Low-energy electron impact study of acetone

A low-energy, high resolution, electron impact spectrometer with a molecular beam target has been constructed and used to study the electronic energy levels of acetone vapor. Similar spectra were also taken with a second electron spectrometer having a static gas target. Both sets of spectra are essentially identical and show the expected singlet states at 4.37, 6.35, and 7.45 eV, the first triplet state at 4.16 eV, and a very broad second triplet process from 5.3 to 6.1 eV with an intensity maximum at 5.88 eV. Attempts to resolve vibrational structure in the latter band were unsuccessful, even though vibrational spacings of 0.14 eV were easily resolved elsewhere in the spectrum.