Pulsed Nuclear Magnetic Resonance: Spin Echoes

Magnetic resonances of protons in various substances are studied by the techniques of polsed NMR and the measurement of spin echoes. Various substances containing protons (water, glycerine, etc.) are placed in a uniform magnetic field and subjected to polses of a transverse 5 MHz rf magnetic field in near resonance with the Larmor precession frequency of the protons.

The spin-lattice and spin-spin relaxation time constants are determined from measurements of the free-induction signals and the spin echoes produced by various combinations of rf polses. Temperature effects are observed in glycerine, and the effects of paramagnetic ions on the relaxation time constants in water are measured. The magnetic moments of the proton and of the fluorine nucleus are derived from the data.

Lab Guide (PDF)

Pulsed nuclear magnetic resonance: spin echoes lab.

Pulsed nuclear magnetic resonance: spin echoes lab. (Image courtesy of Junior Lab staff.)

References

Bloch, F. "Nuclear Induction." The Physical Review 70, no. 7-8 (1946): 460-474.
One of the original papers on magnetic resonance of condensed matter. The majority of current NMR experiments are induction experiments as described by Bloch.

Bloembergen, N., E. M. Purcell, and R. V. Pound. "Relaxation Effects in Nuclear Magnetic Resonance Absorption." The Physical Review 73, no. 7 (1948): 679-712.
The 'other' original paper. Although the actual method used - resonance absorption - is not used very much any more in NMR, this paper has many valuable discussions - especially on relaxation times.

Hahn, E. L. "Spin Echos." The Physical Review 80, no. 4 (1950): 580-594.
The original spin-echo paper. Besides the 'ordinary' echos discussed in great detail, this paper has a thorough description of stimulated echoes which were only sporadically used for the following two decades.

———. "Free Nuclear Induction." Physics Today 6 (November 1953): 4-9.
A 'popular' description of what we now call Hahn echoes. The cover of this particular issue of the journal had the now famous illustration of the racetrack analogy to the spin echoes.

Carr, H. Y., and E. M. Purcell. "Effects of Diffusion on Free Precession in Nuclear Magnetic Resonance." The Physical Review 94, no. 3 (1954): 630-638.
The original paper of what we now call the Carr-Purcell echo sequence. Another paper with a wealth of information (such as even-echo rephasing).

Meiboom, S., and D. Gill. "Modified Spin-Echo Method for Measuring Nuclear Relaxation Times." The Review of Scientific Instruments 29, no. 8 (1958): 688-691.
A short paper with a major modification of the Carr-Purcell sequence. Without such a modification, it is not possible to generate a long train of echoes. This is an early application of a complex multiple-pulse sequence with phase shifts which have become routine.

Melissinos, A. "Magnetic Resonance Experiments." In Chapter 8 of Techniques in Experimental Physics. New York, NY: Academic Press, 1966, pp. 340-361.

Instrumentation and Technique

Ernst, R. R., and W. A. Anderson. "Application of Fourier Transform Spectroscopy to Magnetic Resonance." The Review of Scientific Instruments 37, no. 1 (1966): 93-102.
Here is a general description of how to design and build fast recovery NMR probes and receiving circuits. The quarter-wave line duplexer that is described is still a common way to decouple the receiver and the transmitter from the probe during transmission and reception, respectively.

Other Good References

Stern, Otto. "For his contribution to the development of the molecular ray method and his discovery of the magnetic moment of the proton." Nobel Prize Lecture. Stockholm, 1943.

Pake, George E. "Fundamentals of Nuclear Magnetic Resonance Absorption. I" American Journal of Physics 18, no. 8 (1950): 438-452.

———. "Fundamentals of Nuclear Magnetic Resonance Absorption. II" American Journal of Physics 18, no. 8 (1950): 473-486.

———. "Radiofrequency and Microwave Spectroscopy of Nuclei." Annu Rev Nucl Sci 4 (1954): 33-50.

Bloch, Felix, and Edward Mills Purcell. "For their development of new methods for nuclear magnetic precision measurements and discoveries in connection therewith." Nobel Prize Lecture. Stockholm, 1952.

Pound, R. V. "Nuclear Paramagnetic Resonance." Progr Nuclear Phys 2, no. 21 (1952): 21-50.

Bloembergen, N. Nuclear Magnetic Relaxation: A Reprint Volume. New York, NY: W. A. Benjamin, 1961.

Buy at Amazon Feynman, Richard P., Robert B. Leighton, and Matthew Sands. "Nuclear Magnetic Resonance." In The Feynman Lectures on Physics. Vol. II. Reading, MA: Addison-Wesley, 1963, Section 35-10 to 35-12. ISBN: 9780201020106.

Buy at Amazon Harris, Robin K., and Brian E. Mann. "The Measurement of Relaxation Times." NMR and the Periodic Table. London, UK: Academic Press, 1979, pp. 41-48. ISBN: 9780123276506.

Buy at Amazon Derome, A. E. "Describing Pulse NMR." Modern NMR Techniques for Chemistry Research. Oxford, UK: Pergamon Press, 1987, pp. 85-95. ISBN: 9780080325132.

Buy at Amazon Farrar, T. C. Introduction to Pulse NMR Spectroscopy. Madison, WI: Farragut, 1987, chapters 1-2, and 4, pp. 1-54, 81-95. ISBN: 9780917903045.

Buy at Amazon Freeman, Ray. "Spin Lattice Relaxation." A Handbook of Nuclear Magnetic Resonance. Harlow, UK: Longman, 1988, pp. 251-258. ISBN: 9780582005747.

Selected Resources

A Polse NMR experiment for an undergraduate physics laboratory by Jordan Kirsch and Robert Newman (PDF)

The "Hooray for NMR" Song and "Twinkle Twindle T2*" Song on Science Groove