Spin Echoes from Broad Resonance Lines with High Turning Angles

The generation of spin-echo signals in wide resonance lines for which the rf field intensity $H_1\ll \mathrm{linewidth}$ is discussed. Particular attention is given to the case in which the spins turn by angles greater than 360° during the rf pulses. Inhomogeneities in $H_1$ lead to a considerable simplification of the expressions used to compute the echo wave form. Experimental wave forms obtained for electron spins in (Ca,Nd)W${\mathrm{O}}_4$ are compared with calculated results.