Artigo de Periódico
Site-selective photofragmentation of chlorinated polymeric films observed around the chlorine K-edge
Fecha
2013Registro en:
0301-0104
v. 415
Autor
Arantes, C.
Mendes, L. A. V.
Pinho, R. R.
Ferreira, M.
Souza, Gerardo Gerson Bezerra de
Rocha, A. B.
Rocco, M. L. M.
Arantes, C.
Mendes, L. A. V.
Pinho, R. R.
Ferreira, M.
Souza, Gerardo Gerson Bezerra de
Rocha, A. B.
Rocco, M. L. M.
Institución
Resumen
Photon stimulated ion desorption (PSID) and Near-edge X-ray absorption fine structure (NEXAFS) studies
have been performed on poly(vinyl chloride) (PVC) and poly(vinyl dichloride) (PVDC) around the chlorine
1s-edge. Experiments were performed using a synchrotron source operating in the single-bunch mode
and a time-of-flight mass spectrometry for ion analysis. Cl+ ion yields, as a function of the photon energy,
reproduce the photoabsorption spectrum, showing significant increase at the 1s-resonance. Edge-jump
ratios, defined as the ratio between edge-jumps (intensity ratio of the yields between above and below
the absorption edge) of two different transitions, for Cl+ ion yields were much higher than the equivalent
electron yields, indicating site-selectivity in C–Cl bond breaking for both polymers, as a result of efficient
spectator Auger decay. The expected isotope ratio of 3:1 for chlorine was measured for PVC. The interpretation
of the NEXAFS spectrum was assisted by quantum mechanical calculations at a multireference perturbation
theory level.