Experimental and theoretical study of the C-1s shakeup spectra from biphenyl and p-terphenyl

The experimental and theoretical C-1s shakeup spectra of biphenyl and p-terphenyl have been studied by means of high resolution X-ray photoelectron spectroscopy (XPS) and the intermediate neglect of differential overlap configuration interaction (INDO/CI) method. It is found that the spectra of the two molecules arise from two types of excitations, those that redistribute charge within one phenyl ring, and those that move charge from one phenyl group to another. The latter charge transfer disappears as the conjugation between the phenyl planes is broken (by rotation) and the spectrum becomes identical to that of benzene.