Secondary ion mass spectrometry with C-60(+) and Au-400(4+) projectiles: Depth and nature of secondary ion emission from multilayer assemblies

Alternating nanometric thin layer films made from poly(diallyldimethylammonium chloride), poly(styrene sulfonate) and montmorillonite clay were analyzed with 26 keV C-60(+) (433 eV/atom) and 136 keV Au-400(4+) (340 eV/atom). Secondary ion (SI) emission depth from such thin films was determined to be similar to 6-9 nm with C-60(+) bombardment. Similar depth of emission was also reported with Au-400(4+) projectile impacts [Z. Li, S.V Verkhoturov, E.A. Schweikert, Anal. Chem. 78 (2006) 7410]. The SI spectra contain recoiled C-60 projectile constituents (m/z = 12, 13, 36). They track the compositional variation of the assembled thin layers except for C- and CH- whose abundances appear to correlate with the presence of metal atoms in the topmost layer. (c) 2007 Elsevier B.V. All rights reserved.