title: The triplet states of butadiene and benzene by He+ impact authors: Kenichi Iwamoto and Akira Matsumoto affiliations: Materials Science, College of Integrated Arts and Sciences, Osaka Prefecture University, Japan summary: The excited electronic states of trans-1,3-butadiene and benzene by He+ impact were measured with the ion energy loss spectrometer equipped with the Matsuda plate. Two triplet states of butadiene were observed. The spectrum of benzene was obtained by separating of the first and second triplet states. These excitation energies were in good agreement with the results of the electron-energy loss experiments.