W. Trott, N. Blais, E. A. Walters
Oct 1, 1978
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Journal of Chemical Physics
Abstract
High resolution photoionization efficiency curves have been obtained for CH3COCH3+ and CD3COCD3+ using supersonic molecular beam sampling. As a result of adiabatic cooling during the nozzle expansion, sufficient concentrations of (CH3COCH3)2, (CD3COCD3)2, (CH3COCH3)3, and (CH3COCH3)4 were formed to permit the study of their photoion yield curves as well. Appearance potential curves have been determined for CH3CO+, CD3CO+, and (CH3COCH3) ⋅CH3CO+ fragments. The measured ionization potentials of acetone and acetone‐d6 monomers are 9.694±0.006 and 9.695±0.006 eV, respectively. Transitions to higher vibrational levels in CH3COCH3+ are seen at 320, 695, and 930−1370 cm−1 above threshold. The effect of perdeutero substitution is to reduce these frequencies to 260 and 660–1100 cm−1. Appearance potentials of CH3CO+ and CD3CO+ fragments are observed at 10.52±0.02 and 10.56±0.02 eV, respectively. The measured ionization energies for (CH3COCH3)n, n=1–4, are found to decrease linearly as a function of 1/n. Observed io...