Photon Stimulated Ion Desorption of Polymer Thin Films Following Core Excitation

Abstract

We have studied the photon stimulated ion desorption of poly-isopropenyl-acetate (PiPAc) and poly-vinyl-acetate (PVAc) thin films from the viewpoint of site-specific bond scission. PiPAc is the structural isomer of PMMA, which shows site-specific bond scission. The structures of PiPAc and PVAc are different in the substitutional group of the side-chain, a methyl group or hydrogen. H + , CH + , CH 2 + , CH 3 + and COCH 3 + are mainly desorbed from PiPAc and PVAc thin films following the oxygen core excitation. The near edge X-ray absorption fine structure (NEXAFS) spectra of these thin films are assigned through a comparison to the inner shell electron energy loss spectra of the related molecules. The features of the partial ion yield (Y Pi ) spectra of CH 3 + and COCH 3 + ions are different from that of the total electron yield (Y e ) spectrum. This indicates that the efficiencies of desorption of these ions depend on the primary excitation and these ions are consequently desorbed site-specifically. The most remarkable difference in the Y Pi is seen in the Y Pi (CH 3 + ) and Y Pi (COCH 3 + ) spectra. In Y Pi (CH 3 + ) and Y Pi (COCH 3 + ) spectra, the peak is assigned to the O 1s(C=O) → σ * (C-C) with the help of this result.