Electron impact excitation of the singlet and triplet B1u π → π∗ states of ethylene near threshold

The electron impact excitation functions of the 1 3B1u and 1 1B1u π → π∗ states of ethylene are measured. The triplet excitation function has a broad peak near 6.5 eV that is attributed to the π−1(π∗)2 anion state, and the singlet excitation function displays sharp structure near threshold due to the π−1(3s)2 anion state.