TY - JOUR
T1 - Nuclear magnetic resonance spectroscopic study of spin-lattice relaxation of quadrupolar nuclei in zeolites
AU - Haase, J.
AU - Park, K. D.
AU - Guo, K.
AU - Timken, H. K.C.
AU - Oldfield, Eric
PY - 1991
Y1 - 1991
N2 - We have obtained the temperature-dependent nuclear magnetic resonance spin-lattice relaxation times of several nonintegral spin quadrupolar nuclei (17O, 23Na, 27Al, and 71Ga) in a series of hydrated zeolites (NaA, NaX, NaY, NaGaY, and NH4-ZSM-5) at 8.45 T. There is no correlation between T1 and the static part of the electric field gradient, which gives rise to the observed nuclear quadrupole coupling constants (e2qQ/h). In all cases, however, we find that relaxation is overwhelmingly dominated by modulation of the time-dependent electric field gradient at the nuclear site due to motion of water molecules and hydrated cations in the zeolite pores. The relaxation times are a function of Si/Al ratio as well as hydration. Our results provide estimates of the Sternheimer antishielding factors (1 - γ∞) in moderate agreement with generally accepted literature values and should be applicable to analysis of the relaxation behavior of other nonintegral spin quadrupolar nuclei in zeolites, e.g., 7Li, 11B, 39K, 87Rb, and 133Cs.
AB - We have obtained the temperature-dependent nuclear magnetic resonance spin-lattice relaxation times of several nonintegral spin quadrupolar nuclei (17O, 23Na, 27Al, and 71Ga) in a series of hydrated zeolites (NaA, NaX, NaY, NaGaY, and NH4-ZSM-5) at 8.45 T. There is no correlation between T1 and the static part of the electric field gradient, which gives rise to the observed nuclear quadrupole coupling constants (e2qQ/h). In all cases, however, we find that relaxation is overwhelmingly dominated by modulation of the time-dependent electric field gradient at the nuclear site due to motion of water molecules and hydrated cations in the zeolite pores. The relaxation times are a function of Si/Al ratio as well as hydration. Our results provide estimates of the Sternheimer antishielding factors (1 - γ∞) in moderate agreement with generally accepted literature values and should be applicable to analysis of the relaxation behavior of other nonintegral spin quadrupolar nuclei in zeolites, e.g., 7Li, 11B, 39K, 87Rb, and 133Cs.
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U2 - 10.1021/j100171a050
DO - 10.1021/j100171a050
M3 - Article
AN - SCOPUS:0011734792
SN - 0022-3654
VL - 95
SP - 6996
EP - 7002
JO - Journal of physical chemistry
JF - Journal of physical chemistry
IS - 18
ER -