Figure 4From: Is there evidence for change to collagen within parchment samples after exposure to an X-ray dose during high contrast X-ray microtomography? a multi technique investigationPrincipal components analysis of the NIR spectra of modern parchment samples. (a) A scatter plot of the eigenvalues of basis function 1 versus basis function 2 for the modern samples. (b) First derivative of the Log(1/R) spectra of modern parchment samples. The more intense peak shown at 1900Â nm indicates a steeper slope leading to the water peak at 1947Â nm in the Log(1/R) spectra. Modern control (A), Modern scanned 2.16Â hrs (B), Modern scanned 2.36Â hrs (C) and Modern scanned 12Â hrs (D).Back to article page