We present in this study a self-consistent set of scattering cross sections for positron collisions with water molecules, in the energy range 0.1–10 000 eV, with the prime motivation being to provide data for modelling purposes. The structure of the database is based on a new model potential calculation, including interference terms, which provides differential and integral elastic as well as integral inelastic positron scattering cross sections for water molecules over the whole energy range considered here. Experimental and theoretical data available in the literature have been integrated into the database after a careful analysis of their uncertainties and their self-consistency. These data have been used as input parameters for a step-by-step Monte Carlo simulation procedure, providing valuable information on energy deposition, positron range, and the relative percentages of specific interactions (e.g. positronium formation, direct ionisation, electronic, vibrational and rotational excitations) in gaseous and liquid water.

We report integral cross sections for electron interactions with tungsten and beryllium atoms in the incident electron energy range from 0.1 up to 5000 eV. The calculated cross sections are obtained for electron–atom scattering processes represented by a complex potential. For tungsten, ionization cross sections are discussed in the electron energy region from threshold up to 5000 eV against the available data from the Deutsch–Märk formalism and a semi-empirical complex scattering potential. Although a reasonable agreement for the ionization cross sections has been found in the overlapping energy region, inconsistencies on the integral inelastic cross sections from the previous semi-empirical approach based on a complex scattering potential ionization contribution, are now amended and comprehensively explained. For beryllium atoms an excellent agreement with previous ‘state-of-the-art’ scattering theory calculations has been found for the integral elastic cross sections. However, the partial contribution of the excitation and ionization channels to the inelastic part shows serious discrepancies which deserve further investigations. Calculated elastic differential cross sections for tungsten are also reported from 0.1 to 5000 eV for scattering angles from 0° to 180°. The present set of cross sectional data may be of relevance for the plasma fusion community.

Total electron scattering cross sections, from para-benzoquinone, for impact energies ranging between 1 to 200 eV, have been obtained by measuring the attenuation of a linear electron beam under magnetic confinement conditions. Random uncertainty limits on these values have been found to be within 5%. Systematic errors, due to the axial magnetic beam conditions in combination with the acceptance angle of the detector, have been evaluated by integrating our calculated independent atom model with the screening corrected additivity rule and interference term elastic differential cross sections over that detection acceptance angle. Our previous calculations and measurements on this molecule (Jones et al., J. Chem. Phys., 2018, 148, 124312 and J. Chem. Phys., 2018, 148, 204305), have been compiled and complemented with new elastic and inelastic scattering cross section calculations in order to obtain a comprehensive cross section data base, within the considered energy range, for modelling purposes. The self-consistency of the present data set has been evaluated by simulating the electron transport of 15 eV electrons in para-benzoquinone, and comparing those results with the observed transmitted intensity distribution.

A novel experimental setup has been implemented to provide accurate electron scattering cross sections from molecules at low and intermediate impact energies (1-300 eV) by measuring the attenuation of a magnetically confined linear electron beam from a molecular target. High-resolution electron energy is achieved through confinement in a magnetic gas trap where electrons are cooled by successive collisions with N₂. Additionally, we developed and present a method to correct systematic errors arising from energy and angular resolution limitations. The accuracy of the entire measurement procedure is validated by comparing the N₂ total scattering cross section in the considered energy range with benchmark values available in the literature.

We present a comprehensive revisited experimental high-resolution vacuum ultraviolet (VUV) photoabsorption spectrum of ammonia, NH₃, covering for the first time the full 5.4–10.8 eV energy-range, with absolute cross sections determined. The calculations on the vertical excitation energies and oscillator strengths were performed using the equation-of-motion coupled cluster method restricted to single and double excitation levels and used to help reanalyze the observed Rydberg structures in the photoabsorption spectrum. The VUV spectrum reveals several new features that are not previously reported in the literature, with particular reference to the vibrational progressions of the (${\tilde{D}}^1{E}^{\prime }\leftarrow {\tilde{X}}^1{A}_1^{\prime }$ ), the (${\tilde{F}}^1{E}^{\prime }\leftarrow {\tilde{X}}^1{A}_1^{\prime }$ ), and the (${\tilde{G}}^1{A}_2^{″}\leftarrow {\tilde{X}}^1{A}_1^{\prime }$ ) absorption bands. In addition, new Rydberg members have been identified in $\left(nd{a}_1^{\prime }\leftarrow 1a_2^{″}\right)\left({\tilde{D}}^{\prime \prime 1}{A}_2^{″}\leftarrow {\tilde{X}}^1{A}_1^{\prime }\right)$ , where n > 3 has not been reported before as well as in $\left(nd{e}^{″}\leftarrow 1a_2^{″}\right)\left({\tilde{F}}^1{E}^{\prime }\leftarrow {\tilde{X}}^1{A}_1^{\prime }\right)$ and in $\left(ns{a}_1^{\prime }\leftarrow 1a_2^{″}\right)\left({\tilde{G}}^1{A}_2^{″}\leftarrow {\tilde{X}}^1{A}_1^{\prime }\right)$ . The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of ammonia in the Earth’s atmosphere (0–50 km).