Anisotropic ultrafast dissociation probed by the doppler effect in resonant photoemission from CF₄

The symmetry lowering of the highly symmetric spherical top molecule CF₄ that belongs to the T_d point group, to the C_3v symmetrical top, caused by the F1s excitation was discussed. As such, the Doppler splitting of the F1s^-1 atomiclike Auger line was observed. Since the shift arises from nuclear motion before Auger decay takes place and fragmentation was initiated on the excited-state potential energy surface, this phenomenon constitutes direct proof that the asymmetric nuclear motion proceeds in the F 1s-excited state, along the direction of the polarization vector of the incident light, leading to symmetry lowering from T_d to C_3v.