Department of Electronic Engineering, Okayama University of Science
Abstract
The theory of multiphoton processes in solids by a rotary-saturation method in NMR have been proposed by us. In this paper, we apply the theoretical ideas to fluorine nuclei in a CaF_2 single crystal and analyse the experimental results by the theory. We found evidence that (1) the experimental results of multiphoton processes can be explained fundamentally by the theory but cannot be fully ; (2) one type of single spin-n photon transitions is taking place, but another type of two spin-n photon transitions is not confirmed yet in this crystal ; (3) the linewidths of the multiphoton absorptions are extremely narrow at the magic angle but do not completely vanish because of the presence of a perturbing field ; (4) the effects of the energy level mixing through the dipole-dipole interactions on the multiphoton transitions are negligible over a wide range around the magic angle ; (5) the inhomogeneity of the rf field used to quantize the spin system in the rotating frame affects considerably the results of the rotary-saturation experiments
