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Topic: What is the definition of chemical shift?  (Read 5975 times)

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Offline Winga

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What is the definition of chemical shift?
« on: May 21, 2005, 02:09:53 PM »
I can't find an absolute definition from my reference books?

Anyone could help?
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Offline movies

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Re:What is the definition of chemical shift?
« Reply #1 on: May 22, 2005, 01:21:33 PM »
Here's the IUPAC definition:

http://www.iupac.org/goldbook/C01036.pdf
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Offline Winga

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Re:What is the definition of chemical shift?
« Reply #2 on: May 22, 2005, 01:50:52 PM »
Quote
Resonance lines upfield from SiMe4 have positive, and resonance lines downfield from SiMe4 have negative, d-values.
It means the sign of chemical shift on left hand side is negavite?
So, why we keep using positive?

The definition of chemical shift is that equation only?
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Re:What is the definition of chemical shift?
« Reply #3 on: May 22, 2005, 02:02:37 PM »
No, stuff to the left of Me4Si is positive.

The equation is how the chemical shift is calculated numerically.  The reasons for the chemical shift are the different electronic (and therefore magnetic) environments of the atoms in question relative to an arbitrary standard.
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