Proton spin simulation

These days I started the development of a 3D proton spin system which is influenced by external magnetic fields and radio-frequency pulses - this is useful for understanding the basics of NMR (Nuclear Magnetic Resonance).

I'm using C# with XNA - the models were created on 3dsMax 2010 but since they are very simple, any other program would do, including old versions of Max. Besides that a shader is used
and, of course, linear algebra to do the rotation and precession movements.

Here is one screen-shot (I expect to post others in future):


*I'm currently looking for tips on how to calculate the gyromagnetic ratio for all unpaired protons of all elements in the periodic table, so if you know how to do that send me an e-mail, you'll be welcome.