Influence of the N atom and its position on electron photodetachment of deprotonated indole and azaindole
Jennifer A. Noble, Ernesto Marceca, Claude Dedonder, Christophe Jouvet
Abstract
Electron photodetachment of cold deprotonated indole and azaindole anions has been studied by use of a mass-selective photofragmentation spectrometer capable of negative ion and neutral particle detection. The electron affinities of the indolyl radical and the 5-, 6- and 7-azaindolyl radicals have been measured with an uncertainty of less than 0.002 eV. The presence of the nitrogen atom in the six-membered ring of the azaindolide anions stabilises the electron by 0.3 to 0.4 eV, i.e. about 10-15%, compared to the indolide anion. No fragmentation was observed in either the anionic or radical forms of the species studied. The appearance of dipole-bound states in the spectra of deprotonated 6- and 7-azaindole anions allowed us to analyse the vibrational structure of the neutral 6- and 7-azaindolyl radicals produced following photodetachment. Although no dipole-bound states were clearly identified for deprotonated indole or 5-azaindole, the shape of the photodetachment threshold suggests the presence of a very weakly dipole-bound state or dipole resonance, which cannot be resolved with our laser resolution.