Effect of cluster environment on the electron attachment to 2-nitrophenol

Effect of cluster environment on the electron attachment to 2-nitrophenol (2NP) is studied in homogeneous 2NP clusters and heterogeneous clusters of 2NP, argon and water. The cluster environment significantly reduces fragmentation of 2NP after electron attachment. Parent cluster anions 2NP(n)(-) are primary reaction products in both, homogeneous and heterogeneous clusters. Non-dissociative electron attachment to homogeneous clusters proceeds at low energies <2 eV, presumably via dipole-supported states. In heterogeneous clusters, the interaction with low energy (<2 eV) electrons is shielded by the solvent. Surprisingly, the energetic threshold for the electron attachment rises with the number (n) of 2NP molecules in the cluster (2NP)(n)(-). This rise can be either due to a strong change of the 2NP conformation induced by the cluster environment or due to the the competition with electron autodetachment after proton transfer that has been first observed by Allan in the formic acid dimer [M. Allan, Phys. Rev. Lett. 98, 123201 (2007)]. We observe the same threshold rise for complex Ar-m center dot(2NP)(n)(-) and H2O center dot(2NP)(n)(-) anions. This indicates that the electron attachment to 2-nitrophenol in cluster environment is more influenced by the solute - solute interaction compared to the solute - solvent interaction.