Calculations of the Energy of the Triplet 5sns(³S₁), 5snd(³D_1,2) and the Singlet 5snd(¹D₂) States of the Rydberg Series of the Strontium Atom Using the Screening Constants Per Unit Nuclear Charge Method

   We report calculations of accurate high-lying resonance energies of the triplet and the singlet states of the Strontium Rydberg series. Calculations are performed using the Screening Constant by Unit Nuclear Charge (SCUNC) method from n = 12 to 60. This semi-empirical method is widely used in atomic physics to predict energies of excited states without requiring calculation of photoionization cross-sections. Present results are compared with the existing NIST database of Kramidal and Advanced Light Source measurements of Couturier et al. Analysis of the present results is achieved in the framework of the standard quantum-defect theory of the SCUNC procedure. In addition, the present work demonstrates the strength of the SCUNC formalism to assist experimenters in the analysis of measurements.

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