Angular momentum detection of non-linear phenomena in paramagnetic resonance

The angular momentum detection of magnetic resonance is examined. Its features are compared to the Einsteinde Haas experiment and its sensitivity is considered with respect to the conventional techniques of the magnetic resonance. Experimental apparatus is presented in detail. Magnetic resonance is examined theoretically and experimentally when low static and strong r. f. fields are applied. Modified Bloch equations are solved at different ordens of approximation to obtain Bloch-Siegert shift, many-photon transitions and superposition effects of resonances at positive and negative static fields. Many-photon transitions by irradiating the sample with two r. f. fields of different frequencies are examined. These transitions are studied theoretically by the Schrodinger equation solution and by the Bloch equations. The appearance of a transversal static magnetization in the magnetic resonance is considered in detail; this non-linear phenomenon is explained solving the modified Bloch equations and by simmetry considerations. Experiments performed on DPPH by the angular momentum detection technique show an excellent agreement with the theoretical results