| 摘要 |
1,241,843. Gyromagnetic resonance spectrometers. VARIAN ASSOCIATES. Aug.20, 1968 [Aug.21, 1967(2)], No.39742/68. Heading G1N. The operating parameters of a gyromagnetic resonance spectrometer 1 are automatically adjusted under the control of a computer 2 which stores in its memory the results of scanning a reference resonance line or whole spectrum for different settings of the operating parameters and derives correction signals which are applied to adjust the operating parameters of the spectrometer. Individual parameters are adjusted as follows:- Field homogeneity. The currents in field homogenizing coils 12, 13 are adjusted to give maximum resonance peak height or maximum area under resonance curve with forced or free precession with the spectrometer locked on to a given reference resonance line or with repetitive scanning of a reference resonance line or spectrum. If free precession is used, a "dephasing pulse" may be applied between successive resonance measurements. Alternatively, the adjustments may be made to give minimum width of peak or maximum peak-to-peak of first wiggle of resonance. Field Stability. The polarizing field is adjusted to give maximum correlation between successive spectra or to superimpose one spectrum on another or to give zero beat frequency between a free precession signal and the r.f. exciting signal or another stable frequency. Radio Frequency Phase. With the spectrometer locked on to a given reference line, the phase of the r.f. transmitter is adjusted so that with pulsed excitation the initial value of the dispersion mode signal is zero or the initial value of the absorption mode signal is a maximum. Alternatively, with repetitive scanning of a line or spectrum, the phase is adjusted to give maximum peak height, maximum peak area or maximum peak symmetry. Radio Frequency Intensity. The intensity of the r.f. transmitter is adjusted to give maximum peak height with repetitive scanning of the spectrum. Scanning Rate. The scanning speed may be slow when the resonance signal is above a given value and fast when the resonance signal is below the given value. Alternatively, correction signals may be derived from side-bands of a given reference line or the rate-of-change of a beat frequency between a strong free induction resonance and the r.f. signal. Filter time-constants. These are adjusted during repetitive scanning of a spectrum to give maximum peak height or twice the minimum peak width or to eliminate wiggles from a reference line. Sample Spinning Rate. This may be adjusted to give maximum energy of a resonance line under pulsed r.f.; or maximum peak height or area or peak-to-peak height of first wiggle during repetitive scanning. Double Resonance Transmitter. The frequency of the double resonance r.f. transmitter is adjusted to give maximum effect and its intensity is adjusted to give maximum peak height when locked on to a reference line. |
