Anionic oligomerization of acrylonitrile molecules initiated by intracluster electron transfer from alkali metal atoms: Photoionization mass spectrometry of M(CH2=CHCN)(n) (M = Li, Na, and K)

We investigated the photoionization mass spectrometry of clusters of alkali metal atoms (M = Li, Na and K) solvated with acrylonitrile (AN; CH2=CHCN) molecules to obtain the information on size-dependent stability of the clus ters. In the photoionization mass spectra of M-m(AN)(n), strong ion signals were observed at M+(AN)(3). The M+(AN)(n) (n = 6 and 9) ions were also cle arly observed as magic numbers in the mass spectra of M = Na and K. By comp arison with the mass spectrum of cluster ions formed by ion-molecule reacti ons in the cluster source, these magic numbers were found to be due to the stability of neutral clusters. These results are explained by the intraclus ter electron transfer from an alkali metal atom to AN molecules followed by anionic oligomerization. The results of the calculation for Na(AN) based o n density functional theory also supports this consideration.