Aluminum-27 nuclear quadrupole

For27A1 the accepted value of the nuclear quadrupole moment is 0.1403(10) X 10"28m2 67, 68). Recently, a new value of 0.1466(10) X 10 28m2 has been suggested, based on values of CQ from microwave spectroscopy 69) and accurate ab initio calculations of the EFG at aluminum in A1F and A1C1 (Kello, V. Sadlej, A. J. Pyykko, P. Sundholm, D. Tokman, M. Chem. Phys. Lett., submitted). 

The rotational dependence of the iodine nuclear quadrupole interaction, the aluminum spin-rotation coupling parameter (C(A1)), and the tensor iD a) as well as scalar ( ) spin-spin coupling constants have been determined for the first time, the remaining parameters (with the exception of D) have been improved in aeeuraey as compared to the literature values [73T6r, 72Wys]. 

To understand the varied chemistry of the aluminas, techniques need to be developed for studying the surface independent of the bulk. Structural and dynamical aspects of the surface do have their origins in the bulk, but the specific details delineating the surface will be different. Clearly it would be advantageous to apply the same surface selective CP methodology developed for the silicas [12-16] to the surface of the aluminas. Before addressing this particular point, however, we need to consider the feasibility of the experiment. Are the aluminum atoms at the surface indeed observable by NMR methods If surface aluminum atoms are observable, we must then recognize that the spin of interest, Al, is not a spin-1/2 nuclide (/ for Al is 5/2) hence Al has a nonzero nuclear electric quadrupole moment. Cross-polarization from protons to a quadrupolar nucleus presents the experimenter with another layer of complication in compari-... 

Precision measurements of hyperfine structure and isotope shifts yield information on nuclear spins, quadrupole moments, and nuclear deformations. The results of these experiments allow tests of nuclear models of the spatial distribution of protons and neutrons in highly deformed nuclei [9.73]. In Fig. 9.23 the hyperfine spectra of different Na isotopes are depicted, which had been produced by spallation of aluminum nuclei by proton bombardment according to the reaction Al(p,3p,xn) Na [9.74]. Such precision measurements have been performed in several laboratories for different families of isotopes [9.72-9.75]. 

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