Effects of molecular conformation on inner-shell ionization energies.

Experimental evidence for an effect of molecular conformation on inner-shell ionization energies has been observed for the first time. Examples are seen in the carbon 1s spectra of butyronitrile, 1-fluoropropane, and propanal, and other similar molecules. At room temperature these exist in two different conformations, with different distances and, hence, different Coulombic interactions between the negatively charged electronegative group and the methyl carbon. The experimental results are in accord with theoretical predictions with respect to both ionization energies and populations of the different conformers.