The experimental photoabsorption spectrum and photoionization spectrum of 2-butyne from Refs. 25 and 6, respectively. Also shown is the theoretical photoionization spectrum from the present work.
(a) The reconstructed photoelectron image following single-photon ionization of 2-butyne at 10.320 eV. (b) The angle-integrated photoelectron kinetic energy spectrum extracted from the reconstructed image.
The angle-integrated photoelectron kinetic energy spectra extracted from the photoelectron images recorded following single-photon ionization at several different photon energies. (a) 9.739 eV, (b) 9.835 eV, (c) 9.933 eV, and (d) 10.347 eV. For these spectra, the electron energy and ionization potential have been subtracted from the photon energy, and the x axis gives the internal energy of the photoion.
The experimental and theoretical β2 values for the near-threshold, single-photon ionization of 2-butyne. The experimental β2 values are plotted separately for ionic final states with v2 + = 0 and 1. The error bars for the v2 + = 0 and 1 values are smaller than the symbol diameters; however, these error bars only represent the counting statistics and do not include systematic effects. The theoretical curve has been displaced to lower energy by 0.411 eV, which corresponds to the shift between the experimental and theoretical resonance maxima in the cross section data of Figure 1.
(a) The reconstructed photoelectron image following two-photon ionization with a photon energy of 4.967 eV (the two-photon energy is 9.933 eV). (b) The corresponding angle-integrated photoelectron kinetic energy distribution.
(a) The reconstructed photoelectron image following two-photon ionization with a photon energy of 4.870 eV (the two-photon energy is 9.739 eV). (b) The corresponding angle-integrated photoelectron kinetic energy distribution.
Representations of the highest occupied and lowest unoccupied orbitals (HOMO and LUMO, respectively) for acetylene, propyne, 1-butyne, and 2-butyne. For 1-butyne, the higher energy orbital plotted is actually the LUMO+1.
Plots of the resonant wave function for a photoelectron of e symmetry for ionization from the HOMO of 2-butyne that occurs in the model calculations at a photon energy of 10.2 eV and with a width of 1.9 eV.
Vibrational Frequencies for the 2-Butyne Ground State Neutral and Ion.
Observed vibrational frequencies for the 2-butyne Ion.
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