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Nuclear spin dynamics in concentrated solutions and porous media in the presence of inhomogeneous fields.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Nuclear spin dynamics in concentrated solutions and porous media in the presence of inhomogeneous fields.
作者:	Lisitza, Natalia V.
面頁冊數:	183 p.
附註:	Adviser: Warren S. Warren.
附註:	Source: Dissertation Abstracts International, Volume: 64-01, Section: B, page: 0227.
Contained By:	Dissertation Abstracts International64-01B.
標題:	Chemistry, Physical.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3078634
ISBN:	0493995110

Nuclear spin dynamics in concentrated solutions and porous media in the presence of inhomogeneous fields.
Lisitza, Natalia V.

Nuclear spin dynamics in concentrated solutions and porous media in the presence of inhomogeneous fields. [electronic resource] - 183 p.

Adviser: Warren S. Warren.

Thesis (Ph.D.)--Princeton University, 2003.

A joint interaction of dipolar demagnetizing field and radiation damping is studied. It is shown both experimentally and theoretically that under joint action these phenomena an insignificant residual signal triggers exponential resurrection of the spin magnetization, followed by aperiodic spin motion. The deteriorating effects of the aperiodic spin dynamics on the performance of commonly used NMR pulse sequences are demonstrated.

ISBN: 0493995110Subjects--Topical Terms:

226924
Chemistry, Physical.

Nuclear spin dynamics in concentrated solutions and porous media in the presence of inhomogeneous fields.
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245 1 0 $a Nuclear spin dynamics in concentrated solutions and porous media in the presence of inhomogeneous fields. $h [electronic resource]
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520 # $a A joint interaction of dipolar demagnetizing field and radiation damping is studied. It is shown both experimentally and theoretically that under joint action these phenomena an insignificant residual signal triggers exponential resurrection of the spin magnetization, followed by aperiodic spin motion. The deteriorating effects of the aperiodic spin dynamics on the performance of commonly used NMR pulse sequences are demonstrated.
520 # $a The behavior of intermolecular multiple-quantum coherences (iMQCs) in a variety of simple liquids with different chemical and magnetic properties is investigated experimentally and modeled by numerical simulations based on modified Bloch equations. The effects of spin concentration, temperature, intermolecular conformational flexibility, chemical exchange and spin-spin coupling on the formation of iMQCs are examined. It is shown that any process that makes the Larmor frequency time-dependent may interfere with the formation of these coherences.
520 # $a The dynamical processes in blood are explored using DDIF methodology. It is shown that the internal gradients of the magnetic field in blood are mostly contributed by the susceptibility gradient across the membrane of erythrocyte. As a result, the decay of proton magnetization is dominated by the diffusion between red blood cells and plasma. The characteristic time required for the spin to cross the membrane can be determined from the diffusion eigenspectrum.
520 # $a The dynamics of nuclear spins in the presence of the inhomogeneous magnetic field in porous materials is explored. The detailed diffusion behavior of spin magnetization is studied using NMR methodology based on the Diffusive Decay of magnetization in the Internal Field (DDIF). It is shown that spin dynamics can be described in terms of the eigenmodes of spin diffusion and the eigenmode spectrum can be used to characterize the internal space of porous media. The behavior of the diffusion eigenmodes is examined as a function of the spatially dependent encoding phase due to the inhomogeneous internal field. It is shown that in the limit of weak phase encoding the first eigenmode is predominantly excited and the eigenmode spectrum reflects the pore size distribution. In the regime of arbitrary encoding the spectrum can be dominated by the high order modes. The experimental scheme to manipulate the excitation spectrum by exploiting the unique symmetry of eigenmodes is proposed.
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