Secondary ion mass spectrometry with C_(60)~+ and Au_(400)~(4+) projectiles: Depth and nature of secondary ion emission from multilayer assemblies

摘要

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 6–9 nm with C_(60) ~+ bombardment. Similar depth of emission was also reported with Au400 4+ projectile impacts [Z. Li, S.V.Verkhoturov, E.A. Schweikert, Anal. Chem. 78 (2006) 7410]. The SI spectra contain recoiled C60 projectile constituents (m/z = 12, 13, 36). Theytrack 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.