The Temperature‐Dependent Hydrogen‐Bonding Signature of Lipids Monitored in the Far‐Infrared Domain

Phospholipids are studied by means of Fourier transform infrared (FTIR) spectroscopy in the mid‐ and far‐infrared spectral ranges, thereby establishing the hydrogen‐bonding continuum as a function of the temperature. The well‐known mid‐infrared spectrum of the phospholipid layer clearly shows a temperature‐dependent phase transition. In the far‐infrared region (from 300 to 50 cm^?1), an alternation of the interaction between the phospholipids and water molecules is found. The hydrogen‐bonding network ensemble and bound water molecules can be monitored in this spectral region. The lipid structure is found to strongly influence the intermolecular hydrogen‐bonding interplay. Thus, studies in the far‐infrared region provide significant information—at the molecular level—about the intermolecular hydrogen‐bonding signature of self‐assembled phospholipids.