Difference between revisions of "Guinier plot"

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or equivalently,
 
or equivalently,
 
:<math>\ln(I(q)) = \ln(I_0) - (R_g^2/3)q^{2} </math>
 
:<math>\ln(I(q)) = \ln(I_0) - (R_g^2/3)q^{2} </math>
Thus a straight line in a plot of ln(''I'') vs. ''[[q]]''<sup>2</sup> is indicative of Guinier scaling and suggests that a system is essentially monodisperse, and can therefore be used as a means of quality control before further data analysis (e.g. [[Form factor]]). Such an analysis is typically only done with the low-''q'' portion of the data. Linear (Guinier) scaling
+
Thus a straight line in a plot of ln(''I'') vs. ''[[q]]''<sup>2</sup> is indicative of Guinier scaling and suggests that a system is essentially monodisperse, and can therefore be used as a means of quality control before further data analysis (e.g. [[Form factor]]). Such an analysis is typically only done with the low-''q'' portion of the data.
  
 
Smaller particles require measurement of lower ''[[q]]'' for Guinier analysis, as Guinier scaling is only maintained up to a certain maximum ''q'':
 
Smaller particles require measurement of lower ''[[q]]'' for Guinier analysis, as Guinier scaling is only maintained up to a certain maximum ''q'':

Revision as of 17:17, 11 August 2020

Guinier analysis attempts to extract the size-scale for a structure by fitting the scattering to an equation of the form

or equivalently,

Thus a straight line in a plot of ln(I) vs. q2 is indicative of Guinier scaling and suggests that a system is essentially monodisperse, and can therefore be used as a means of quality control before further data analysis (e.g. Form factor). Such an analysis is typically only done with the low-q portion of the data.

Smaller particles require measurement of lower q for Guinier analysis, as Guinier scaling is only maintained up to a certain maximum q:

  • For spherical particles,
  • For elongated particles,

See Also