Investigations On Radiative Parameters Of Odd-Parity Highly Excited Levels Of Lr I

In recent years,with the development of astronomical observational technique,a large number of astronomical spectra with high resolution and signal-to-noise ratio were observed.The spectral lines of some heavy metal elements?Lu,Os,Pt,Au and Ir,etc.?were acquired in metal-poor stars and chemical special stars,which promoted the understanding of the abundance,evolution and composition of elements in such celestial bodies.Astronomical spectroscopy is an astrophysics study process that determines the chemical composition of a celestial body,the abundance of elements,and physical quantities such as celestial bodies,pressure,and gravity,by studying the spectral properties of celestial bodies.Atomic radiative parameters are important data in spectrum analysis,including natural radiative lifetimes,branching fractions,transition probabilities and oscillator strengths.However,studies on radiative parameters of heavy metal elements is rarely reporeted.In this paper,the radiative parameters for neutral iridium?Ir I,Z=77?are experimentally measured and theoretically calculated.Radiative lifetimes of odd-parity levels for Ir I were measured using the time-resolved laser-induced fluorescence?TR-LIF?technique.In the experiment,free atoms were obtained by laser-induced plasma technique,Ir I polulated in lower energy levels can be selectively excited the aim energy levels,and then the fluorescence detection system was used to observe and collect the fluorescence decay signal.The lifetime values were obtained by exponential or deconvolution fitting.Radiative lifetimes of 62odd-parity levels of Ir I in the energy range between 32513.43 and 58625.10 cm^-1were measured.The lifetime values obtained are in the range from 3.2 to 345 ns.To our best knowledge,59 results are reported for the first time.These are compared to computed data deduced from a pseudo-relativistic Hartree-Fock model including core-polarization contributions.From the combination of the experimental lifetime measurements and branching fraction calculations,a new set of transition probabilities and oscillator strengths is derived for 134 Ir I spectral lines of astrophysical interest in the wavelength region from 205 to 418 nm.In a word,the atomic data measured in this paper are not only important in celestial spectral analysis,but also have important scientific and application value in the field of atomic physics,plasma physics and nuclear reaction process?...