RELAXATION OF ANISOTROPICALLY ORIENTED I=3 2 NUCLEI IN THE MULTIPOLE BASIS - EVOLUTION OF THE 2ND RANK TENSOR IN THE DOUBLE-QUANTUM FILTERED NUCLEAR-MAGNETIC-RESONANCE EXPERIMENT/

Citation
Trj. Dinesen et Bc. Sanctuary, RELAXATION OF ANISOTROPICALLY ORIENTED I=3 2 NUCLEI IN THE MULTIPOLE BASIS - EVOLUTION OF THE 2ND RANK TENSOR IN THE DOUBLE-QUANTUM FILTERED NUCLEAR-MAGNETIC-RESONANCE EXPERIMENT/, The Journal of chemical physics, 101(9), 1994, pp. 7372-7380
Citations number
30
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics, Atomic, Molecular & Chemical
ISSN journal
0021-9606
Volume
101
Issue
9
Year of publication
1994
Pages
7372 - 7380
Database
ISI
SICI code
0021-9606(1994)101:9<7372:ROAOI2>2.0.ZU;2-G
Abstract
The relaxation of an I=3/2 spin system in an anisotropic environment c haracterized by a finite residual quadrupolar splitting omega(q) is mo deled by analytically solving for the density operator from Redfield's relaxation theory. The resulting equations are cast into the multipol e basis in order to describe the tensorial components of the spin dens ity matrix. Included in the relaxation matrix are off-diagonal element s J(1) and J(2), which account for anisotropic systems with omega(q) v alues less than the width of the resonant line. With the Wigner rotati on matrices simulating hard pulses, the response to an arbitrary pulse sequence can be determined. An analytical expression for the response to the double quantum filtered (DQF) pulse sequence (pi/2)-(tau/2)-pi -(tau/2)-theta-delta-theta-AQ for theta=pi/2 is presented, showing exp licitly the formation of a second rank tenser owing only to the presen ce of a finite omega(q). This second rank tenser displays asymptotic b ehavior when the (reduced) quadrupole splitting is equal to either of the off-diagonal spectral densities J(2) and J(1). Line shape simulati ons for omega(q) values of less than a linewidth reproduce the general features of some recently reported Na-23 DQF line shapes from biologi cal systems. Distinct relaxation dynamics govern each of the tensorial components of the resonant signal revealing the influence of the expe rimental variables on the line shape.