Dynamical model of nuclear motion in the Auger emission spectrum of the core-excited [Formula Presented] molecule

Nuclear motion of a plane polyatomic molecule [Formula Presented] is theoretically investigated under the core excitation of the B [Formula Presented] electron to the antibonding [Formula Presented] unoccupied molecular orbital. The B atom starts to move in the direction out of plane immediately after the core excitation. Owing to the finite core-hole lifetime comparable to a vibrational period, the B atom can move around the new equilibrium position of the core-excited state and the Auger decay occurs while this nuclear motion is going on. The x-ray absorption spectra and the resonant Auger emission spectra are calculated quantum mechanically. The calculated results are in reasonable agreement with the recent experimental results, illustrating that the dynamical aspect in the nuclear motion in the core-excited state is directly reflected in the resonant Auger emission spectrum.