title: Evaporation and deposition of alkyl-capped silicon nanocrystals in ultrahigh vacuum.
abstract: Nanocrystals are under active investigation because of their interesting size-dependent properties and potential applications. Silicon nanocrystals have been studied for possible uses in optoelectronics, and may be relevant to the understanding of natural processes such as lightning strikes. Gas-phase methods can be used to prepare nanocrystals, and mass spectrometric techniques have been used to analyse Au and CdSe clusters. However, it is difficult to study nanocrystals by such methods unless they are synthesized in the gas phase. In particular, pre-prepared nanocrystals are generally difficult to sublime without decomposition. Here we report the observation that films of alkyl-capped silicon nanocrystals evaporate upon heating in ultrahigh vacuum at 200 degrees C, and the vapour of intact nanocrystals can be collected on a variety of solid substrates. This effect may be useful for the controlled preparation of new quantum-confined silicon structures and could facilitate their mass spectroscopic study and size-selection.
authors.forename: Yimin
authors.initials: Y
authors.lastname: Chao
authors.forename: Lidija
authors.initials: L
authors.lastname: Siller
authors.forename: Satheesh
authors.initials: S
authors.lastname: Krishnamurthy
authors.forename: Paul R
authors.initials: PR
authors.lastname: Coxon
authors.forename: Ursel
authors.initials: U
authors.lastname: Bangert
authors.forename: Mhairi
authors.initials: M
authors.lastname: Gass
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Kjeldgaard
authors.forename: Samson N
authors.initials: SN
authors.lastname: Patole
authors.forename: Lars H
authors.initials: LH
authors.lastname: Lie
authors.forename: Norah
authors.initials: N
authors.lastname: O'Farrell
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Alsop
authors.forename: Andrew
authors.initials: A
authors.lastname: Houlton
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Horrocks
mesh_terms: D000478:Alkylation; D003460:Crystallization / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties; D014618:Vacuum
chemical_list: D046911:Macromolecular Substances; D012825:Silicon