of hard x-rays.In consideration of the importance and effect of electron impact ionization cross section in ICD and direct double Auger decay,the detailed electron impact single ion-ization cross sections of Se³⁺are theoretically investigated using a detailed level-to-level distorted-wave formalism.The ionization cross sections of the two levels belonging to the configuration of([Ni])4s²4 p are nearly equivalent and so are 4s²4d,whereas large difference is found for the levels of 4s4p².The theoretical results can be utilized to ana-lyze and interpret an experimental measurement for the single-ionization cross section of S e³⁺(Alna'washi et al.,2014).The population distributions existed in this experiment are deduced.Except for the levels of the ground configuration,there exist populations from levels of the excited configuration of 4s²4d.