Agricultural mechanization in Asia : AMA

A new assignment of the signals in the 23Na DOR NMR spectra to the different sodium sites in dehydrated NaY zeolite is presented. 23Na DOR and MASNMR measurements of dehydrated NaY, Ca2+-exchanged NaY samples, and NaY samples in which Mo(CO)6 is adsorbed are used for this purpose. Four distinct signals in the 23Na DOR NMR spectra of dehydrated NaY are found: the 1st signal with an isotropic chem. shift of -6 ppm and a quadrupolar coupling const. of 0.4 MHz is assigned to the Na+ cations at site I. The 2nd signal, with an isotropic chem. shift of -12 ppm and a quadrupolar coupling const. of 2.3 MHz, is assigned to the Na+ cations at sites I'/II'. The 3rd and the 4th signals, with isotropic chem. shifts of -4 and 5 ppm and quadrupolar coupling consts. of 4.2 and 4.7 MHz, resp., are assigned to the Na+ cations at sites II and III. [on SciFinder (R)