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©2021 American Physical Society. The authors would like to acknowledge R. Tranter for his ongoing technical support of the experimental apparatus used in these experiments. Funding is acknowledged from the Australian Research Council Discovery program (Grant No. DP190100696). V.G. acknowledges support from the EPSRC Doctoral Training Partnership EP/T518165/1. F.B. and G.G. acknowledge partial financial support from the Spanish Ministerio de Ciencia e Innovacion (Project No. PID2019-104727RB-C21) and CSIC (Project No. LINKA20085)., The present paper provides a joint experimental and theoretical study of positron scattering from pyrazine. Experimental data were measured employing a low-energy positron beamline, and covered an energy range from 1 to 79 eV. Cross sections were measured for total scattering, total elastic scattering, positronium formation, direct ionization, and the sum of the total discrete electronic-state excitation processes. In addition, measured total electronic excitation cross sections for the individual 1(1)B3u, 1(1)B2u, 1(1)B1u, and 2(1)B2u states are also reported. Finally, experimental elastic differential cross sections (DCSs), here in the energy range 1-20 eV, are also presented. Results from two theoretical approaches are given: the R-matrix approach and the independent atom method with screening corrected additivity rule and interference terms. Where a comparison between our experimental and theoretical results could be made, the level of accord varied from being quite good to marginal depending on the actual scattering process under consideration. Last, a comparison between the present elastic DCS results and those from our earlier study on positron scattering from pyrimidine [Palihawadana et al., Phys. Rev. A 88, 012717 (2013)] showed a somewhat unexpected level of agreement., Ministerio de Ciencia e Innovación (MICINN), Consejo Superior de Investigaciones Científicas (CSIC), Australian Research Council, EPSRC Doctoral Training Partnership UK, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

We have calculated cross sections for elastic and inelastic electron scattering from pyridine in the energy range 1 eV to 1 keV. The R-matrix and IAM-SCAR methods have been used for low and higher collision energies, respectively. Agreement with available theoretical data is good. We have also examined the formation of shape resonances and compared our results with existing experimental data. We compare the results with data for electron scattering from pyrimidine. 2014 American Chemical Society.

We present and discuss recent results, both experimental and theoretical (where possible), for electron impact excitation of the 3s[32]1 and 3s′[12]1 electronic states in neon, elastic electron scattering from the structurally similar molecules benzene

Total electron scattering cross sections for pyrazine in the energy range 10-500 eV have been measured with a new magnetically confined electron transmission-beam apparatus. Theoretical differential and integral elastic, as well as integral inelastic, cross sections have been calculated by means of a screening-corrected form of the independent-atom representation (IAM-SCAR) from 10 to 1000 eV incident electron energies. The present experimental and theoretical total cross sections show a good level of agreement, to within 10%, in the overlapping energy range. Consistency of these results with previous calculations (i.e., the R-matrix and Schwinger Multichannel methods) and elastic scattering measurements at lower energies, below 10 eV, is also discussed.

We report a computational investigation of positron scattering by pyrimidine (C4H4N2) in the gas phase. Integral and differential cross sections have been calculated over a broad energy range by employing two distinct ab initio quantum scattering methods: the R-matrix method and a corrected form of the independent-atom representation, at low and high energies, respectively. Since pyrimidine is a strong polar molecule further dipole-induced excitations have been calculated in the framework of the first Born approximation. Good agreement is found between the different computational models and fair agreement is found with prior experimental results.

We present results of measurements and calculations of elastic electron scattering from 1,4-dioxane in the energy range of 0-1000 eV. Absolute differential and integral elastic cross sections have been measured using a crossed electron-molecule beam spectrometer and the relative flow technique, at four energies in the 10-30 eV range and for scattered electrons in the angular range 20°-129°. The measured cross sections are compared with results from R-matrix computations, at the static exchange plus polarization level, calculated at energies between 0-20 eV, and with calculations employing the independent atom model with the screening corrected additivity rule (IAM-SCAR). Those latter computations were conducted at energies between 1 and 1000 eV. Agreement between the measured and R-matrix cross sections was typically found to be good at all common energies, whereas agreement with IAM-SCAR was satisfactory only at 30 eV. To the best of our knowledge, the present results are the first absolute data to be published in the literature for this scattering system.

Low-energy dissociative electron attachment (DEA) to the CF2Cl2 and CF3Cl molecules in a water cluster environment is investigated theoretically. Calculations are performed for the water trimer and water hexamer. It is shown that the DEA cross section is strongly enhanced when the attaching molecule is embedded in a water cluster, and that this cross section grows as the number of water molecules in the cluster increases. This growth is explained by a trapping effect that is due to multiple scattering by water molecules while the electron is trapped in the cluster environment. The trapping increases the resonance lifetime and the negative ion survival probability. This confirms qualitatively existing experiments on electron attachment to the CF2Cl2 molecule placed on the surface of H2O ice. The DEA cross sections are shown to be very sensitive to the position of the attaching molecule within the cluster and the orientation of the electron beam relative to the cluster.