Abstract

In single crystals the NQ R nutation frequency depends on the relative orientation of the coil and the quadrupole axes. In powders the nutation lineshape is a superposition of spectra from the randomly oriented single crystals, so that powder patterns appear in such experiments if the recon struction is performed by the Fourier transform method. In this paper an alternative reconstruction method of nutation spectra is suggested making use of the Hankel Transform. In this way the nutation spectra are simplified. Singularities arising with experiments for the determination of the asymmetry parameter rj can easily be resolved. In the particular case of an axially symmetric quadrupolar tensor and a hom ogeneous radiofrequency field one can reduce the powder pattern to a single line w ithout heterogeneous broadening with respect to orientation. Further improvement o f the nutation spectra can be achieved by taking advantage of the maximum entropy method, which strongly reduces apodisation and noise problems. Applications of the new data m anipulation techniques to N Q R imaging m ethods published elsewhere and 2D zero-field N Q R spectroscopy are reported.