The electronic state spectroscopy of acetone (CH₃)₂CO has been investigated using high-resolution VUV photoabsorption spectroscopy in the energy range 3.7–10.8 eV. New vibronic structure has been observed, notably in the low energy absorption band assigned to the 1¹A₁ → 1¹A₂ (n_y → π*) transition. The local absorption maximum at 7.85 eV has been tentatively attributed to the 4¹A₁ (π → π*) transition. Six Rydberg series converging to the lowest ionisation energy (9.708 eV) have been assigned as well as a newly-resolved ns Rydberg series converging to the first ionic excited state (12.590 eV). Rydberg orbitals of each series have been classified according to the magnitude of the quantum defect (δ) and are extended to higher quantum numbers than in the previous analyses.

The interaction of low‐energy electrons with biomolecules plays an important role in the radiation‐induced alteration of biological tissue at the molecular level. At electron energies below 15 eV, dissociative electron attachment is one of the most important processes in terms of the chemical transformation of molecules. So far, a common approach to study processes at the molecular level has been to carry out investigations with single biomolecular building blocks like pyrimidine as model molecules. Electron attachment to single pyrimidine, as well as to pure clusters and hydrated clusters, was investigated in this study. In striking contrast to the situation with isolated molecules and hydrated clusters, where no anionic monomer is detectable, we were able to observe the molecular anion for the pure clusters. Furthermore, there is evidence that solvation effectively prevents the ring fragmentation of pyrimidine after electron capture.

The electronic state spectroscopy of pyrimidine C₄H₄N₂ has been investigated using both high resolution VUV photoabsorption in the energy range 3.7 to 10.8 eV (335 to 115 nm) and lower resolution electron energy loss in the range 2 to 15 eV. The low energy absorption band, assigned to the (π*) ← 7b₂(n_N) (1¹B₁ ← 1¹A₁) transition, at 3.85(4) eV and the vibrational progressions superimposed upon it have been observed for the first time, due to the availability of a high-resolution photon beam (0.075 nm), corresponding to 3 meV at the midpoint of the energy range studied. Vibronic coupling has been shown to play an important role dictating the nature of the observed excited states, especially for the lowest ¹B₁ state. The 2¹B₁ state is proposed to have its origin at 7.026 eV according to the vibrational excitation reported in this energy region (7.8–8.4 eV). New experimental evidence of 4¹A₁ state with a maximum cross section at 8.800 eV is supported by previous ab initio quantum chemical calculations. Rydberg series have been assigned converging to the three lowest ionisation energy limits, 9.32 eV (²B₂), 10.41 eV (²B₁) and 11.1 eV (²A₁ + ²A₂) with new members reported for the first time and classified according to the magnitude of the quantum defects (δ). Additionally, the absolute differential cross section for inelastic electron scattering has been measured for the most intense band from 6.9 to 7.8 eV assigned to ¹ππ* (3¹A₁ + 2¹B₂).