Energy Level Analyses Of Odd-and Even-parity J=1, 2 Rydberg Series Of Sn I By Multichannel Quantum Defect Theory

The atomic Rydberg states have received considerable attention for a long time in atomic physics and laser spectroscopy. Neutral tin(Sn I, Z = 50), which belongs to carbon group elements, can be characterized by a 5s25p2 ground configuration and possesses a p-electron ion core with a highly excited nl electron in its Rydberg states. In fact, the electronic structure of Sn I have been investigated extensively. Brill and Wilson reported many energy levels for Sn I by analyzing the arc spectrum and the absorption spectrum, respectively. Later, Brown et al investigated the high-resolution absorption spectrum of Sn I. Using a two-step laser excitation technique, Nadeem et al investigated numerous even-parity Rydberg levels and they analyzed 5pnp J = 2 and 5pnf J = 2 series by MQDT method in the frame of three- and two-channel models, respectively. Meanwhile, many even-parity Rydberg levels were also determined by Jin et al using the resonant multiphoton ionization and the time-of-flight mass spectroscopy methods. Not only that, there were many investigations on the theoretical side. The perturbations from 5s5p3 configuration have been investigated by Dembczynski et al using pseudo-relativistic Hartree-Fock (HFR) ab-initio calculations. The J = 3 energy levels of the odd-parity in Sn I were analyzed by Ginter et al using the perturbed coupled-channel models in the frame of MQDT. Later on, Robicheaux et al carried out the R-matrix calculations for the properties of odd-parity J = 0–3 bound levels in Sn I.To our best knowledge, Brown et al analysed odd-parity Rydberg series by MQDT method, but they didn't discussed the results in detail and also didn't predict the new levels which haven't been measured by experiment methods. Meanwhile, systematic MQDT analysis for even-parity Rydberg levels of Sn I has not yet been reported in the literature since the energy level data were just published recently.For the reasons above, it is necessary and interesting to investigate the Rydberg series of Sn I by means of MQDT method in order to understand the configuration interaction characteristics and to supplement theoretical energy level data for the incomplete experimental results reported in the literature.In this paper, using the published data in literature, we analysed the odd- and even-parity J = 1, 2 Rydberg series of Sn I in detail by MQDT method. First, the odd-parity J = 1 and 2 Rydberg series of Sn I have been analysed with the MQDT method both in five-channel model. Using the nonlinear minimization method, the optimal MQDT parameters of two series were obtained and the corresponding Lu-Fano plots were also shown in this paper. A total of 42 new energy levels with J = 1 and 62 new levels with J = 2 were determined based on the present calculations, the RMS results for J = 1, 2 series have been provided. Comparing the MQDT results to the HFR results calculated by Dembczynski et al, we corrected Brown's assignments of 50125.97 and 57283.66 cm–1. Meanwhile, considering the data from Moore and Brown, we discussed the uncertain assignments of 51010.94 and 53631.83 cm–1 in J =2 series. Then, the pertubations from every pertubers to Rydberg series were analysed in detail.The even-parity J = 1 and 2 Rydberg series of Sn I have been analysed with the MQDT method in five- and six-channel models, respectively. The optimal MQDT parameters together with the corresponding Lu-Fano plots were present. Total 85 new energy levels with J = 1 and 23 new levels with J = 2 were determined based on the present calculations, and RMS results were also calculated. The doubtful 5p5f (3/2,5/2)2 level whose difference between the calculated and measured values was too large has been analysed. In Moore's table, for some levels assignment of J values were uncertain, the level assigned as 5p3/24f J = 2 by Moore was confirmed by the present MQDT analyses. Then, the interchannel interactions in even-parity were anaysed in detail. Meanwhile, the predicted levels with several uncertain levels call for corresponding experimental verification.The above results are helpful to understanding of the configuration interaction characteristics of odd- and even-parity J = 1, 2 Rydberg series of Sn I, and provide important data for atomic physics and laser spectroscopy field.