Threshold Photoelectron Spectroscopy, Dissociative Photoionization, and Pyrolysis of Aziridine

High Resolution Image Download MS PowerPoint Slide The threshold photoelectron spectrum, dissociative photoionization, and pyrolysis of aziridine, a nitrogen-bearing hydrocarbon of c-C 2 H 4 NH composition, were studied by double-imaging photoelectron photoion coincidence spectroscopy at the Swiss Light Source. The aziridine adiabatic ionization energy (AIE) was measured at (9.30 ± 0.03) eV. The full ground-state band of the threshold photoelectron spectrum, exhibiting strong anharmonicity, was simulated using the Thawed Gaussian Approximation (TGA) method. At higher photon energies, dissociative photoionization products corresponding to hydrogen loss and methyl loss were identified with respective appearance energies of (10.59 ± 0.05) eV and (10.53 ± 0.05) eV obtained by fitting a statistical model to the dissociative ionization data. Aziridine pyrolysis was also studied at a temperature of 1360 K. Isomerization plays an important role with multiple C 2 H 5 N isomers contributing to the thermal decomposition of neutral aziridine. Ethenamine, methyl radical, and radicals of H 2 CN • composition were detected as pyrolysis products. The AIE for ethenamine was measured at (8.16 ± 0.03) eV. Isomerization to ( E / Z )-ethanimine and N -methylmethanimine was also implicated in the pyrolysis data.