Kernmagnetische Resonanzsignale in Festkörpern mit zwei verschiedenen Spinsorten

Abstract

In solids containig spins I=1/2 only, the NMR-transients in solids are given approximately by formulas derived earlier¹. They can be extended to solids with a second, but nonresonant kind of spins S using a simple substitution. The results are exact to second order in the pulse distances and include the dependences of the signal amplitudes on experimental parameters e. g. pulse lengths etc. If the phases of the modulation of two 90°-pulses differ by 0° or 90°, a calculation up to the fourth order yields approximations of the shapes of the resulting echoes ². It is shown that the sum of these echo amplitudes in certain cases agree with the shape of the free-induction-decay³ after a single pulse. If the spins S fluctuate rapidly with respect to the Larmor period the echo amplitudes show a strong dependence on variations of the external Zeeman field and the temperature. The results are checked by experiments.