Development of a pulsed system for ion desorption studies from polymers irradiated with multi-bunch synchrotron radiation

Photon stimulated ion desorption of condensed CO2 at ~ 85 K studied by synchrotron radiation

“…The photon flux was up to 10 13 photons/s and the photon spot size was about 2 x 0.5 mm 2 . The angle of the SR, operating in the multi-bunch mode, with respect to the surface normal was 60 degrees [5]. The results presented here correspond only to the energy range between 93 and 193 eV (2p and 2s Si excitations).…”

Site-selective photofragmentation of chlorinated polymeric films observed around the chlorine K-edge

“…Ion desorption generated by photoexcitation at shallow and deep core levels has already proved to be an attractive topic in surface science since it is a surface phenomena that allows to investigate composition, electronic structure and site-selective fragmentation. Mainly interested in fundamental aspects, our group has performed several previous studies using small chlorinated molecules [5] or polymers, such as poly(vinyl chloride) (PVC) and poly(vinyl dichloride) (PVDC) [6][7][8][9][10], using electrons or high energy photons as excitation sources. In particular, our previous photon stimulated ion desorption (PSID) studies performed on PVC and PVDC films with photon energies covering the valence, Cl 2p and C 1s energy ranges showed element-selectivity as evidenced by an increase in the chlorine ion yield around the Cl 2p-edge as compared to the other excitation energies.…”

“…In the present study, NEXAFS (Near-edge X-ray absorption fine structure) and PSID spectra were acquired at the chlorine 1s-edge for PVC and PVDC, two chlorinated polymers containing a different number of chlorine atoms, in order to gain insight into the photofragmentation process induced by a deep core level, by comparing the contributions from direct (Auger) and indirect (secondary electrons) mechanisms to ionic desorption. Also the purpose of the work is to complement fragmentation studies performed previously on these films covering other energy intervals, ranging from valence to shallow inner-shell excitations [6][7][8][9][10]. The Cl 1s-edge was selected in order to evaluate possible improvements in the site-selectivity fragmentation of the C-Cl bond caused by chlorine core-shell excitation, since it is expected that excitation of localized electrons may favor selective bond breaking.…”