Intermolecular vibrational study in liquid water and ice by using far infrared spectroscopy with synchrotron radiation of MIRRORCLE 20

Far infrared absorption measurements for distilled water and ice Ih were performed in the frequency range from 20 cm−1 to 1000 cm−1 with Fourier Transform Infrared Spectrometer (FTIR) utilizing SR of a portable synchrotron. Four vibrational bands were separated from measured spectra in liquid water. We found that a peak frequency of 40 ± 1 cm−1 did not depend on the temperature in a range between 10.0 °C and 70.0 °C; however, any low energy excitation modes were not observed in the ice spectrum. It is concluded that this band is caused by collective vibrations specific to the dynamical structure in liquid water.