Correlation between core level chemical shifts obtained by ultrasoft x-ray emission and ESCA

High resolution C:K X-ray emission spectra have been recorded from six molecules in the gas phase. The spectra are interpreted by comparing the relative X-ray energies with the vertical ionization energies of the valence orbitals and comparing the intensities predicted by the C 2p populations from CNDO calculations with the measured intensities. The obtained C 1s binding energy shifts are found to be in excellent agreement with shifts measured with ESCA.