Electric Field Ionization Process Of Eu 4f~76snp Rydberg States

The field ionization process of the Eu atomic 4f76 snp Rydberg series, converging to the first ionization limit 4f76 s 9S4,is systematically investigated. Firstly,the spectra of the Rydberg states 4f76 snp of Eu atom are measured using the three-step laser excitation and electric field ionization(EFI) method. Secondly, two different types of field ionization pulse are applied respectively after laser excitation. The exact location of ionization threshold can be obtained when the peak of ionization field changes. Above the threshold some structures are found due to black body radiation(BBR) driving the atom to lower states. In addition, the ionization signal falls down suddenly in specific ionization field. Finally,the field ionization relationship is acquired.Except the two different kinds of the EFI pulses,another different kinds of the EFI pulses are applied after laser excitation to observe the possible impacts on the EFI process. The field ionization process of the Eu 4f76 snp Rydberg states,converging to the first ionization limit,4f76 s 9S4, is systematically investigated in different PW. The EFI spectra in different PW can be determined for the 4f76 snp Rydberg states. Especially,the field ionization process of the Eu 4f76 snp Rydberg states,in PW 0.2μs,is systematically investigated.The field ionization process of the Sm Rydberg states is investigated. Spectra of bound highly excited states of the Sm atom, have been studied with stepwise excitation and EFI detection method.In brief,the field ionization process of the Eu and Sm is systematically investigated. The spectra of the Eu 4f76 snp Rydberg states are populated with three-step laser excitation,and detected by EFI method. Different kinds of the EFI pulses are applied after laser excitation to observe the possible impacts on the EFI process. In addition, the ionization signal falls down suddenly in specific ionization field. Especially,some structures above the EFI threshold are found in the EFI spectra,which may be interpreted as the effect from black body radiation(BBR). Finally,the scaling law of the EFI threshold for the Eu 4f76 snp Rydberg states with the effective quantum number is built. For the first time we get the EFI spectra of the Sm. The investigation not only enriches the spectral information of Eu and Sm atoms,but also provides a lot of important information to many engineering fields.