Depth profiling of polymer films with grazing-incidence small-angle X-ray scattering

Abstract

A model-free method of reconstructing depth-specific lateral scattering from incident-angle-resolved grazing-incidence small-angle X-ray scattering (GISAXS) data is proposed. The information on the material which is available through variation of the X-ray penetration depth with incident angle is accessed through reference to the reflected branch of the GISAXS process. Reconstruction of the scattering from lateral density fluctuations is achieved by solving the resulting Fredholm integral equation with minimal a priori information about the experimental system. Results from simulated data generated for hypothetical multilayer polymer systems with constant absorption coefficient are used to verify that the method can be applied to cases with large X-ray penetration depths, as typically seen with polymer materials. Experimental tests on a spincoated thick film of a blend of diblock copolymers demonstrate that the approach is capable of reconstruction of the scattering from a multilayer structure with the identification of lateral scattering profiles as a function of sample depth.

Understanding how excess lead iodide precursor improves halide perovskite solar cell performance

“…5 , which shows Miller indices for a FAPbI 3 thin film). In addition, this analysis technique can provide investigation of the local crystal phase distribution as a function of film depth by varying the Grazing Incident X-ray (GIX) angle (°) 24 . In Fig.…”

“…Two-dimensional GIWAXS 2 dimension (2D) patterns were recorded with a 2D CCD detector (Rayonix MX 225-HS, USA). Diffraction angles were calibrated by a pre-calibrated sucrose (Monoclinic, P2 1 , a = 10.8631 Å, b = 8.7044 Å, c = 7.7624 Å, b = 102.938°) 24 and the sample-to-detector distance was 246.4 mm. The samples were exposed to X-ray beam energy of 11.6 keV for only 10 s to prevent damage.…”

Rapid ordering of block copolymer thin films

“…One can thus compare the structure at the surface vs. within a film, resolving the ambiguities inherent to AFM and SEM. With some care, one can more gradually vary the incident angle, to reconstruct the structure as a function of film depth (rather than simply the average order through the film) [47,350,[353][354][355][356][357]. GISAXS has thus emerged as a powerful means for studying nanostructured soft materials, including studying them in-situ during assembly or conversion; block-copolymers have been extensively studied in this way [358][359][360][361][362][363][364][365].…”

Adsorption of cationic polyacrylamide at the cellulose–liquid interface: A neutron reflectometry study

“…The most intense reflections of cellulose II occur at q = 1.5 Å À1 , there is no evidence of cellulose II diffraction peaks [27]. Within the range of depths probed by the evanescent X-ray beam [28], the cellulose film is completely and homogenously amorphous. GIWAXS measurement of the cellulose nanocrystal film revealed high crystallinity (Fig.…”