TY - JOUR

T1 - Condition for Sudden Passage in the Earth’s-Field NMR Technique

AU - Melton, B. F.

AU - Pollak, V. L.

AU - Mayes, T. W.

AU - Willis, Barton L.

PY - 1995/12

Y1 - 1995/12

N2 - The equation of motiondM/dt= γM × B is solved numerically in order to study the dynamic behavior of the magnetization during the cutoff of the polarizing field in the earth's-field NMR technique. It is assumed that the polarizing field is perpendicular to the earth's field and is reduced to zero linearly in a time short compared to all spin relaxation times. The numerical solution for arbitrary cutoff rates is obtained using the fourth-order Runge-Kutta algorithm and is found to be consistent with a power series solution. It is shown that the magnetization remains within a single octant, and that, for moderate to rapid cutoff, the cutoff rate is related to the cone angle of the subsequent free precession by[formula]Here θcis the complement of the cone angle in radians, γ is the proton gyromagnetic ratio, andB0is the magnitude of the static field (normally, the earth's field) used to detect the free precession.

AB - The equation of motiondM/dt= γM × B is solved numerically in order to study the dynamic behavior of the magnetization during the cutoff of the polarizing field in the earth's-field NMR technique. It is assumed that the polarizing field is perpendicular to the earth's field and is reduced to zero linearly in a time short compared to all spin relaxation times. The numerical solution for arbitrary cutoff rates is obtained using the fourth-order Runge-Kutta algorithm and is found to be consistent with a power series solution. It is shown that the magnetization remains within a single octant, and that, for moderate to rapid cutoff, the cutoff rate is related to the cone angle of the subsequent free precession by[formula]Here θcis the complement of the cone angle in radians, γ is the proton gyromagnetic ratio, andB0is the magnitude of the static field (normally, the earth's field) used to detect the free precession.

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U2 - 10.1006/jmra.1995.0732

DO - 10.1006/jmra.1995.0732

M3 - Article

AN - SCOPUS:6144238284

SN - 1064-1858

VL - 117

SP - 164

EP - 170

JO - Journal of Magnetic Resonance, Series A

JF - Journal of Magnetic Resonance, Series A

IS - 2

ER -