Fig. 6: Correlation of nano-FTIR peak characteristics. | Nature Communications

Fig. 6: Correlation of nano-FTIR peak characteristics.

From: Subsurface chemical nanoidentification by nano-FTIR spectroscopy

Fig. 6

a Spectral peak positions \(\omega _3^{{\mathrm{max}}}\) and b peak height ratios C of PMMA surface (black symbols) and PMMA subsurface (red symbols) layers are plotted versus the corresponding peak heights \(\varphi _3^{{\mathrm{max}}}\) (experimental data taken from Fig. 3). Arrows indicate decreasing PMMA surface layer thickness t1 (black) and increasing PMMA subsurface layer depth d2 (red). Subsurface PMMA layer thickness is t2 = 59 nm. c, d Calculation results analogous to Fig. 6a, b. In addition, results for PMMA subsurface layers of thicknesses t2 = 15 nm (dotted red line) and t2 = 100 nm (solid red line) are shown. e PMMA nano-FTIR peak positions \(\omega _3^{{\mathrm{max}}}\) and f peak height ratios C are plotted versus the corresponding peak heights \(\varphi _3^{{\mathrm{max}}}\) (data measured at positions A–D in Fig. 1d). b, d, f Gray areas indicate the data spaces that correspond to subsurface material.

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