Low energy electron impact in gas phase glycine, alanine and propanoic acid: Electronic, vibrational excitations and negative ions

Excitation of electronic states below 10 eV and resonant vibrational excitation around 2 eV are investigated in gas phase glycine and d-alanine by electron energy loss spectroscopy. Location of singlet states observed between 5 eV and 10 eV is in good agreement with recent calculations. Vibrational excitation concerns mainly the COOH group and CH stretch modes. Structures in (M–H)− cross-sections between 1 eV and 2 eV have been revisited. Dips are clearly observed revealing OH stretch excitation, interpreted as cusps due to competition between decay channels of the resonant state. (M–H)− anions and vibrational excitation have also been investigated in propanoic acid for comparison.