Study Of Radiative Parameters Of Nb?and Hyperfine Structure Of Nb?,Nb?,Au?and Au?

The radiative parameters and hyperfine structure data for levels of atomic ion have important applications in the study of celestial spectral analysis and atomic physics.In the field of celestial spectral analysis,reliable radiative parameters such as transition probability and oscillator strength are important to determine the chemical abundance of elements.When determining the element abundance,if the hyperfine structure(HFS)and isotope shift(IS)of spectral lines were taken into account,the result could be more accurate.In the field of atomic physics,reliable radiative parameters can be used to verify the results of atomic theoretical calculation,while accurate hyperfine structure data can help to improve the accuracy of atomic theoretical calculation and the study of nuclear physical properties.Although the radiative parameters of some levels of niobium ions have been obtained by various experimental methods,there are still some problems such as lack of data and large uncertainties of previous data,and there are few reports on the hyperfine structure constants of niobium ions and gold ions.The transition probability and oscillator strength can be determined reliably by combining the radiative lifetimes and branching fractions.In this paper,the radiative lifetime of Nb ? level was measured by time-resolved laser-induced fluorescence(TR-LIF)method.Lifetimes of some Nb ? highly excited states are calculated using the pseudo-relativistic Hartree-Fock method including core-polarization contributions(HFR+CPOL)and the fully relativistic multiconfiguration Dirac-Hartree-Fock(MCDHF)method.Combining the experimental radiative lifetime with the theoretical branching fraction calculated by HFR+CPOL method,the semi-empirical transition probability and oscillator strength values were determined.In this paper,Fourier transform spectra of Nb and Au hollow cathode lamps from the database of the National Solar Observatory(NSO)in USA were used to analyze the hyperfine structure of Nb I,Nb ?,Au I and Au ? spectra,and the hyperfine structure constants were determined.This paper carried out and completed three parts of the work,as follows:1.The radiative lifetimes of 34 levels of Nb ? were determined by TR-LIF method,and the theoretical lifetimes of these levels were calculated by HFR+CPOL and MCDHF method.Theoretical branching fractions,transition probabilities and oscillator strengths of 389 spectral lines related to these levels were calculated by HFR+CPOL method.The transition probabilities and oscillator strengths of these lines were determined by combining the measured lifetimes with the calculated branching fractions.As far as we know,for the 34 levels studied in this work,the radiative lifetimes of 30 of them were reported for the first time,the uncertainties of most of the results are less than 10 %,the results of the other 4 levels are in good agreement with previous results.The branching fraction,transition probability and oscillator strength values of 296 lines were determined for the first time.2.In this paper,13 Fourier transform spectra of gold hollow cathode lamps obtained from the database of NSO in USA were analyzed,and the hyperfine structure of the Au I and Au ? spectral lines were analyzed.The hyperfine structure constants of 19 Au I levels and 6 Au ? levels were determined.For Au I,the uncertainties of most of the results are less than 20 %,and for Au ?,the uncertainties of most of the results are less than 50 %.As far as we know,among them,the HFS constants of 22 levels were not reported.For the results of three levels reported in the literature,our results are in good agreement with previous results.3.Nine Fourier transform spectra of niobium hollow cathode lamps obtained from the database of NSO in USA were analyzed.Hyperfine structure of 155 Nb I and Nb ? spectra lines was analyzed,and the hyperfine structure constants of 68 Nb I and 57 Nb ? levels were determined.As far as we know,the hyperfine structure constants of 26 and 46 levels were measured for the first time,and the uncertainties of most of the results are less than 10 %.For the levels reported in the literature,our results are in good agreement with previous experimental results.Hyperfine structure constants of 323 Nb I levels and 53 Nb ? levels have been reported in previous literature.For Nb I with 411 known levels,our results will enrich the atomic database.For Nb ? with 353 known levels,our results nearly double the number of the level with known HFS constant values.In this paper,the radiative parameters of some Nb ? highly excited levels were determined,and the hyperfine structure constants of many Nb I,Nb ?,Au I and Au ? levels were determined,which has greatly enriched the atomic structure and spectral database of neutral and singly-ionized niobium as well as neutral and singly-ionized gold.These data will be of scientific and applied value in astrophysics,atomic physics and plasma physics.