Concept of Temperature and the Overhauser Nuclear Polarization Effect

The polarization of nuclei by the Overhauser method is examined for the case of metals. It is shown that the concept of temperature is valid for the conduction electrons if they are viewed form a coordinate system rotating at the electron Larmor frequency $\omega$. Relative to this system, the nuclei precess at nearly $-\omega$, a result equivalent to an enormous nuclear magnetic coupling. The Overhauser result then follows immediately.