Infrared-Active Vibrational Modes in Water
Prepared by D. Meliga and S. Z. Lavagnino
Download the CDF file to view the simulation using the free Wolfram CDF player.
https://sites.google.com/a/learncheme.com/learncheme/simulations/cdf-files/InfraredActiveVibrationalModesInWater.cdf?attredirects=0&d=1
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].

References:
[1] M. Chaplin. "Water Absorption Spectrum." (Nov 20, 2019) www1.lsbu.ac.uk/water/water_vibrational_spectrum.html.
[2] "Water IR Spectrum," NIST Chemistry WebBook, SRD 69. (Nov 20, 2019) webbook.nist.gov/cgi/cbook.cgi?ID=C7732185&Type=IR-SPEC&Index=1.