Water sLED pl.c (Pascale Legault)

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Basic facts about water_sLED_pl

Synopsis: measures diffusion of biomolecules in water

Family: Diffusion experiments

Code authors:

 Pascale Legault

Copyright: P. Legault, lab webpage, University of Montreal


Amplitude of the echo follows the equation:

A = A_0 e^{-(\gamma \delta G)^2(\Delta-\frac{\delta}{3})D_s}

Parameters translate in the following way (bold are vnmr parameters, units are in parentheses):

  • Δ = gdelta (s)
  • δ=gt2 (s)
  • γ gyromagnetic ratio. For 1H γ = 2.675 222 099 x 104 (s-1 Gauss-1)
  • G = gzlvl2 * gcal</sub> (Gauss)
  • gcal is a calibration value that must be obtained for each probe

Data processing

Fit the data to a simple equation:

y = a e^{-b x^2}

It's a Gaussian curve with center at 0, where x = gzlvl2, y = peak intensity.

Then extract Ds from b:

\textstyle D_s = \frac{b}{{(gt2 \cdot \gamma \cdot G_{gzlvl2=1})}^2(gdelta-gt2/3)}

Above, G(gzlvl2=1) is a probe-specific value of field gradient in Gauss per unit gzlvl2.


  1. Altieri, AS and Hinton, DP and Byrd, RA. Association of Biomolecular Systems via Pulsed Field Gradient NMR Self-Diffusion Measurements. Journal of the American Chemical Society 117(28):7566--7567, 1995. BibTeX [sled95]
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