Anisotropic fragment emission on valence photoionization of CF4

Photoion images from photoionization of CF4 with an isotropic geometry have been measured in the photon energy range of 17-60 eV. Fragment ion emissions below 40 eV are found to be anisotropic with respect to the electric vector of the linearly polarized light. This observation directly implies that the Td symmetry is broken on the dissociative photoionization process. The excited states associated with the transitions to the unoccupied orbitals are subject to symmetry lowering, which promotes the anisotropic fragment emissions from the highly-symmetrical molecule.