Measurements On Radiative Parameters Of Au I Levels

At present,in astrophysics,the chemical composition of stars and the determination of the relative abundance of elements are important theoretical foundations for studying the age,evolutionary process and energy source of stars.Spectral analysis of a large number of high-resolution celestial spectra obtained by various ground-based telescopes and space telescopes is one of the current methods for scientists to determine the chemical composition of stars and the relative abundance of their elements.Atomic radiative parameters are one of the most important data for spectral analysis,including natural radiative lifetimes,branching fractions,transition probabilities and oscillator strengths.In recent years,with the acquisition of a large number of high-resolution and high-signal-to-noise celestial spectra,it has been found that many chemically exotic stars are rich in heavy metal elements such as Au,Pt,and Hg.Therefore,obtaining atomic radiative parameter data for these heavy metals is particularly important.Although many researchers have measured the natural radiative lifetime and oscillator strength of these heavy metal atomic levels.But for gold atoms(Au I),the lifetime and oscillator results are not enough for the data needed for spectral analysis.To the best of our knowledge,the results of natural radiative lifetime on Au I determined by experimental methods are currently only 15 levels and the oscillator strength are only five lines.Therefore,natural radiative lifetimes of ten levels between 37358.991 and 58616.764 cm~-11 on Au I were measured by time-resolved laser-induced fluorescence technique,six of them were reported for the first time.The measured lifetimes range from 6.8 to 965 ns,and the error is within 10%.In addition,branching fractions(BFs)of 15 lines for eight of these levels were determined by the emission spectrum of a hollow cathode lamp.The transition probabilities and oscillator strengths of these lines were derived by combining the BFs with lifetime values.These experimental results are not only the basic data needed for the improvement of celestial spectral analysis,but also have important reference significance for the study of plasma diagnosis,laser physics and the nonconservation of wave function parity.