Study On Autoionization Spectra Of Rare Earth Atoms And Applied Spectra

Spectroscopy has always been an important branch of physics.It can not only study the excitation kinetics of atoms or molecules,but also be applied to the analysis of material composition.In this paper,atomic absorption spectroscopy（AAS）,fiber optics reflectance spectroscopy（FORS）and laser-induced breakdown spectroscopy（LIBS）are applied,and the following studies were carried out from the two aspects of atomic spectrum and applied spectrum:Firstly,Sm and Eu atomic autoionization spectra and Stark effect were studied.Because the 4f shell of Sm atom is not half filled,its energy level structure is extremely complex.If both the outermost two electrons are excited and the sum of the energies of the two electrons exceeds the ionization energy of a single electron,the autoionization process will occur.At this time,the autoionization state and the continuous state will interact,resulting in an asymmetric Fano line spectrum of the autoionization state.To study this complex process,rare earth Sm and Eu atoms were selected.Because the Sm atom has a half-filled 4f shell,its energy level is very complex.For example,the lowest electron configuration 4f⁶6s² also has 7 child energy levels.In this paper,a Sm atom was excited from the ground state 4f⁶6s² 7F₀ to 4f⁶6s（⁸S）np autoionization state by multi-step resonance excitation and polarization combination technique.The energy level positions,linewidths and asymmetry factors of 13 self-ionization states were obtained.The relative strength ratios of the autoionization transitions under different polarization combinations were also studied.We further studied the autoionization spectra of Eu atoms at zero field and at 400-2000 V·cm-1 strong electric field,and not only obtained the relevant information of the autoionization states,but also studied the Stark effects of the autoionization states,such as movement,broadening and splitting.Secondly,in addition to the atomic spectrum,this paper also involves the applied spectrum,the absorption spectrum and the diffuse reflection spectrum of organic and inorganic Chinese painting pigments.The diffuse reflectance spectra of organic pigments gamboge and rouge,inorganic pigments mineral yellow（S type）and ochre（S type）,azurite（bell type）and malachite（bell type）,and ochre（S type）and malachite（bell type）were obtained by using FORS.At the same time,the derivative spectrum method and multiple linear regression method were used to analyze the diffuse reflection spectrum and absorption spectrum of mixed pigments with different proportions.The method of unmixing based on FORS technology is proposed for the first time,which is of great significance to the nondestructive analysis of Chinese painting pigments.Finally,in order to solve the problem of accurate unmixing of mixed pigments,this paper also explores the identification and calibration of material components by LIBS.Taking oxygen-free copper as an example,the Libs spectra in the range of 300-950 nm were obtained,and the atomic and ion lines of the metal Cu element were calibrated.This has laid a solid foundation for using LIBS technology to study the composition and semi-quantitative analysis of Chinese painting pigments.In short,this paper has carried out in-depth studies on rare earth atoms,oxygen-free copper and Chinese painting pigments by different spectroscopic means,which has made some valuable work for the in-depth understanding of the basic principles of physics and the practical application of spectroscopy.