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What is the frequency range in #"cm"^(-1)# of #-OH# in water using infrared spectrometry?

1 Answer
Mar 15, 2017

I assume you mean for the #"OH"# stretch of water in the IR region. Organic #"OH"# stretches are typically around the #3200 ~ 3500# #"cm"^(-1)# range.

For water, it's a combination band of the symmetric stretch (#nu_1#), asymmetric stretch (#nu_3#), and symmetric bend (overtone of #nu_2#) motions:

http://www1.lsbu.ac.uk/

http://sdbs.db.aist.go.jp/

This is a Raman spectrum, but this particular vibrational motion is active in both Raman and IR, so this is a suitable proof of the frequency range.

You can see that its range is somewhere around #bb(3200 ~ 3600)# #bb("cm"^(-1))#. This website reports it as #3404.0# #"cm"^(-1)#.