| 摘要 |
1,170, 523. Gyromagnetic spectrometers. VARIAN ASSOCIATES. Feb, 13, 1967 [Feb. 21, 1966], No.6825/67. Heading G1N. In a gyromagnetic side-band resonance spectrometer, in which the applied R.F. or D.C. fields are audio frequency modulated, the resonance condition of the spectrometer is controlled using either an "internal" or "external" reference sample, both being provided. By "internal" is meant a reference sample situated in the same field as the sample under investigation and by "external" a reference sample situated in a different field. The internal reference sample may be intermixed with the sample or may be contained in one chamber of a vial 3, Fig. 2 (not shown), having coaxial chambers or an axial or transverse partition providing the two chambers. It is preferably formed of a substance, e.g. the protons in tetramethylsilane, having a narrow resonance line. The external control sample (13, Fig. 2 not shown), is placed to one side of the internal sample and is surrounded by coaxial coils (14), whose axis is parallel to the D.C. field direction, by which this field may be locally altered. It is preferably composed of the protons in water, having a wide resonance line. In operation, the output of either the internal or external reference sample is fed to an oscilloscope 57, Fig. 3 on which it can be seen whether it is in resonance or not, and to a phase detector 54, the output of which, representative of the dispersion mode resonance signal, is fed to a control 55 by which the D.C. field is regulated to maintain the resonance condition of the spectrometer. Initially the current in the coils (14) is adjusted until the frequencies of resonance of the two reference samples coincide so that, in switching between the two reference samples, the control of the D.C. field is not altered. Thus while the internal reference sample is being removed with the sample under investigation and another sample put in its place, the D.C. field is automatically controlled by the external reference sample, the more exact control provided by the internal reference sample taking effect as soon as the system is switched over without the need to relocate its resonance line. |
