We report unambiguous experimental and theoretical evidence of intramolecular photoelectron diffraction in the collective vibrational excitation that accompanies high-energy photoionization of gas-phase CF4, B-F 3, and CH4 from the 1s orbital of the central atom. We show that the ratios between vibrationally resolved photoionization cross sections (v-ratios) exhibit pronounced oscillations as a function of photon energy, which is the fingerprint of electron diffraction by the surrounding atomic centers. This interpretation is supported by the excellent agreement between first-principles static-exchange and time-dependent density functional theory calculations and high resolution measurements, as well as by qualitative agreement at high energies with a model in which atomic displacements are treated to first order of perturbation theory. The latter model allows us to rationalize the results for all the v-ratios in terms of a generalized v-ratio, which contains information on the structure of the above three molecules and the corresponding molecular cations. A fit of the measured v-ratios to a simple formula based on this model suggests that the method could be used to obtain structural information of both neutral and ionic molecular species. (C) 2013 AIP Publishing LLC.
Intramolecular photoelectron diffraction in the gas phase
Decleva P;
2013
Abstract
We report unambiguous experimental and theoretical evidence of intramolecular photoelectron diffraction in the collective vibrational excitation that accompanies high-energy photoionization of gas-phase CF4, B-F 3, and CH4 from the 1s orbital of the central atom. We show that the ratios between vibrationally resolved photoionization cross sections (v-ratios) exhibit pronounced oscillations as a function of photon energy, which is the fingerprint of electron diffraction by the surrounding atomic centers. This interpretation is supported by the excellent agreement between first-principles static-exchange and time-dependent density functional theory calculations and high resolution measurements, as well as by qualitative agreement at high energies with a model in which atomic displacements are treated to first order of perturbation theory. The latter model allows us to rationalize the results for all the v-ratios in terms of a generalized v-ratio, which contains information on the structure of the above three molecules and the corresponding molecular cations. A fit of the measured v-ratios to a simple formula based on this model suggests that the method could be used to obtain structural information of both neutral and ionic molecular species. (C) 2013 AIP Publishing LLC.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.