Ionic desorption from intrinsically conducting polymer films based on polypyrrole induced by high energy electrons and soft X-ray synchrotron radiation

Ionic desorption from polypyrrole films doped with dodecylsulfate as counter anion (PPyDS) deposited onto fluorine tin oxide glass (FTO) was studied through electron (ESID) and photon (PSID) stimulated ion desorption techniques, employing time-of-flight mass spectrometry (TOF-MS) for ion analysis. ESID results suggested strong contribution from DS fragments to the mass spectra. In the 650-1500 eV energy range the relative desorption ion yield curves show maxima at about 700, 1200 and 1400 eV, which may be related to carbon, nitrogen and oxygen containing fragments, respectively, and interpreted in terms of the Auger stimulated ion desorption (ASID) mechanism. For energies greater than 1500 eV, the secondary electrons play an important role in the ion formation. PSID studies were performed at the Brazilian Synchrotron Light Source (LNLS) covering the sulphur K-shell photoexcitation during a single-bunch operation mode of the storage ring. Ionic desorption of atomic and molecular fragments were also observed. Relative desorption ion yield curves have been determined as a function of the photon energy, indicating that at the photon energy region covered by the PSID studies the indirect XESD (X-ray induced electron stimulated desorption) process plays an important role in the ionic desorption of PPyDS irradiated by soft X-rays.