Abstract
Three Rydberg series, n s, n p, and n d, converging to the 2E1/2 and 2Φ1/2 states of CH3I+ and HI+, respectively, are identified on the basis of their photoionization spectra. Splittings observed in the Rydberg peaks of CH3I are attributed to an interaction of the Rydberg electron with the quadrupole moment and polarization of the ionic core. Three one‐electron wavefunctions for the Rydberg orbital were investigated to determine the effect of the quadrupole moment on the Rydberg energy levels.