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-(H2O)n 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-(H2O)5 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.

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Schwinger multichannel method calculations for smaller targets26,38 show that there can be differences of up to 0.6 eV in the shifts calculated with the SE and SEP approximations. In our calculations for Pyr-H2O (see Paper I25), the SEP approximation produced a shift 20% bigger for the first resonance but similar in size for the second.

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