Trusted, Bureaucrats
4,228
edits
Changes
Changed the {{warning}} to a {{caution}}.
A major point of confusion in the NMR field is that of the dimensionless and hidden radian unit. This often results in people mistakenly writing Hertz units when inverse seconds (or rad/s) should have been used. This issue can be traced back to the [http://en.wikipedia.org/wiki/International_System_of_Units SI] organisation itself. Specifically the SI supplementary units definitions whereby the assumption is made that if a process is rotational, a physicist should know that radian units are implicit.
== Introduction ==
This concept is quite important for understanding relaxation in NMR or, in fact, any rotational process in physics. It is important for understanding also a follow on from the model-free equations, for reduced spectral density mapping, for SRLS, and for relaxation dispersion. The reason is because relaxation rates are measured in rad[https://smail. As described in [[#SI supplementary units]], the radian unit can be dropped because it is plainly obvious that NMR and relaxation is an angular process and hence radian units are implied (that was sarcastic)gna. Hence R2 can be said to be in units of 1org/public/relax-devel/2007-06/s, but never, ever Hzmsg00012. Also note that because html comprehensive unit analysis of the SI conventions described below, describing the correlation time in Abragam's units does not imply that there are no radian units. But reporting rates as Hz implies no radian units whereas reporting as 1/s instead indicates that radian units are presentrelaxation equations].
== Source ==
</math>
where <math alt="theta''θ(t)">\theta(t)</math> '' and <math alt="phi''ϕ(t)">\phi(t)</math> '' are the time dependent spherical angles in the dimensionless radian units. The time ''t '' is normal time and hence has no hidden radian units. Spherical harmonics are the angular portion of the solution to Laplace's equation and, because it is angular, it is using the radian angular SI unit.
== Rotational correlation times ==
;Quote (page 37)
<blockquote>...T1 relaxation is inversely proportional to correlation time tau_c...</blockquote>
= See also =
[[Category:Theory]]