INVESTIGATION OF SAMPLES BY N.M.R. TECHNIQUES

摘要

ABSTRACTINVESTIGATION OF SAMPLES BY N.M.R. TECHNIQUESSpatially discriminated information is obtained by appropriateprocessing of data derived from a series of pulsed N.M.R. operationsperformed with a magnetic field exhibiting a linear gradient whosemagnitude is different for each operation, In obtaining a two-dimensional image of spin density distribution, coil sets (5 and 6)are used to generate magnetic field components giving x and ygradients, the former being changed stepwise in magnitude and thelatter being fixed. For each value of x gradient, the sample (1)is irradiated with pulsed r.f. energy, resultant N.M.R. signalsbeing detected by phase-sensitive detectors (19 and 20) whoseoutputs are regularly sampled by A-D converters (25 and 26).Processing of the complete sampled data by a computer (12)involves both Fourier transformation with respect to x gradientmagnitude and Fourier transformation with respect to time. Forsectional images a third coil set (7) is used to generate a componentgiving an alternating z gradient and the irradiation consists of atrain of pulses.