Ein Impulsverfahren zum Nachweis sehr schwacher Kernresonanz-Signale und die Messung des magnetischen Kernmoments von¹⁸⁷Osmium

Abstract

By a pulse-technique, rf-irradiation and detection of the NMR-signal are separated in time, and therefore generator-noise can be avoided even at very high rf-field-strengths; this leads to the possibility of broadening the NMR-line by saturation. Using this pulse-technique, the sample is not only irradiated by one frequency but by a whole spectrum. A simultaneous narrow band detection of all these spectral lines is achieved by a time-averaging-computer and by calculating the Fourier-transform of the signal stored there. Relaxation-times of samples with weak NMR-signals can be measured with this averaging-technique too.

The extremely weak and very narrow NMR-line of₁₈₇Os in molten OsO⁴ was detected without paramagnetic additions; a frequency range of 80 kHz had to be scanned, this was done in 4 hours. The magnetic moment of this nucleus previously known only from optical hyperfine structure measurements was determined:$\mu _{187_{Os} } = (0.06432 \pm 0.00003)\mu _N$.