Photoelectron spectroscopy of acetone cluster anions,

Photoelectron images of [ ( CH 3 ) 2 CO ] n - ( n = 2 , 5 – 15 ) were recorded at 3.49 eV. Analysis of the images provided the vertical detachment energies (VDEs) and photoelectron angular distributions (PADs) of [ ( CH 3 ) 2 CO ] n - . The n-dependence of these quantities starts with VDE = 0.83 ± 0.03 eV and β ≈ −0.3 at n = 2, and it ends up with 2.83 ± 0.03 eV and ≈0.1 at n = 15. These findings, in conjunction with ab initio results, indicate: (1) the formation of a specific anion structure at n = 2; and (2) the presence of a solvent-stabilized (CH3)2CO− valence anion in the larger analogues.