A PULSE-TECHNIQUE FOR DETECTION OF VERY WEAK NMR-SIGNALS AND MEASUREMENT OF NUCLEAR MAGNETIC MOMENT OF 187 OSMIUM

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: {Mathematical expression}. © 1968 Springer-Verlag.