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. 2015 Sep 25;6:8394. doi: 10.1038/ncomms9394

Figure 2. NEXAFS spectroscopy and GIWAXS patterns from bar-coated samples.

Figure 2

(a,b) Angle-resolved NEXAFS measurements of a 10 nm (thick) bar-coated film; to probe the degree of in-plane alignment of the polymer transition dipole moments (TDMs), the NEXAFS spectra were recorded as a function of azimuthal angle, rotating the sample with respect to a normally incident X-ray beam. The TDMs of the carbon 1s → π* transitions between 284 to 286 eV are oriented perpendicular to the conjugated backbone, with the dichroism thus providing a direct measure of the degree of polymer backbone alignment at the film surface. Strong dichroism is observed for the peaks corresponding to other TDMs, for example, C 1s to C–H σ* (287.4 eV) and C 1s to C–C σ* (∼292 and 302 eV), indicating strong orientational alignment of side chains as well as the polymer backbone. (c,d) Angle-resolved NEXAFS measurements of a submonolayer (thin) bar-coated sample; (e,f) 2D GIWAXS patterns of bar-coated film (thick) recorded with the X-ray beam incident (e) parallel and (f) perpendicular to the coating direction.