Vibrationally specific photoionization cross sections of acrolein leading to the $\tilde{X}\,{}^2\!A^{\prime }$X̃A′2 ionic state

Abstract

The vibrational branching ratios in the photoionization of acrolein for ionization leading to the X̃²A' ion state were studied. Computed logarithmic derivatives of the cross section and the corresponding experimental data derived from measured vibrational branching ratios for several normal modes (ν9, ν10, ν11, and ν12) were found to be in relatively good agreement, particularly for the lower half of the 11-100 eV photon energy range considered. Two shape resonances have been found near photon energies of 15.5 and 23 eV in the photoionization cross section and have been demonstrated to originate from the partial cross section of the A' scattering symmetry. The wave functions computed at the resonance complex energies are delocalized over the whole molecule. By looking at the dependence of the cross section on the different normal mode displacements together with the wave function at the resonant energy, a qualitative explanation is given for the change of the cross sections with respect to changing geometry.

Extreme Low-Temperature Combustion Chemistry: Ozone-Initiated Oxidation of Methyl Hexanoate

“…Calculated total rate constants for O + DME and O + four methyl esters (MHX = methyl hexanoate, MPE = methyl pentanoate, MB = methyl butanoate, MPR = methyl propanoate). The present results (solid lines) are compared with the 1DHR calculations (dashed lines) for DME (present work) and MPR (taken from ref ) and with an experimentally derived Arrhenius expression (●) for DME.…”

“…For larger species with unknown photoionization cross sections, every effort was made to remove all experimental factors, as discussed in detail in refs and . Although photoionization cross sections can be calculated theoretically, ,− it has been demonstrated that the uncertainty is substantial for large molecules, resulting in the data being less useful for future model comparisons and validation. Instead, we present these data in the Supporting Information as mole fraction x cross section as seen in Figure for the ketohydroperoxide (C 7 H 15 O 5 ).…”