Electrical conductivity during XPS of heated PMMA: detection of core line and valence band tacticity effects
✍ Scribed by Beamson, G.; Clark, D. T.; Law, D. S-L.
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 171 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0142-2421
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✦ Synopsis
Electrical conductivity during the XPS of ¿100 nm thick Ðlms of poly(methyl methacrylate) (PMMA) on silicon was induced by heating to above 100ÄC. Rapid x-ray-induced depolymerization set in at about the same temperature. The electrical conductivity allowed acquisition of high-resolution core line and valence band spectra from s-and i-PMMA, free of di †erential charging e †ects. Within a time-scale of ¿25 min the depolymerization did not a †ect the appearance of the spectra. The presence of methoxy groups at the uppermost surface of the two heated samples was conÐrmed by angle-dependent XPS, with an indication of a higher surface concentration of such groups for the s-polymer. At ambient temperature the valence band spectra of the two stereoisomers were identical, but when heated to above 100ÄC a di †erence of ¿0.15 eV developed in the O 2s binding energies ; this is interpreted as being due to preferential crystallization of the s-polymer.