Electronic Structures from X-Ray Spectra. II. Mostly ClO3 − and ClO4−

New measurements of the chlorine Kα and Kβ x-ray emission spectra from ClO3 − and ClO4 − ions are reported. The Kα energy shifts give chlorine net 3s, 3p occupations of 5.5 and 4.9 in ClO3 − and ClO4 − respectively. Three lines are observed in the K spectrum of ClO3 −, two in the spectrum of ClO4 −. These emission features are interpreted as transitions from MO's and particular assignments are made. Chlorine 3p contributions to these orbitals are deduced and the ionization-potential differences are estimated. The widths of x-ray spectral features are considered. Evidence is presented which suggests that the argon compound isoelectronic with ClO4 − is unstable; that with ClO3 − is stable. A relationship between heats of formation and x-ray ionization thresholds is discussed.