Clusters singly charged

The predominant species observed in SIMS spectra are singly charged atomic and molecular ions [51], However, inorganic and organic cluster ions can also be formed. If the sample consists of a simple single-component metal, then clusters such as M, M, etc., are observed in addition to M+ [52], Oxidation of the metal results in formation of MO ", MO/, M Oll", etc. The relative yield of MO+ to M+ depends on the bond dissociation energy of the oxide [52], For a two-component, oxidized metal, clusters of the type M/", M N, MjO, and M N O/ are observed [51]. 

Fig. 12. Mass spectra of singly charged clusters composed of a single Qo molecule coated with a large amount of Na (background subtracted). The even-odd alternation extends up to approximately x = 66. Note that x = 12 does not appear as a magic number in these spectra.

The initial results on the [NaA ] clusters have been extended to the heterocyclic ring species [XAls] (X = Si, Ge, Sn, Pb) bearing a single charge and as a result are not prone to dissociation of an electron like the [Al4] or [Ga4H2] anions [69]. A planar four-membered ring structure is in all cases the most stable structural isomer with Al—Al distances in the range 2.57-2.61 A. 

Wesendrup, R., Hunt, T. and Schwerdtfeger, P. (2000) Relativistic Coupled Cluster Calculations for Neutral and Singly Charged Auj-Clusters./oumol of Chemical Physics, 112, 9356-9362. 

Watanabe H, Iwata S. 1997. Molecular orbital studies of the structures and reactions of a singly charged calcium ions with water clusters, Ca+ (H20)n. JPhys Chem A 101 487-496. 

Recently, Foltin et al. (199 la,b) have reported an unusual metastable decomposition channel in singly charged argon cluster ions involving the loss of a number of argon atoms. The number of argon atoms lost increases from two for Ar to ten... 

In thermal ionization sources, the most abundant ions are usually the singly charged atomic ions. No multiply charged ions can be observed under normal ionization conditions. Cluster ions occur very seldom. However, some metal compounds lead to abundant metal oxide ions. 

---