The application of a new Fourier transform technique to magnetic resonance spectroscopy is explored. The method consists of applying a sequence of short rf pulses to the sample to be investigated and Fourier‐transforming the response of the system. The main advantages of this technique compared with the usual spectral sweep method are the much shorter time required to record a spectrum and the higher inherent sensitivity. It is shown theoretically and experimentally that it is possible to enhance the sensitivity of high resolution proton magnetic resonance spectroscopy in a restricted time up to a factor of ten or more. The time necessary to achieve the same sensitivity is a factor of 100 shorter than with conventional methods. The enhancement of the sensitivity is essentially given by the square root of the ratio of line width to total width of the spectrum. The method is of particular advantage for complicated high resolution spectra with much fine structure.

1.
I. J.
Lowe
and
R. E.
Norberg
,
Phys. Rev.
107
,
46
(
1957
);
compare also A. Abragam, The Principles of Nuclear Magnetism (Oxford University Press, New York, 1961), p. 114.
2.
R. R. Ernst, “Density Operator Theory of Fourier Transform Spectroscopy” (to be published).
3.
The case of a “white” power spectrum is treated in
R. R.
Ernst
and
H.
Primas
,
Helv. Phys. Acta
36
,
583
(
1963
).
4.
The Fourier coefficients are calculated by means of the formula
$Cn = (2/T)12 ∫ 0Tcos(2πnt/T)My(t)dt] = (2T)12(1/c) ∑ k=0c−1cos(2πkn/c)My(Tk/c) (n = 1, 2, ⋯).$
The last equality holds if $My(t)$ does not contain frequencies higher than $c/2T,$ where c is the number of samples within the time T. This is a consequence of the sampling theorem. The factor $2/T$ is chosen such that
$∫ 0TMy2(t)dt = ΣCn2+Sn2,$
where $Sn$ are the corresponding Fourier sine coefficients.
5.
S. Goldman, Information Theory (Prentice‐Hall, Inc., Englewood Cliffs, New Jersey, 1953), p. 230;
and L. S. Schwartz, Principles of Coding, Filtering and Information Theory (Spartan Books, Inc., Baltimore, 1963), p. 136.
6.
R. R.
Ernst
and
W. A.
Anderson
,
Rev. Sci. Instr.
36
,
1696
(
1965
).
7.
W. A.
Anderson
,
Rev. Sci. Instr.
33
,
1160
(
1962
).
8.
S.
Meiboom
and
D.
Gill
,
Rev. Sci. Instr.
29
,
688
(
1958
).
9.
Technical Measurement Corporation (North Haven, Connecticut).
10.
Tally Corporation (Seattle, Washington).
11.
W. A. Anderson (unpublished work);
and H. Primas, 5th European Congr. Mol. Spectry. (June 1961).
12.
City Chemical Corporation (New York).
13.
S.
Bloom
,
J. Appl. Phys.
28
,
800
(
1957
);
and
A.
Szöke
and
S.
Meiboom
,
Phys. Rev.
113
,
585
(
1959
).
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