Infrared-Active Vibrational Modes in Water
Prepared by D. Meliga and S. Z. Lavagnino
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This Demonstration shows the fundamental vibrations of the water molecule: symmetric stretch, asymmetric stretch and bending. Any vibration of the molecule is a combination of these normal modes. Also, in liquid water, rotations may cause an infrared absorption with motions restricted by hydrogen bonds. As a consequence of these librations, a broad absorption band occurs at lower wavelengths [1].

[1] M. Chaplin. "Water Absorption Spectrum." (Nov 20, 2019)
[2] "Water IR Spectrum," NIST Chemistry WebBook, SRD 69. (Nov 20, 2019)