Appearance size of poly-anionic aluminum clusters, Aln z-, z = 2–5*

Abundances of Tetra-, Penta-, and Hexa-Anionic Gold Clusters

“…31,[34][35][36][37] While a rather smooth increase of abundance is observed for meta-stable poly-anions as a function of cluster size, calculated lifetimes predict a much sharper slope. 38 In other words, the clusters are less stable with respect to electron emission than predicted from the 0-K field-emission model. In another approach, a thermionic-emission model was applied to describe the experimental data, but the corresponding fit temperatures were considerably above room temperature.…”

“…In another approach, a thermionic-emission model was applied to describe the experimental data, but the corresponding fit temperatures were considerably above room temperature. 38 In turn, assuming clusters with a temperature of 300 K and taking into account tunneling effects, a reduced barrier height for thermionic emission was introduced to describe the data. 38 Though this attempt qualitatively displayed a "field-effect" on thermionic emission, it rather aimed at the importance of internal excitation for an adequate description of electron emission from poly-anionic clusters.…”

“…38 In turn, assuming clusters with a temperature of 300 K and taking into account tunneling effects, a reduced barrier height for thermionic emission was introduced to describe the data. 38 Though this attempt qualitatively displayed a "field-effect" on thermionic emission, it rather aimed at the importance of internal excitation for an adequate description of electron emission from poly-anionic clusters. In the following, we discuss a temperaturedependent field-emission approach for polyanionic metal clusters.…”

Electron attachment to anionic clusters in ion traps

“…Later, di-, tri-, tetra-, and penta-anions of aluminum clusters were observed [14,15,30,31]. With the recent upgrade of the ClusterTrap setup to a 12-T Penning trap, higher charge states for gold clusters have been reported, reaching from tetra-up to hexa-anions [17,18].…”

“…For example, doubly charged anions of carbon and metal clusters were produced either in ion sources by sputtering [4], laser ablation [5][6][7], and electrospray ionization [8], or by electron-transfer reactions [9,10], and in crossed-beam experiments [11]. While also tri-anionic lead clusters were observed by laser ablation [7], even higher charge states have been produced of gold and of aluminum clusters by their simultaneous storage with electrons inside a Penning trap [12][13][14][15][16][17][18]. Recently, production of di-and trianionic gold clusters in a linear radio-frequency quadrupole (RFQ) trap has been demonstrated by exposing stored monoanions to an electron beam [16,17].…”