Probe of bending motion following the 1s[–1]π* excitation of N2O

The doubly degenerate core-excitedΠ 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]3πA1 excited state is observed to be bent more than that in the central N 1s[–1]3πA1 excited state. This means that N2O in the terminal N 1s[–1]3πA1 excited state bends faster than that in the central N 1s[–1]3πA1 excited state. When the excitation energy is decreased within the 1s[–1]3π 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. ©2004 American Institute of Physics

Dissociation dynamic of multiplycharged ions after core excitation

We interpret PEPIPICO spectra obtained on N2O excited in the K shell of nitrogen and on ICN excited in the 4d and 3d shell of iodine. The analysis of dissociation dynamics leads to the conclusion that Coulomb explosion is invalid in both case. The anisotropy of ions ejection after nitrogen K shell excitation of N2O molecule can be explained by Auger relaxation and subsequent dissociation of the molecule being faster than rotation. The results of triple coincidence (PE3PICO) reveal that the dissociation dynamic of trication are different than dication

Core excitation in atomic and molecular clusters

Core level excitation, ionization, and fragmentation of homogeneous and heterogeneous atomic and molecular clusters is reported. Size and composition dependent properties of free clusters are derived. Total electron yields and partial cation yields are used for detection of spectroscopic changes as a function of cluster size. Photoionization of variable size and composition clusters is investigated by zero kinetic energy (ZEKE) photoelectron spectroscopy. Photoelectron-photoionphotoion- coincidence (PËPIPICO) spectroscopy is applied for determination of size dependent fragmentation mechanisms of doubly charged clusters. Argon and nitrogen are investigated as model systems. The results are compared to corresponding investigations of the isolated gas phase species and the condensed phase