Abstract

The theory of [variable field] NMR relaxometry is notoriously cumbersome. Though the generic quantum mechanical mathematical formulation is relatively simple, its practical applications require the combination of one or more types of spin interactions (I) and one or more types of dynamic processes (D) which modulate the interactions in a stochastic way and thus enable the relaxation. Each pair {I,D} represents a 'relaxation channel' with its own relaxation rate formula. In addition, since relaxation is a second-order process, there are also cross-relaxation formulas for every pair of possible relaxation channels. The total number of potentially useful formulas is therefore extremely large (hundreds, even considering just the most common types of I's and D's).

Comparing such models among themselves one notices that they exhibit common regularities, some of which can be derived from first principles, while others are not yet proved, but apparently confirmed empirically. Such regularities can be useful in complex situations when there is no chance that a convincing relaxation model could be developed, or when there are insufficient resources to develop one.

I would like to present several such conjectures, some universal and some applicable only to homonuclear systems containing no unpaired electrons and no quadrupolar glitches. The talk will of course include supporting argumentation and evidence for the conjectures, and also promote the DLL representation (differential log-log) of NMR dispersion profiles.

Please, cite this online document as:
Sykora S., Seven Conjectures of NMR Relaxometry,
   Talk at 8th FFC NMR Relaxometry Conference, Turin, Italy, May 23-25, 2013, DOI: 10.3247/SL4Nmr13.004.

References

[1] Ferrante G.M., Sykora S., Stelar srl, Technical Aspects of Fast Field Cycling,
     in Advances in Inorganic Chemistry, Vol.57, Editors van Eldik R., Bertini I., Elsevier 2005. (see also)
[2] Sykora S., Cremonini M.A., Laghi L, Fantazzini P., 1H NMR relaxation dispersion profiles of solid BSA,
     Poster at XXXIV Congress on Magnetic Resonance, September 21-24, 2004, Porto Conte (Italy). DOI: 10.3247/SL1Nmr04.002.
[3] Sykora S., Segre A., Capitani D., Proietti N., 1H-NMRD Profiles of Polymers: A Preliminary Experimental Review,
     Poster at 3rd Conference on Fast Field Cycling NMR Relaxometry, May 23-25, 2003, Torino (Italy). DOI: 10.3247/SL1Nmr03.001.

Discussions

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