Theoretical study of resonance formation in microhydrated molecules. I. Pyridine-(H2O)n, n = 1,2,3,5

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-(H 2 O)π with π = 1,2,3,5 are discussed. We look at the additive effect of water molecules hydrogen-bonding to thymine. The results for Thy-(H 2 O) 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.