Electrospray mass spectrometry of semiconductor nanoclusters: Comparative analysis of positive and negative ion mode

There has been a substantial growth in the application of mass spectrometry (MS) methods for the analysis of inorganic materials, due to the inherent sensitivity of mass spectrometry ionization to the specific composition and structure of the analyzed materials. To date, few mass spectrometry studie s have focused on metal-chalcogenide materials, an important class of semic onductor materials at the nanoscale, that exhibit interesting optical and e lectronic properties as a function of size. In this study, we report the ap plication of a correlated electrospray mass spectrometry (ESMS) study betwe en negative-ion and positive-ion mode under low-cone voltage to probe size, composition, and stability of metal-chalcogenide materials at the <1 nm sc ale. This correlation approach provides insight into the ionization behavio r and thermodynamic stability of clusters in the <1.0 nm size domain of the form [Zn-4(SPh)(10)][Me4N](2), [Cd-4(SPh)(10)][Me4N](2), [E4Zn10(SPh)(16)] [Me4N](4), [E4Cd10(SPh)(16)][Me4N](4) (E = S, Se). It is demonstrated that application of low-cone voltage ESMS can be a useful technique for the rapi d analysis of intact solid state nanomaterials when both negative and posit ive ionic modes are analyzed, with a potential for extrapolation to other c lasses of nanoscale materials. (J Am Soc Mass Spectrom 2000, 11, 338-344) ( C) 2000 American Society for Mass Spectrometry.