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. Author manuscript; available in PMC: 2011 Apr 1.
Published in final edited form as: Biochim Biophys Acta. 2010 Jan 4;1798(4):788–800. doi: 10.1016/j.bbamem.2009.11.024

Table 1.

IR modes used for analysis of IRRAS spectra

Mode Wavenumber
(cm-1)		 Comments
Lipids
  Acyl chain modes
    CH2 symmetric stretch graphic file with name nihms-164470-t0032.jpg The frequencies of these modes are
qualitative markers of conformational
disorder
    CH2 asymmetric stretch
    CD2 symmetric stretch
    CD2 asymmetric stretch
    CH2 scissoring Orthorhombic phase doublet
Hexagonal or triclinic phase
    CD2 scissoring 1086, 1094
1089		 Orthorhombic phase doublet
Hexagonal or triclinic phase
  Polar region modes
    C=O stretch (ester) 1710-1740 The frequency is sensitive to H-bonding
    C=O stretch (fatty acid) 1690-1740 The frequency is sensitive to protonation
state
    PO2− asymmetric stretch 1220-1250 The frequency is sensitive to hydration and
ion binding
    PO2− symmetric stretch ~1090
Peptide bond modes
    Amide I (mostly C=O
    stretch)		 1610-1690 The frequency is sensitive to secondary
structure and vibrational coupling
    Amide II (N-H in-plane
    bend + C-N stretch)		 1520-1560 Commonly used to monitor H-D exchange.
The frequency is sensitive to secondary
structure
    Amide A (N-H stretch) 3200-3400 Secondary structure sensitivity is limited