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Unformatted text preview: V/vis spectroscopy:
UV/vis absorption spectra in solution tend to be broad
without well-defined fine structure. They are therefore
seldom useful in identifying an unknown compound.
UV/vis absorption is sensitive and precise, which
suits it for quantitative analysis of known species.
(i.e., UV/vis addresses “How much?” See Labs 4, 5) How chemists use IR spectroscopy:
The IR spectrum is typically rich in transitions that are sharper
than those in the UV, which provides a fingerprint of the molecule.
IR spectra are therefore quite useful for identification purposes.
IR absorption is generally less sensitive and less precise
than UV/vis. IR spectra are generally used for qualitative analysis.
(i.e., What is it?) 14 7 Not everything that is clear and colorless
is the same: how can we tell them apart?
Although we often cannot see differences in
organic materials with our eyes, we can
often characterize them if we look for
absorption in the IR
– When do molecules absorb IR?
• When a change...
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This note was uploaded on 01/24/2014 for the course CHEM 115 taught by Professor L during the Fall '02 term at Purdue University-West Lafayette.
- Fall '02