Abstract
Saito et al have observed anomalous behaviours in the double resonances in metal halides in the early stage of saturational narrowing. They have reported following observations, which remained unexplained.
(1) The resonance line of the traced nucleus (B) becomes asymmetric and simultaneously shows shift, when the frequency of the nucleus (A) irradiated by the strong r.f. field is slightly off-resonant.
(2) In the case of the exact resonance, the intensity of the B-resonance decreases and the line disappears from observation. They called this phenomenon “collapsing”.
(3) In some crystals (e.g. Li F) having short spin lattice relaxation time, anomalous effects (1) and (2) do not appear. Recently Bloembergen and Sorokin have observed a large dispersive polarization of the saturated Cs133 in Cs133 Br81 double resonance by applying a r.f. field precessing near the Br81 resonance. At first sight, above mentioned two phenomena appear to be very different, however, they are closely related to each other. It is the purpose of this paper to propose a general theory unifying the two different situations by taking into consideration the effect of the higher order transitions introduced by Bloembergen in discussing the “Overhauser Induction”.
By using a generalized Solomon equation derived from a density matrix, the behaviours of the coupled spin system is discussed.
