Experimental Testing of Lateral and Depth Resolution in Imaging Methods

Abstract

Summary: A polymer laminate and a PA-PTFE blend were studied by various imaging methods (FT-IR, Raman, ESEM). Different lateral and depth resolution of the methods were used to gain complementary information on the structure of the materials. Radiation damage caused by the electron beam during ESEM investigation was studied by Raman global imaging.

Use of Environmental Scanning Electron Microscopy to image poly(N-isopropylacrylamide) microgel particles

“…Finally, we must consider possible damage due to radiation and/or charging. This problem has been the focus of several studies [49][50][51]70]. Under normal operating conditions, space charge effects due to positive ions may be considered negligible [51].…”

Vibrational Spectroscopy Imaging in Polymers

“…The profiles at both solvent exposure times in Figure 14. 16 show that the crystallization process is completed before the solvent equilibrium is achieved in the semicrystalline polymer. This observation led to the conclusion that the overall crystallization process is limited by the solvent diffusivity and plasticization of the polymer rather than by the rearrangement of macromolecular chains.…”

“…Wilhelm et al [15,16] insisted on the importance of a combination of IR and electron microscopy for characterization of polymer morphologies. They investigated lateral and depth resolution in FT-IR and Raman imaging in comparison with those in SEM.…”

Nondestructive Three-Dimensional Analysis of Layered Polymer Structures with Chemical Imaging

“…The method is especially suitable for nondestructive characterization, without staining or labeling of the sample, since vibrational spectroscopy is based on the inherent molecular vibrations. The combination of a Fourier transform infrared (FT-IR) spectrometer with a focal plane array (FPA) detector provides a technique for simultaneous imaging of the lateral distribution of the chemical sample constituents. − The capability of imaging the sample composition with chemical contrast is important for a deeper understanding of processes and structures of complex materials. − Attenuated total reflection (ATR) spectroscopy is based on the shallow penetration of the evanescent field into the sample in contact with the internal reflection element (IRE), which has been shown to be advantageous for minimal sample preparation and spectral artifacts. − The exponential decay of the electric field ( E ) of the evanescent wave into a weakly absorbing sample is given by the depth of penetration ( d p ) and is dependent on the matching of refractive indices of the IRE ( n 1 ) and the sample ( n 2 ) as well as the wavelength (λ) and the angle of incidence (θ) of the light E = E 0 normale false( − z d p false) 2em d normalp = normalλ 2 normalπ n 1 sin 2 ( θ ) − ( n 2 n 1 ) 2 …”