METHOD FOR DETECTING NUCLEAR INDUCTION SIGNALS AND NUCLEAR SPIN ECHO IN SOLID SAMPLES AND PULSED RADIOSPECTROMETER FOR EFFECTING SAME

摘要

1428683 Gyromagnetic spectrometers SPETSIAL KONSTRUKT BJURO INST RADIOT I ELEKTRON AKAD NAUK SSSR 11 June 1973 27704/73 Heading G1N To detect nuclear induction br spin echo signals lying in a given frequency range the signals are fed to a multi-channel frequency analyzer, each channel responding only to a respective portion of the range. The outputs of each channel are recorded in a multi-channel accumulator. In Fig. 1 high frequency pulses generated at 1 are applied to a sample coil 2 and the signals picked up are passed to superhet receiver 3. The if output of the receiver is connected to multi-channel frequency analyzer 5 which is in turn connected to accumulator 6. The superhet signal is also fed to mixer 9 where it is mixed with a reference RF signal supplied by 7 via key 8. This ensures that the pulses supplied by generator 1 are phase coherent. A mechanical drive 4 changes the frequency determining components of the generator I and receiver 3 to scan the desired frequency range stepwise, while programmer 10, which receives clock signals from 7 via a phase adjustor 11, controls this scanning and generator 1 and accumulator 6 to ensure correct recording of the signals within the spin lattice relaxation time of the sample. The analyzer 5 consists of narrow band filters 16 and amplitude detectors 17; in Fig. 2 (not shown) these are replaced by synchronous detectors each having a respective oscillator. Details of the circuitry of the devices 6, 8, 9, 10, 11, 16, 17 of Fig. 1, are given, and also for the detectors and oscillators (20), (21) of Fig. 2, in Figs. 3-7 (not shown).