Hyperfine Structure Constants And Isotope Shifts Of Neutral And Singly Ionized Europium

When modern high resolution spectroscopy is used to study atomic spectra,it can be found that many atomic spectra show hyrefined structure,which is caused by the interaction between electric moment,magnetic moment and electron of nucleus.The measurement of isotope shift(IS)and hyfine structure(HFS)in atomic and ion spectra is of great application value to atomic and nuclear physics.They provide important information about the internal structure of atoms,the shape and magnetic moment of nuclei,and the spatial distribution of current and charge in nuclei.At the same time,with the improvement of spectral resolution of celestial bodies,people gradually realize the importance of hyperfine splitting,isotope displacement and other physical effects in astrophysics.The HFS and IS of levels lead to the widening and asymmetry of the spectral line profile.If these factors are ignored,the measurement of the position and intensity of the spectral line will be inaccurate.Therefore,the HFS constants and the IS data of atomic and ion levels are crucial for the analysis of celestial chemical composition and element abundance.In recent years,the HFS constants and IS of europium atom(Eu I)and europium univalent ion(Eu II)levels have been studied experimentally and theoretically.So far,190 HFS constants of Eu I level and 337 transition lines IS have been reported.And16 Eu II level HFS constants and 28 transition lines IS.According to the NIST atomic spectroscopy database,592 levels of Eu I and 163 levels of Eu II have been found.Therefore,there are still many HFS of Eu I and Eu II levels to be studied,which is of great significance to the study of HFS constants and IS of Eu I and Eu II levels.In this paper,the Fourier transform(FT)spectra from the National Solar Observatory database(https://nso.edu/data/historical-archive/)are fitted and analyzed by the HFS spectral analysis program based on the least square method and HFS principle.The HFS constants of 29 energy levels and IS of 30 transition lines for Eu I between 17707.42 and 47373.10 cm^-1 are determined.The HFS constants of 22energy levels and IS of 24 transition lines are determined for the first time.In addition,the HFS constants of 15 levels and IS of 19 transition lines are determined for Eu II between 1669.21 and 56271.40 cm^-1,of which the HFS constants of 8 levels and IS of8 transition lines are not reported in the literature.For the HFS constants with 7 Eu I and 7 Eu II levels reported in the literature,the results obtained in this paper are in good agreement with those reported by others within the error range.For the HFS constants of Eu I and Eu II levels and IS determined in this paper,most of the results are within 10%error.In this paper,HFS constants and IS data of Eu I and Eu II levels are well extended,which has important scientific reference value for scientific research in the fields of atomic physics,nuclear physics and astrophysics.