Relaxation times as a function of temperature in NMR

[neorich]

Good Morning, I have been carrying out some NMR relaxation measurements (T1 and T2), and have found that they have a dependence on the temperature of the sample, for example T1 is small at lower temperatures, and larger at higher temperatures.

Can anyone explain why there is a dependence of these relaxation times on the sample temperature, in other words what is it about the sample properties at different temperatures that changes the values of T1 & T2?

Any help is much appreciated.

Thanks for your help.

neorich2002

 

[marcusl]

T1, the spin-lattice relaxation time, describes dephasing due to magnetic field variations, and energy loss into the bulk material. T2, the spin-spin relaxation time, arises from coupling between neighboring spin systems. Both are temperature dependent, but in general the dependencies can be complex. Sorry I can't help with specifics. Books like Slichter's should describe this is more detail.