Resonances close to the first ionization threshold of antimony

Even-parity Rydberg and autoionizing Rydberg spectrum of antimony have been calculated by relativistic multichannel theory, in which the ionic core dipole polarization effect due to the Rydberg electron has been included. Combining reanalysis of the experimental spectra via different intermediate states, (Formula presented.) and (Formula presented.) some perturbers below the first ionization threshold which are corresponding to the lower-lying members of Rydberg series converging to higher thresholds are found and identified as well as these reported perturbers. Some Rydberg states are reclassified and all observed autoionizing resonances are identified. Moreover, the reason why linewidths of autoionizing peaks span one orders of magnitude is because two closely spaced autoionizing states result in the apparent isolated broad peak while autoionizing resonances associated with (Formula presented.) orbitals have narrow linewidths.