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.
Intra-molecular H2+ formation in the core-excited HCCH probed by multiple-ion coincidence momentum imaging
Abstract In the HCCH molecule, H2+ ions have been produced only at the 1s→π* excitation, suggesting that the H2+ ion formation is mediated by the core excitation. The nuclear motion in the C 1s−1π* core-excited state is probed using a multiple-ion-coincidence imaging technique and the enhanced cis bending motion is found by examining the H–H correlation angle distributions. The H2+ formation is thus attributed to the cis bending motion caused in the C 1s−1π* state.
Near threshold excitation of KVV Auger spectra in carbon monoxide using electron-electron coincidence spectroscopy
Electron–electron coincidence spectroscopy has been used to separate KVV Auger spectra in CO into several component spectra, each arising from different core‐excited initial states. Results are presented for the Auger decay of ions in which either a carbon 1s or oxygen 1s electron has been ionized and for the decay of neutral molecules in which either a carbon 1s or oxygen 1s electron has been excited to the vacant 2π orbital. The spectra from the neutral molecules have been studied and analyzed in some detail. These autoionization spectra can be broken into two parts. The highest kinetic energy part where the 2π electron participates in the decay is easily understood; in this case, the Auger transitions lead to well‐known one‐hole states of CO+. The lower‐energy part arises from deexcitation with the 2π electron remaining as a spectator. This part of the spectrum is similar to the ‘‘normal’’ Auger spectrum shifted approximately 10 eV by the Coulomb interaction with the spectator electron. The similarity ...