Ionic fragmentation of CF4 in the vacuum ultraviolet through the soft X-ray region Original Research Article

Fragment ions from the irradiation of CF4 with photons in the soft X-ray region (44–1500 eV) have been measured using a time-of-flight mass spectrometer and monochromatized synchrotron radiation. Yield ratios have been obtained for the positive ions resulting from CF4 over this energy range as have the yield ratios of the positive ion pairs formed in the C K-edge and the F K-edge regions. Yield ratios of F+C+, and CF+ increase and the yield ratio of CF3+ decreases significantly with increasing photon energy below the C K-shell excitation energy and exhibit discontinuities at the C K-edge and F K-edge. At the C K- and the F K-shell excited states, CF4 dissociates to yield more C+ ions than that at the core ionization. The new channels from CF4 dissociating to the ion-pair of F+-CF+2 and F+-CF+3 open up at the F K-edge but not at the C K-edge, suggesting site specific fragmentations. Dissociation pathways of CF4 around the C K-edge and F K-edge are discussed on the basis of the yield ratios of fragment ions and ion-pair productions.