Sur un traitement unifie des deplacements chimiques en spectrometrie photoelectronique de rayons—X (ESCA), des moments dipolaires et des polarisabilites

The simplest and most general model for interpreting ESCA chemical shifts, the physical meaning of which is very clear, also allows the discussion of dipole moments and polarisabilities. Sixty-eight ESCA chemical shifts of C_1s, N_1s, O_1s and F_1s in 41 differently-substituted compounds (?F, ?Cl, ?Br, ?OH, ?NH₂), saturated or unsaturated (aldehydes, ketones, acids), have been calculated with this model from electric charge distribution; the mean quadratic deviations are respectively ±1.1 eV for C, ±1.6 eV for N, ±0.8 eV for 0, ±0.7 eV for F.With this model, electric charge repartitions can be deduced from ESCA data, even for aromatic molecules. The calculated electric dipole moments for 12 fluorinated aromatic molecules agree very well with experimental results. Other data have been calculated for molecules for which experimental data are not yet available, including examples where heavy atoms are present.