Prediction of the resonant absorption for a polar macromolecule librating in a double potential well

The analytic theory^1,2 is applied to a hemoglobin (Hb) molecule librating in a cosine squared intermolecular potential U(θ); for long-lived librators (with a lifetime of ca. 1 ns) the theory predicts the appearance of narrow microwave loss/absorption lines simultaneously with the low frequency Debye spectrum; comparison is made with the constant field model.