Energy dependences of fragment ion yields from acetone photoexcited in the C1s and O1s transition regions

Abstract

Fragment ions from acetone were measured in the regions of the C1s and O1s electron transitions using monochromatized synchrotron radiation and a time-of-flight mass spectrometer. Partial yield spectra for the fragment ions were observed in these inner-shell regions. Atomic hydrogen ion shows the highest yield and CH + 3 shows the second highest for all the energies studied. Although a dramatic effect on site-specific decomposition was not found, the C1s excitation to Rydberg orbitals induced a stronger decomposition than the π* orbital excitation; e.g. relative intensities of C m H + ( m=1–3) become higher at the Rydberg excitation than those of C m H + 2 and C m H + 3. The C1s ionization provided a heavier C–C bond rupture than the π* and Rydberg orbital excitation. Near the OK-edge, C 3H + 3 exhibits a high yield only at the π* resonance, and the relative yield of CH + 3 becomes considerably higher above the ionization threshold than at the π* resonance.