Dissociative electron attachment to HCCCN

Dissociative electron attachment to cyanoacetylene (propiolonitrile) HCCCN has been observed in the electron energy range 0–12 eV. Negative ions are formed in two main bands with maxima at ∼1.6 eV (CCCN − ) and ∼5.3 eV (CCCN − , CN − , HCC − and CC − ). There are also weaker resonances which lead to dissociative electron attachment to form CN − , HCC − and CC − with a maximum intensity at ∼8.1 eV and CCCN − , CN − and CC − at ∼11.2 eV. A trace of CCN − is observed at ∼9.1 eV. The positions of the main dissociative attachment bands observed are close to positions of π* resonances recently calculated by Sommerfeld and Knecht. Calculations have also been performed in this work, which confirm the position of the π* orbitals. The electron affinity of the CCCN radical is determined as 4.59±0.25 eV from the threshold for CCCN − formation at 1.32±0.15 eV. Dissociative electron attachment to this molecule will act as a source of negative ions in extraterrestrial environments where electrons are present with more than 1.3 eV energy.