Influence of High Orientational Order on the Shape of the Echo Response from a Hahn Pulse Sequence

Authors: van der Struijf C.¹; Nienhuys H.K.¹; Harryvan D.^{1, 2}; Kothe G.²; Levine Y.K.¹

Source: Journal of Magnetic Resonance, Volume 130, Number 2, February 1998 , pp. 253-261(9)

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Abstract:

The amplitude modulations in the simulations of the Hahn echo responses from cholestane spin labels in samples characterized by a high degree of orientational order are shown to arise from the use of “soft” pulses. Soft pulses have a limited spectral range and cover only a small portion of the CW-ESR spectra, so that not all the spins are on-resonance. The magnetization vectors of the off-resonance spins only partially tilted away from the laboratoryzaxis, the direction of the applied static magnetic field. They thus contribute oscillating components to the magnetization in thexyplane. The contribution from the off-resonance spins to the Hahn echo formation is significant in highly oriented samples, but cancels out in samples exhibiting a small degree of order. Experimental echo responses obtained from CSL molecules embedded in rigid matrices of eggPC bilayers and the liquid crystalline materials ZLI and MBBA confirm the theoretical predictions.Copyright 1998 Academic Press.

Language: English

Document Type: Research article

Affiliations: 1: Buys Ballot Laboratory, Debye Institute, Utrecht, 3508 TA, The Netherlands 2: Department of Physical Chemistry, University of Freiburg, Albertstrasse 21, Freiburg, D-79104, Germany

Publication date: 1998-02-01