Probe of bending motion following the 1s(-1)pi* excitation of N2O.
The doubly degenerate core-excited Pi state of N2O splits into two due to the static Renner-Teller effect. The lower state, A1, has a bent stable geometry and the molecule excited to this state starts to deform itself toward this bent geometry. To probe the effect of the potential energy surfaces of the core-excited A1 states on the nuclear motion, we measure the momenta of the three atomic ions in coincidence by means of the ion momentum imaging technique. We find that the potential energy surface affects the molecular deformation significantly. N2O in the terminal N 1s(-1)3piA1 excited state is observed to be bent more than that in the central N 1s(-1)3piA1 excited state. This means that N2O in the terminal N 1s(-1)3piA1 excited state bends faster than that in the central N 1s(-1)3piA1 excited state. When the excitation energy is decreased within the 1s(-1)3pi resonances, the nuclear motion in the A1 states becomes faster. This is interpreted by the notion that the excitation occurs onto the steeper slope part of the potential energy surface of the excited state for the lower excitation energy. The branching ratio of the A1 excitation increases with the decrease in the excitation energy.
Dissociation dynamics of core excited N2O
Fragmentation of N2O after selective core excitation of terminal and central nitrogen, has been studied by a multicoincidence technique (PEPIPICO) using synchrotron radiation. We show that dissociation dynamics is dependent upon the excited site, especially in the case of the ‘‘atomization’’ of the molecule. The central nitrogen is always found with very little kinetic energy, except after Nt→Π* transition. A bent intermediate geometry is proposed to explain this observation.
Angular distribution and spin polarisation of Auger electrons
The angular distribution and spin polarisation of Auger electrons following atomic collisions are discussed for the case where both the target atom and the projectile are unpolarised. General expressions for the angular distribution and polarisation of Auger electrons in the (LS)J coupling approximation are obtained and analysed. In the particular case of the p3/2 subshell vacancy the anisotropy coefficient and polarisation are expressed in terms of Auger-decay matrix elements. It is shown that spin-polarised Auger electron spectroscopy of atoms can provide new information on both the Auger process and the structure of atomic hole states, namely, the Auger-decay matrix elements and their relative phaseshifts.