| Autor: |
Eykyn, Thomas R., Philp, David J., Kuchel, Philip W. |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 4/15/2003, Vol. 118 Issue 15, p6997, 8p, 1 Diagram, 7 Graphs |
| Abstrakt: |
Semiselective heteronuclear cross-polarization for achieving coherence transfer between a spin I = ½ scalar coupled to a spin S ≥ ½ in isotropic solution is considered. The expansion of the density operator as products of irreducible tensor operators provides a compact formalism for describing cross-polarization involving scalar coupled quadrupolar nuclei. An analytical description of cross-polarization is presented in the limit of strong radio-frequency (rf) fields, with respect to the scalar-coupling constant. Numerical simulations show that reducing the rf field amplitudes does not have a detrimental effect on the efficiency of the transfer provided they are comparable to or greater than the scalar-coupling constant. The use of weak rf fields largely circumvents the reduced efficacy due to Hartmann-Hahn mismatch. Applications of the method for selective observation of scalar-coupled quadrupolar nuclei are considered and experimental results are presented for a mixture of beryllium fluoride complexes. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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