First-Order Phase Transition in Liquid Water in Terms of the Mode Structure of Absorption Spectrum in the Near-IR Range

摘要

Absorption spectra of liquid water H2O are investigated in the region 4500-5600 cm(-1) at temperatures from -53.0 to +20.3A degrees C. The absorption band is decomposed into component modes at (I) 4700, (II) 4890, (III) 5080, and (IV) 5200 cm(-1) whose centers are shifted slightly with temperature. Modes (II), (III), and (IV) are present in the spectrum of liquid water, whereas modes (I), (II), and (III) are registered in the spectrum of ice. The appearance of the ordered crystalline lattice is characterized by the occurrence of low-frequency mode (I) and by the disappearance of high-frequency component (IV) of the water absorption band in the region 4500-5600 cm(-1). The spectral regions and temperature ranges in which the structure is changed during phase transition are determined.