References - Bogoliubov Laboratory of Theoretical Physics - JINR

an amorphous NH3 for low and high, positive and negative nuclear polarizations (spin
temperatures). Since magnetic transitions obey the Δ(mp + mn)=±1 selection rule, for
protons Δ(mp)=±1, then Δ(mn)=0 in Eq.(3). At parallel orientation (mp=1/2, mn=1 or
mp=-1/2, mn=-1), the proton energy will be increased by amount hJnm/2; for antiparallel
(mp=-1/2, mn=1 or mp=1/2, mn=-1) it will be decreased by the same amount. In the
order of increasing frequency of the spectrometer, the positive spectra will include νJ−,
νJ0, νJ+ Fermi transitions and the ν+ transition. For negative spectra we have ν− and
νJ−, νJ0, νJ+ transitions, respectively. Since the remote spins interact only by the dipolar
interaction which is independent of the spin permutations, they generate the symmetrical
part of a spectra i.e. ν+ and ν− transitions in Fig. 2a. The proton spins surrounding Fcentres
are undergone by shorter-acting and, hence, the stronger J-interaction [8] which
produces the residual i.e. asymmetrical part of the line. This logic allows one to explain
the left-hand asymmetry of the spectral line at the positive and the right-hand asymmetry
at the negative polarizations. It is clear that the asymmetrical parts of signals, shown
with the solid lines in Fig. 2c, are the squeezed images of nitrogen spins into the proton
line shape. Using Eq. (1), the Table data and the spectral bandwidths in Fig. 1b and
Fig. 2c it isn’t difficult to estimate the amplitude enhancement given by the method:
ANH
AN
= ξ ΔN
(
ΔH
� ∞
0
vHdω/
� ∞
0
vNdω) ≈ 0.3 2.3MHz
0.1MHz · (2150) ≈ 1.5 · 104 , (4)
where ξ ≈0.3 is the asymmetrical contribution in the proton spectrum estimated from
Fig. 2c, ΔN/ΔH is the ratio of nitrogen and proton bandwidths estimated from Fig. 1b
and Fig. 2c and the ratio in the brackets was estimated by Eq. (1) for the proton of 90%
(BH ≈0.9) and the nitrogen of 11% (BN ≈0.11) polarizations both having about the equal
temperatures. The effect can be visualized by a comparison between the noisy routine
spectra in Fig. 1c and the noiseless solid curves in Fig. 2c obtained by our method.
The above consideration has shown that the relative isotope densities of different
quadrupole nuclei in frozen amorphous biological samples can be compared by their
squeezed images in the proton spectrum. The method results in the better accuracy
for isotopic comparison between the normal and cancerous blood samples due to large
amplitude enhancement and the detection at fixed tuning of the NMR-spectrometer.
References
[1] W. Meyer, Nucl. Instr. and Meth. in Phys. Res. A 526, (2004) 12-21.
[2] W.S. Holton and H. Bloom, Phys. Rev. 125, (1962) 89-103.
[3] A. Abragam and M. Goldman, Nuclear Magnetizm: Order and Disorder, (Clarendon
Press, Oxford, 1982) Ch. VI.
[4] Y. Kisselev et al., Nucl. Instr.and Meth. in Phys. Res. A 526, (2004) 105.
[5] B. Adeva et al., Nucl. Instr.and Meth. in Phys. Res. A 419, (1998) 60-82.
[6] W. de Boer, Dynamic Orientation of Nuclei at Low Temperatures, Geneva, CERN,
Yellow Report 74-11, (Nucl. Phys. Division, 13 May, 1974) 1-76.
[7] Y. Kiselev et al., Spin Interactions and Cross-checks of Polarization in NH3 Target.
Int. Workshop SPIN-PRAHA-2008, July 19-26. To be published in EPJ.
[8] H.S.Gutowsky,D.W.McCallandC.P.Slichter,J.Chem.Phys.,21, (1953) 279.
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