Difference between revisions of "Kratky plot"
KevinYager (talk | contribs) (→See Also) |
KevinYager (talk | contribs) |
||
| (2 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
A '''Kratky plot''' is obtained by plotting [[scattering]] [[scattering intensity|intensity]] as <math>\scriptstyle I(q) \times q^2</math> vs. <math>\scriptstyle q</math> (instead of simply <math>\scriptstyle I(q) </math> vs. <math>\scriptstyle q</math>). This representation divides-out the decay of the scattering, making certain other [[scattering features|features]] more evident. | A '''Kratky plot''' is obtained by plotting [[scattering]] [[scattering intensity|intensity]] as <math>\scriptstyle I(q) \times q^2</math> vs. <math>\scriptstyle q</math> (instead of simply <math>\scriptstyle I(q) </math> vs. <math>\scriptstyle q</math>). This representation divides-out the decay of the scattering, making certain other [[scattering features|features]] more evident. | ||
| − | In particular, a Kratky analysis is often performed on polymer solutions. Here, the shape of the curve in the Kratky plot helps identify the conformation of the polymer chain: | + | In particular, a Kratky analysis is often performed on polymer solutions. Here, the shape of the curve in the Kratky plot helps identify the conformation of the polymer chain: |
| + | * A rise to a plateau indicates an unfolded chain (random coil) | ||
| + | * A distinct peak is indicative of a compact or folded conformation for the chain (in biological studies, this may be a protein in a well-defined/folded state). | ||
| + | * Other conformations can also potentially be distinguished: | ||
| + | ** Pseudo-linear rise for [[Rod-like scaling|rod-like]] conformation | ||
| + | ** High-''[[q]]'' upturn from the plateau indicates worm-like chain | ||
| + | ** In polymer gels, a peak may indicate the presence of inhomogeneities, such as [[Example:Polymer clustering|clustering]]. | ||
| + | ** etc. | ||
| + | |||
| + | ==Practical== | ||
| + | The validity of a Kratky analysis is strongly dependent on data quality. Only with a very careful and representative [[background]] subtraction can the analysis be considered reliable. | ||
==See Also== | ==See Also== | ||
Latest revision as of 08:58, 25 July 2015
A Kratky plot is obtained by plotting scattering intensity as vs. (instead of simply vs. ). This representation divides-out the decay of the scattering, making certain other features more evident.
In particular, a Kratky analysis is often performed on polymer solutions. Here, the shape of the curve in the Kratky plot helps identify the conformation of the polymer chain:
- A rise to a plateau indicates an unfolded chain (random coil)
- A distinct peak is indicative of a compact or folded conformation for the chain (in biological studies, this may be a protein in a well-defined/folded state).
- Other conformations can also potentially be distinguished:
- Pseudo-linear rise for rod-like conformation
- High-q upturn from the plateau indicates worm-like chain
- In polymer gels, a peak may indicate the presence of inhomogeneities, such as clustering.
- etc.
Practical
The validity of a Kratky analysis is strongly dependent on data quality. Only with a very careful and representative background subtraction can the analysis be considered reliable.
