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Article
Highly Unsaturated Hydrogenated Silicon Clusters, SinHx (n = 3−10, x =
0−3), in Flash Pyrolysis of Silane and Disilane

Steven D. Chambreau, Liming Wang, and Jingsong
Zhang*
Department of Chemistry, University of California,
Riverside, California 92521
J. Phys. Chem. A, 2002, 106 (20), pp 5081–5087
DOI: 10.1021/jp012451r
Publication Date (Web): May 1, 2002
Copyright © 2002 American Chemical Society

Abstract
Bare and partially hydrogenated neutral silicon clusters, SinHx (n = 3−10, x = 0−3), were
produced upon flash pyrolysis of dilute (1%) mixtures of disilane, Si2H6, in Ar and of silane,
SiH4, in He at temperatures above 1000 K. Immediately following the flash pyrolysis of the
precursors (on an 20 μs time scale), the clusters were isolated in a supersonic molecular
beam and detected by single vacuum ultraviolet (VUV) photon (λ = 118.2 or 121.6 nm)
ionization time-of-flight mass spectrometry (TOFMS). The clusters produced were similar for
both precursors with SinHx (n = 4, 6, 7, 10) being significantly populated and Si6Hx being the
most abundant, consistent with the known “magic numbers” of Si clusters. Hydrogen contents
in these SinHx clusters were small with typical hydrogen mole fractions near 10%. The most
stable structures of the Si6H and Si6H2 clusters were identified using ab initio quantum
mechanical methods. Initial thermal decomposition intermediates and reaction products, such
as SiH2, Si2H4, Si2H2, trisilanes, and tetrasilanes, were also observed by TOFMS.