Photoelectron diffraction in methane probed via vibrationally resolved inner-valence photoionization cross-section ratios. Issue 4 (8th January 2016)

• Record Type: Journal Article
• Authors: Nandi, Saikat; Plésiat, Etienne; Patanen, Minna; Miron, Catalin; Bozek, John D.; Martín, Fernando; Toffoli, Daniele; Decleva, Piero
• Is Part Of: Physical chemistry chemical physics. Volume 18:Issue 4(2016)
• Page Start: 3214
• Page End: 3222
• Publication Date: 2016-01-08
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c5cp07017a
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Interplay between interference and diffraction effects inside molecular potential has been observed in the vibrationally resolved photoionization studies of the 2a1 orbital in CH4 . Abstract : Vibrationally resolved photoionization of the 2a1 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 2a1 −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 1a1 −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.