Quantitatively interpreting the polarized spectra to extract orientation information requires knowing the Raman tensors for particular vibrational normal modes. Fortunately, the Raman tensor for the (delocalized) Amide I A(0, 0) mode has been determined. It is oriented parallel to the C--O axis of peptide bonds in β-sheet structures. Thus, the Amide I A(0, 0) band is an ideal spectroscopic marker to determine the relative orientation of C--O bonds in amylin 20-29 and Aβ 25-35 fibrils.