Soft X-ray irradiation effects in polymer films

Monochromatic synchrotron radiation (250 eV<hv<350eV) has been used to study the core level electronic excitation processes in solid polymer films of PE, PB, PS and PMMA. The electron yield spectra are closely related to the absorption spectra of the polymer surface and reveal characteristic core to valence (Cls→π*) and core to Rydberg (Cls→R) transitions. These excitations, however, do not produce significant bond rupture and ion desorption contrary to excitations induced by photons of energy ≥290 eV. For those energies a significant ion yield is obtained. Possible excitation mechanisms are discussed in detail