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EnglishVibrationally resolved photoionization of the 2a(1) orbital in methane has been studied both experimentally and theoretically, over a wide range of photon energies (40-475 eV). A vibrational progression associated with the symmetric stretch mode of the 2a(1)(-1) single-hole state was observed in the experimental photoelectron spectra. Individual vibrational sub-states of the spectra were found to be best modeled by asymmetric line-shapes with linewidths gradually increasing with the vibrational quantum number. This indicates the occurrence of a pre-dissociation process for the involved ionic state, discussed here in detail. Finally, diffraction patterns were observed in the vibrational branching ratios for the first three vibrational sub-states ("v-ratios") of the experimental photoelectron spectra. They are found to be in excellent qualitative agreement with those obtained from ab initio models. Compared with previous studies of the 1a(1)(-1) core-shell photoionization of methane, the period of oscillation of the v-ratios is found to be very different and the phases are of opposite signs. This suggests a strong interplay between the electron diffraction and interference effects inside the molecular potential.
| Titolo: | Photoelectron diffraction in methane probed via vibrationally resolved inner-valence photoionization cross-section ratios |
| Autori: | |
| Data di pubblicazione: | 2016 |
| Rivista: | |
| Abstract: | Vibrationally resolved photoionization of the 2a(1) orbital in methane has been studied both experimentally and theoretically, over a wide range of photon energies (40-475 eV). A vibrational progression associated with the symmetric stretch mode of the 2a(1)(-1) single-hole state was observed in the experimental photoelectron spectra. Individual vibrational sub-states of the spectra were found to be best modeled by asymmetric line-shapes with linewidths gradually increasing with the vibrational quantum number. This indicates the occurrence of a pre-dissociation process for the involved ionic state, discussed here in detail. Finally, diffraction patterns were observed in the vibrational branching ratios for the first three vibrational sub-states ("v-ratios") of the experimental photoelectron spectra. They are found to be in excellent qualitative agreement with those obtained from ab initio models. Compared with previous studies of the 1a(1)(-1) core-shell photoionization of methane, the period of oscillation of the v-ratios is found to be very different and the phases are of opposite signs. This suggests a strong interplay between the electron diffraction and interference effects inside the molecular potential. |
| Handle: | http://hdl.handle.net/11368/2870478 |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1039/C5CP07017A |
| Appare nelle tipologie: | 1.1 Articolo in Rivista |
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http://hdl.handle.net/11368/2870478
