Nuclear magnetic resonance dipole dipole interaction

[xfshi2000]

Hi all:
One system consists of two neutrons. both spin magnetic moments are 1/2. At a instant time, neutron 1 locates position 1 and neutron 2 is in position. As we know, spin magnetic moment is kind of dipole moment. They can generate magnetic field (not electric field). The interaction can be described by m1*m2/r^3. m1/m2 stand for spin magnetic moment of spin1 and spin2. My question is that:
1)How fast spin2 can "feel" the magenetic field generated by spin1 when spin1 keep changing position due to thermal fluctuation?

Because spin1 moves at all times, spin2 see a continual change of magnetic field.
2) Is the change of magnetic field inducing the transition on spin2 if spin2 is in a fixed position?

3) Is the interaction between change of magnetic field and spin2 magnetic moment still dipole dipole interaction?

thanks
xf

 

[azntoon]

1)The speed at which spin2 feels the magnetic field generated by spin1 is the speed of light, since the magnetic field is a form of electromagnetic radiation. 2)Yes, the changing magnetic field could induce transitions on spin2 if it is in a fixed position. 3)Yes, the interaction between the changing magnetic field and spin2 magnetic moment is still dipole-dipole interaction.