Spectrum of scandium in the energy region 52 625-54 046 cm-1

The Rydberg and autoionization Rydberg spectrum of scandium via intermediate state [Ar] 3d4s4p F-2(5/2) have been measured in the energy region 52 625-54 046 cm(-1) using two-laser resonance excitation. Four autoionization Rydberg series are observed. Eigenquantum defects mu(alpha) and transformation matrices U-i alpha are calculated from first principles by relativistic multichannel theory within the framework of multichannel quantum defect theory, while the dipole matrix elements D-alpha are obtained by comparing with experimental data. With these parameters mu(alpha), U-i alpha and D-alpha, Rydberg and autoionization Rydberg spectrum of scandium are calculated and the experimental peaks are then clearly assigned. More specifically, one autoionization Rydberg series is converged to Sc+ 3d4s D-3(3), the other three series are converged to Sc+ 3d4s D-1(2), and one autoionization state converging to Sc+ 3d(2)(F-3(2)) and/or Sc+ 3d(2)(D-1(2)) are assigned. In addition, the Fano parameters E-r, q, and Gamma for some of these states are fitted and analyzed.