Electron attachment to formamide clusters in helium nanodroplets.

Electron attachment to formamide clusters in helium nanodroplets is reported for the first time. In contrast to the gas phase, parent anions are seen following low energy electron attachment to both the monomer and the small clusters. This is attributed to formation of dipole (or quadrupole) bound anions. In addition to the bare anions, the mass spectra also show the monomer and clusters with attached helium atoms. The affinity for attaching helium atoms strongly varies with cluster size; for example, the dimer anion is more than 10 times more likely to bind one or more helium atoms than the monomer. Possible binding sites for the helium atoms are discussed.