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.

We have investigated the effect of microsolvation on the low-lying pure shape π resonances of thymine. Static-exchange R-matrix calculations for elastic electron scattering from microhydated thymine, i.e., Thy-(HO) with n = 1,2,3,5 are discussed. We look at the additive effect of water molecules hydrogen-bonding to thymine. The results for Thy-(HO) show that both π resonances appear at lower energy in the cluster than in isolated thymine, but that the energy shift is different for each resonance. We discuss how our results could help explain the quenching of hydrogen loss in dissociative electron attachment of microhydrated thymine recently recorded experimentally.

We present R-matrix calculations for electron scattering from microhydrated pyridine. We studied the pyridine-HO cluster at static-exchange (SE), SE + polarization, and close-coupling levels, and pyridine-(HO) n = 2, 3, and 5 at SE level only in order to investigate the effect of hydrogen bonding on the resonances of pyridine. We analyse the results in terms of direct and indirect effects. We observe that the total (direct plus indirect) effect of microhydration leads to the stabilization of all resonances studied, both shape and core-excited. The size of the shift is different for different resonances and seems to be linked to the dipole moment of the cluster.

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