Dissociative Photoionization of the CH Isomers Cycloheptatriene and Toluene: Looking at Two Sides of the Same Coin Simultaneously.

The dissociation of energy-selected 1,3,5-cycloheptatriene (CHT) and toluene (Tol) cations was investigated by imaging photoelectron photoion coincidence spectroscopy. In the measured energy ranges of 10.30-11.

Thermochemistry of the smallest QOOH radical from the roaming fragmentation of energy selected methyl hydroperoxide ions.

The dissociative photoionization processes of methyl hydroperoxide (CH3OOH) have been studied by imaging Photoelectron Photoion Coincidence (iPEPICO) spectroscopy experiments as well as quantum-chemical and statistical rate calculations. Energy selected CH3OOH+ ions dissociate into CH2OOH+, HCO+, CH3+, and H3O+ ions in the 11.4-14.

Radical Thermometers, Thermochemistry, and Photoelectron Spectra: A Photoelectron Photoion Coincidence Spectroscopy Study of the Methyl Peroxy Radical.

We investigated the simplest alkylperoxy radical, CHOO, formed by reacting photolytically generated CH radicals with O, using the new combustion reactions followed by photoelectron photoion coincidence (CRF-PEPICO) apparatus at the Swiss Light Source. Modeling the experimental photoion mass-selected threshold photoelectron spectrum using Franck-Condon simulations including transitions to triplet and singlet cationic states yielded the adiabatic ionization energy of 10.265 ± 0.

CRF-PEPICO: Double velocity map imaging photoelectron photoion coincidence spectroscopy for reaction kinetics studies.

Photoelectron photoion coincidence (PEPICO) spectroscopy could become a powerful tool for the time-resolved study of multi-channel gas phase chemical reactions. Toward this goal, we have designed and tested electron and ion optics that form the core of a new PEPICO spectrometer, utilizing simultaneous velocity map imaging for both cations and electrons, while also achieving good cation mass resolution through space focusing. These optics are combined with a side-sampled, slow-flow chemical reactor for photolytic initiation of gas-phase chemical reactions.

Bifurcated dissociative photoionization mechanism of acetic acid anhydride revealed by imaging photoelectron photoion coincidence spectroscopy.

The fragmentation processes of internal energy selected acetic acid anhydride cations, AcO, were investigated by imaging photoelectron photoion coincidence (iPEPICO) spectroscopy. The first dissociation channel leads to the formation of CHC(O)OCO (m/z = 87) by a CH-loss. The 0 K appearance energy (E) was determined to be 10.