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We report results from a joint theoretical and experimental investigation into electron scattering from the important organic species phenol (C6H5OH). Specifically, differential cross sections (DCSs) have been measured and calculated for the electron-impact excitation of the electronic states of C6H5OH. The measurements were carried out at energies in the range 15-40 eV, and for scattered-electron angles between 10° and 90°. The energy resolution of those experiments was typically ~80 meV. Corresponding Schwinger multichannel method with pseudo-potentials calculations, with and without Born-closure, were also performed for a sub-set of the excited electronic-states that were accessed in the measurements. Those calculations were conducted at the static exchange plus polarisation (SEP)-level using a minimum orbital basis for single configuration interaction (MOBSCI) approach. Agreement between the measured and calculated DCSs was typically fair, although to obtain quantitative accord, the theory would need to incorporate even more channels into the MOBSCI. [ABSTRACT FROM AUTHOR]

We present experimental electron-energy loss spectra (EELS) that were measured at impact energies of 20 and 30 eV and at angles of 90° and 10°, respectively, with energy resolution ~70 meV. EELS for 250 eV incident electron energy over a range of angles between 3° and 50° have also been measured at a moderate energy resolution (~0.9 eV). The latter spectra were used to derive differential cross sections and generalised oscillator strengths (GOS) for the dipole-allowed electronic transitions, through normalization to data for elastic electron scattering from benzene. Theoretical calculations were performed using time-dependent density functional theory and single-excitation configuration interaction methods. These calculations were used to assign the experimentally measured spectra. Calculated optical oscillator strengths were also compared to those derived from the GOS data. This provides the first investigation of all singlet and triplet excited electronic states of phenol up to the first ionization potential. [ABSTRACT FROM AUTHOR]

We report on the shape resonance spectra of uracil, 5-fluorouracil, and 5-chlorouracil, as obtained from fixed-nuclei elastic scattering calculations performed with the Schwinger multichannel method with pseudopotentials. Our results are in good agreement with the available electron transmission spectroscopy data, and support the existence of three p* resonances in uracil and 5-fluorouracil. As expected, the anion states are more stable in the substituted molecules than in uracil. Since the stabilization is stronger in 5-chlorouracil, the lowest p* resonance in this system becomes a bound anion state. The present results also support the existence of a low-lying s*CCl shape resonance in 5-chlorouracil. Exploratory calculations performed at selected C-Cl bond lengths suggest that the s*CCl resonance could couple to the two lowest p* states, giving rise to a very rich dissociation dynamics. These facts would be compatible with the complex branching of the dissociative electron attachment cross sections, even though we cannot discuss any details of the vibration dynamics based only on the present fixed-nuclei results. [ABSTRACT FROM AUTHOR]

Trifluoroiodomethane (CF 3 I) is one of the most appealing candidates for applications in plasma-based technologies in view of its many interesting advantages when compared to more standard gases such as trifluorobromomethane (CF 3 Br). Low-energy electrons are prone to decomposing these molecules into reactive species, and knowledge on the collision cross sections is fundamental for modeling transport and reactivity in plasma environments. Despite many studies on electron collisions with the abovementioned molecules, there are conflicting results on the assignment of shape resonances and on the magnitudes of total cross sections. Here, we try to clarify these aspects by performing ab initio electron scattering calculations. We found integral cross sections in fair agreement with the most recent measurements, in contrast to previous reports. For each molecule, we found a σ CX * resonance (antibonding between the carbon and the heavy halogen) at 1 eV in CF 3 Br and at ∼0 eV in CF 3 I. Furthermore, there are three shape resonances of σ CF * character; two are degenerate and account for a broad feature around 6 eV and the other one appears around 9.5 eV. We also discuss the possible role of the degenerate resonance in dissociative electron attachment reactions, as well as the impact of the heavy halogen on the cross sections and on the shape resonances.