scholarly journals New Method for the Determination of Diffusion Constants from Partially Narrowed Nmr Lines

1980 ◽  
Vol 3 ◽  
Author(s):  
D. Wolf
Keyword(s):  
Relaxation Time ◽  
Free Induction Decay ◽  
Weighted Sum ◽  
Molecular Motions ◽  
Rigid Lattice ◽  
Background Contribution ◽  
Intermediate Temperature Range ◽  
Diffusion Constants ◽  
Free Induction

ABSTRACTThe effect of atomic and molecular motions on the NMR free-induction decay (FID) and lineshape is investigated theoretically in the intermediate temperature range in which the NMR line is only partially narrowed. It is shown that the FID may be decomposed into the weighted sum of a rigid-lattice (background) contribution and an exponentially decaying part containing all the information on the diffusive or reorientational motions in the crystal in terms of the spin-spin relaxation time T2.

Influences of Size and Relaxation Time on Optical Free Induction Decay in a Small Spherical CdSe/ZnS Quantum Dot Quantum Well

2009 ◽  
Vol 64 (12) ◽  
pp. 837-843
Author(s):  
Qianqian Xu ◽  
Duanzheng Yao
Keyword(s):  
Relaxation Time ◽  
Quantum Dot ◽  
Quantum Well ◽  
Free Induction Decay ◽  
Transverse Relaxation Time ◽  
Transverse Relaxation ◽  
Mass Approximation ◽  
Two Factors ◽  
Free Induction ◽  
Decay Signal

The optical free induction decay (OFID) induced by the transition between 1s and 1p state in a small isolated spherical CdSe/ZnS quantum dot quantum well (QDQW) has been studied numerically under the framework of effective-mass approximation. The size and relaxation time-dependent properties of the OFID have been obtained and analyzed. It shows that the OFID-change mechanisms dependent on shell thickness and core size are different. Moreover, the OFID signal decays sharply in amplitude and life as the transverse relaxation time being reduced while the change is slight to the longitudinal relaxation time. By comparing these two factors, we infer that the size mainly influences the amplitude of the decay signal and the delay time is basically determined by the relaxation time

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