Chemical exchange
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== Introduction == | == Introduction == | ||
| - | Chemical exchange for NMR processes can be classed into three major groups: fast exchange, intermediate exchange and slow exchange. In the equations below k is the [[exchange rate]], and Ω (''[[offset]]'') (omega; majuscule ) is the difference of the rotating frame frequency (<math>\omega_{rot. frame}</math>, omega ;minuscule) from the [[Larmor frequencey]] (<math>\omega_{0}</math>). Then , Ω is given by the expression: <math>[\Omega=\omega_{0}-\omega_{rot. frame}]</math>. The units for the exchange rate and the units for the offset are the same and are hertz or per second. | + | Chemical exchange for NMR processes can be classed into three major groups: fast exchange, intermediate exchange and slow exchange. In the equations below k is the [[exchange rate]], and Ω (''[[offset]]'') (omega; majuscule ) is the difference of the [[rotating frame]] frequency (<math>\omega_{rot. frame}</math>, omega ;minuscule) from the [[Larmor frequencey]] (<math>\omega_{0}</math>). Then , Ω is given by the expression: <math>[\Omega=\omega_{0}-\omega_{rot. frame}]</math>. The units for the exchange rate and the units for the offset are the same and are in hertz or per second. |
== [[Fast Exchange]] == | == [[Fast Exchange]] == | ||
Current revision
Contents |
Chemical Exchange
Introduction
Chemical exchange for NMR processes can be classed into three major groups: fast exchange, intermediate exchange and slow exchange. In the equations below k is the exchange rate, and Ω (offset) (omega; majuscule ) is the difference of the rotating frame frequency (ωrot.frame, omega ;minuscule) from the Larmor frequencey (ω0). Then , Ω is given by the expression: [Ω = ω0 − ωrot.frame]. The units for the exchange rate and the units for the offset are the same and are in hertz or per second.
Fast Exchange
Fast exchange: k >>|Ω1-Ω2|-The exchange rate is much greater than the difference between resonance peak positions.
Intermediate Exchange
Intermediate exchange: k ~|Ω1-Ω2|-The exchange rate is approximately equal to the difference between resonance peak positions.
Slow Exhange
Slow exchange: k << |Ω1-Ω2|-The exchange rate is much less than the difference between resonance peak positions.
References
Keeler, J. (2005) Understanding NMR Spectroscopy, 3rd ed., Wiley.[1][2] 2) Center for Magnetic Resonance and Imaging [3]
