Multiplet splitting of core level binding energies in paramagnetic species and the unpaired orbital spin density distribution

The relationship between the multiplet splitting in core electron binding energies of radicals and the unpaired orbital spin density distribution is developed and an explicit formula derived. The atomic intershell exchange interaction is shown to be important to determining magnitudes and trends in the multiplet splitting. The information obtained from an electron spin resonance spectroscopy experiment through the isotropic electron-nuclear hyperfine interaction and an X-ray photoelectron spectroscopy experiment is shown to be complementary.