I agree with Jane and I also recommend Robin K. Harris' book "Nuclear
Magnetic Resonance Spectroscopy" (Longman,1985), page 84, section
3-14: "The origins of relaxation for spin-1/2 nuclei".
Cheers,
Roberto
Roberto R. Gil, Ph.D.
Research Associate Professor and
Director, NMR Facility
Department of Chemistry
Carnegie Mellon University
4400 Fifth Ave
Pittsburgh, PA 15213
412-268-4313
412-268-1061 FAX
rgil_at_andrew.cmu.edu
On Mon, May 9, 2011 at 4:55 PM, Jane Strouse <strousej_at_chem.ucla.edu> wrote:
> In my opinion, the best description of NMR relaxation is given in Neuhaus
> and Williamson's book "The Nuclear Overhauser Effect in Structural and
> Conformational Analysis", VCH, 1989. The first chapter has a subsection
> (1.3) called "The Nature of Relaxation". The text description there is
> extremely clear for getting a feel for what it's all about.
>
> Jane
>
> Dr. Jane Strouse
> Director, UCLA Molecular Instrumentation Center
> (310)-825-9841 - voice
> (310)-825-2280 - fax
> strousej_at_chem.ucla.edu
> http://www.mic.ucla.edu
> Office: Room 1410 Molecular Sciences Building
> Mail: Box 951569
> Shipping: 607 Charles E. Young Dr. East
> Los Angeles, CA 90095-1569
>
>
> -----Original Message-----
> From: Rainer Haessner [mailto:rainer.haessner_at_tum.de]
> Sent: Sunday, May 08, 2011 11:11 PM
> To: ammrl_at_ammrl.org
> Subject: AMMRL: Pictures to explain relaxation
>
> Hi,
>
> I try to start an introduction to relaxation for less NMR experienced
> people.
> The funny thing is: I believed to understand the basics of relaxation.
> Now preparing an explanation as easy as possible for other people I have to
> acknowledge, that simple things are by no means simple to understand.
> At least seen from my point of view. I had a look into many textbooks,
> but found no satisfying answer for two questions.
>
> The basics of relaxation are fluctuating magnetic fields caused by
> mechanical motions of the molecule while fixing the spins by the
> strong external B0 field. A lot of pictures are available to illustrate
> this effect. But ... we need electromagnetism. What is the source for
> the oscillating electrical field?
>
> T2. The vectorial presentation of dephasing is easily explained.
> You are able to understand this assuming local variations of B0.
> That's o.K. for T2 contribution coming from the instrument.
> You cannot take the local oscillations from the molecule, because any
> frequency of these oscillations would be a reason for T2 using
> this model.
>
> On the other hand you can use energy level diagrams and flip
> flop processes and you understand the reason to need very
> low frequent (electro)magnetic oscillations with a fixed frequency.
>
> But is there a possible link between both models?
>
> Maybe it is simply impossible to create pictures especially for the
> T2 issue. But maybe you know an easy answer ...
>
> Greetings
>
> Rainer
>
>
Received on Tue May 10 2011 - 08:07:25 MST