Conversion of a Varian 40 Mc/s high resolution nuclear magnetic resonance spectrometer to 80 Mc/s operation

The conversion of a 40 Mc/s Varian nuclear magnetic resonance spectrometer to 80 Mc/s operation is described. The increase in maximum field strength from 12 to 22.5 kG was achieved by the use of conical Permendur pole caps. The factors affecting pole-cap geometry are discussed. Sufficient field homogeneity for the production of high resolution 80 Mc/s hydrogen nuclear magnetic resonance spectra was achieved with Golay electric shim coils. Further stability of the magnetic field, enabling spectra to be recorded on precalibrated chart paper, was achieved by a double audio-frequency modulation technique. Notes are also given on the associated changes required to the electronic circuits.

[1]  E. B. Baker,et al.  Frequency‐Swept and Proton‐Stabilized NMR Spectrometer for all Nuclei Using a Frequency Synthesizer , 1963 .

[2]  R. Freeman,et al.  The Effect of a Second Radiofrequency Field on High Resolution Proton Magnetic Resonance Spectra , 1962 .

[3]  R. Kaiser.  Sideband Oscillator to Facilitate Adjustment of NMR Spectrometer Magnet , 1962 .

[4]  B. A. Evans,et al.  Temperature-controlled permanent magnet for high-resolution nuclear magnetic resonance , 1960 .

[5]  J. Mock.  Broadband Millimeter Wave Paramagnetic Resonance Spectrometer , 1960 .

[6]  L. Bogart,et al.  Wide Range Marginal Oscillator for Operating Nuclear Resonance Probes through Flexible Cable , 1960 .

[7]  H. Kumagai.  On a design of wide range magnet for cyclotron , 1959 .

[8]  G. Tiers.  Reliable Proton Nuclear Resonance Shielding Values by “Internal Referencing” with Tetramethyl-silane , 1958 .

[9]  E. B. Baker,et al.  High Stability Nuclear Magnetic Resonance Spectrograph , 1957 .

[10]  E. R. Andrew,et al.  Ring Shims for Coned Magnet Polecaps , 1952 .

[11]  H. L. Anderson.  Precise Measurement of the Gyromagnetic Ratio of He 3 , 1949 .

[12]  W. W. Hansen,et al.  The Nuclear Induction Experiment , 1946 .

[13]  M. E. Rose.  Magnetic Field Corrections in the Cyclotron , 1938 .

[14]  L. Dreyfus.  Die Berechnung großer Elektromagnete für physikalischchemische Laboratorien , 1931 .

[15]  H. Primas,et al.  High resolution n.m.r.-instrumentation: recent advances and prospects , 1962 .

[16]  Marcel J. E. Golay,et al.  Field Homogenizing Coils for Nuclear Spin Resonance Instrumentation , 1958 .