Dissociation-ionization and ionization-dissociation by multiphoton absorption of acetaldehyde at 266 and 355 nm: dissociation pathways

The experimental results from the interaction of a sample of acetaldehyde (CH3 CHO) with laser radiation at intensities between 10(9) and 10(11) Wcm(-2) and wavelengths of 266 and 355 nm are reported. As a result of multiple photon absorption, cations from ionization-dissociation (I-D) or dissociation-ionization (D-I) processes, were detected using a reflectron time of flight mass spectrometer. The processes I-D is predominant at 355 nm and D-I is predominant at 266 nm. The formation of different ions is discussed. From analysis of the ratios between the ion currents [I(CH3CO+)+I(CO+)]/[I(CH3+)+I(HCO+)], originated from the C-C bond or from the C-H bond breaking at different laser intensities, the predominant channels are determined.