NMR_history - Varian

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Felix BlochFelix Bloch developed the concept of what he called Nuclear Induction during World War II while working on radar counter measures at Harvard Radio Research Laboratory. This idea of Nuclear Induction later became know as Nuclear Magnetic Resonance.

Felix Bloch and William HansenProfessor Bloch returned to Stanford University after the end of World War II and, with the help of Professor William Hansen, developed plans for the first NMR experiments.

Proton signal from water at 7.76 MHz, sinusoidal field modulation, Bloch, Hansen, and Packard Phys. Rev. 70, 474 (1946)

First NMR signals, 1946The nuclear magnetic resonance of protons in water was first detected in early January 1946 by graduate student Martin Packard, working with Bloch and Hansen F. Bloch, W.W. Hansen, and M. Packard, Nuclear Induction, Phys. Rev 69,127 (1948).

Early NMR Probe and ElectronicsBlochs group was the first to see the NMR signal from water. This early version of an NMR probe was build by William Hansen.

Russell VarianRussell Varian returned to Stanford in July 1946 from his radar work at Sperry Laboratories on Long Island. He believed that nuclear magnetic resonance would be used for more than just the measurement of magnetic field strength and nuclear magnetic moments, and felt that NMR would be even more useful in chemical analysis. Bloch and Hansen were not convinced but requested that he prepare an initial draft of a patent for them.

Bloch-Hansen Patent, 1948With help from Bloch, Hansen, and others, Russell Varian filed a patent in October 1948, entitled Method and Means for Correlating Nuclear Properties of Atoms and Magnetic Fields. Subsequent patents were later issued to include electron spin resonance.

Varian Associates Headquarters in 1948Varian Associates was incorporated in April 1948. One of the stated purposes of the company was to perform research in chemistry, to measure the gyromagnetic ratio of the nuclei of atoms, and to use the gyromagnetic properties of atoms to measure magnetic fields for other purposes. The company boasted $22,000 investment of capital and 6 full time employees.

Chemical Shift Observed in Ethanol, 1951At Stanford in 1951, Jim Arnold, Martin Packard, and Shrinavas Sharmati observed a chemical shift between protons within the same molecule J. Chem. Phys.,19,507 (1951). Russell Varian had long been an advocate of NMR, and the significance of this advance and its potential impact on chemical analysis prompted the initiation of an active NMR applications development effort, headed by a new employee Jim Shoolery.

First NMR Applications Laboratory, 1952The first commercial NMR spectrometer, the Varian HR-30, was installed at Humble Oil company in Baytown, Texas in September 1952. Jim Shoolery, with help from Virginia Royden, opened the Varian NMR Application Lab in January 1953.

First Commercial Technical Information Bulletin on NMR, 1953In July of 1953, Jim Shoolery and Emery Rogers published the first NMR Technical Information Bulletin, which described high resolution NMR and its applications to chemistry.

Sample Spinning, 1954The resolution of NMR was greatly enhanced by the introduction of sample spinning, a concept developed by Felix Bloch and first demonstrated by Wes Anderson and Jim Arnold at Stanford. The drawing shown here is from the patent filed for Bloch by Varian in 1954.

Super High Resolution NMR in 1956Ethanol spectra from 1954 and 1956 show the improvement in resolution brought about by the introduction of sample spinning, higher magnetic field, and the use of the Super Stabilizer to overcome magnetic field jitter.

Field/Frequency Lock, 1956Russell Varian developed the concept of the field/frequency lock utilizing a feedback mechanism. This drawing is from a patent filed in 1956.

The Varian A-60, 1961The Varian A-60 NMR spectrometer, introduced in 1961, was designed for the laboratory chemist. It included calibrated chart paper and a built-in signal integrator.

The HR-100, 1959Iron magnets reached their practical limits for use in NMR at a proton frequency of 100 MHz. The Varian HR-100 was the world leader in chemical shift dispersion and sensitivity from the time it was introduced in 1959 until the first highresolution superconducting NMR magnet was built at Varian in 1962.

The First High Resolution Supercon NMRAfter receiving his PH.D. at Stanford under Professor Block, Harry Weaver joined Varian in 1954. Here he developed the first superconducting NMR magnet using a niobium-titanium alloy. The result was the Varian HR-200, the HR-220 (shown here) and later the HR-300 high resolution NMR spectrometers.

FT NMR Concept, 1956Russell Varian proposed the first applications of Fourier transform principles to NMR as a means to increase the sensitivity of NMR spectrometers. This patent, filed in 1956, described a wideband noise source for NMR signal excitation and heterodyne mixing of the detected signal down to audio. Although several methods were described for the extracting amplitude vs. frequency information, a practical implementation would wait for nearly a decade.

Pulse-Excited High Resolution NMR, 1964This diagram from Wes Andersons engineering notebook, dated June 3, 1964, outlined the idea of pulse-excited high resolution NMR spectroscopy. The practical application of the idea was later implemented by Richard Ernst, working in Andersons laboratory.

FT NMR in Practice, 1965Ernsts apparatus worked well, but was limited by the computing technology of 1965. NMR data was read out of the C-1024 averaging computer on paper tape, transferred to punched cards, and taken to the IBM 7090 computer in an adjacent building. Several days later, after waiting for payroll and factory inventory processing, the Fourier transform was complete.

Sensitivity Advantage of FT NMRThe two spectra of Progesterone, taken in the same total time, were used by Ernst and Anderson to illustrate the sensitivity advantage of Fourier transform NMR.