Chemical modification of fluorinated self-assembled monolayer surfaces using low-energy ion beams for halogen and pseudohalogen transfer

✍ Scribed by Shen, Jianwei; Grill, Verena; Evans, Chris; Cooks, R. Graham

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 171 KB
• Volume: 34
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199904)34:4<354::aid-jms782>3.0.co;2-4

✦ Synopsis

Isocyanatosilane-derived cations, (n = 1-4) were mass-selected and reacted with Ñuorinated self-Si(NCO) n ', assembled monolayer (F-SAM) surfaces at low collision energy ( AE 100 eV). Examination of the scattered products revealed a variety of reactions from simple Ñuorine atom abstraction (e.g. formation of SiF') to halogenpseudohalogen exchange products (e.g. formation of and from Bare SiF(NCO)

Si'r eacts predominantly by single F-atom abstraction, but small amounts of and were also observed. SiF 2 '~SiF 3 ' The correlation of reactivity with thermochemistry and the role of the electronic conÐguration of projectile ions in multiple F-atom abstraction processes are discussed. Chemical modiÐcation of the F-SAM surface itself was shown to be a consequence of the ion-surface collisions. For example, in situ chemical sputtering analysis of F-SAM Xe's urfaces exposed to ion beam bombardment revealed the presence of (m/z 92). This result Si(NCO) n ' CF 2 NCO' suggests that NCO groups are incorporated into the Ñuorocarbon chains at the surface, probably via a pseudohalogen-by-halogen exchange mechanism. Surface modiÐcation was also achieved using the dicyanatochloromethyl cation, Prolonged reactive collisions of upon a F-SAM surface led to the incorp-C(CN) 2 Cl'. C(CN) 2 Cl' oration of both chlorine atom and cyanato groups into the surface, and these were released as (m/z 76) CF 2 CN' and (m/z 85) on sputtering analysis. Isotopic labeling experiments conÐrmed Cl substitution into the CF 2 Cl' Xe's urface Ñuorocarbon chains.