GISAXS - User contributions [en]

Guinier plot

2020-08-13T15:10:49Z

EricSchibli:

A Guinier analysis attempts to extract the size-scale for a structure by fitting the [[scattering]] to an equation of the form:
:<math>I(q) = I_0 \exp \left( - \frac{R_g^2}{3} q^{2} \right) </math>,
or equivalently,
:<math>\ln(I(q)) = \ln(I_0) - (R_g^2/3)q^{2} </math>
Thus a plot of ln(''I'') vs. ''[[q]]''2 can be used to highly the scaling of the scattering. A straight-line in such a plot is indicative of Guinier scaling. Such an analysis is typically only done with the low-''q'' portion of the data. Linear (Guinier) scaling suggests that the system is essentially monodisperse; it can thus be used as a means of quality control before further data analysis (e.g. [[Form factor]]).

==Rule of thumb==
The larger one's particles are, the smaller the minimum ''[[q]]'' must be. One also only expects the Guinier scaling to be maintained up to a certain maximum ''q'':
* For spherical particles, <math>\scriptstyle q_{\mathrm{max}} < 1.3 / R_g </math>
* For elongated particles, <math>\scriptstyle q_{\mathrm{max}} < 0.8 / R_g </math>

==See Also==
* P. Thiyagarajan, T. S. Burkoth, V. Urban, S. Seifert, T. L. S. Benzinger, D. M. Morgan, D. Gordon, S. C. Meredith and D. G. Lynn [http://journals.iucr.org/j/issues/2000/03/01/issconts.html pH dependent self assembly of beta-amyloid(10-35) and beta-amyloid(10-35)-PEG3000] ''J. Appl. Cryst.'' '''2000''', 33, 535-539. [http://dx.doi.org/10.1107/S0021889899014387 doi: 10.1107/S0021889899014387]
* A. V. Smirnov, I. N. Deryabin and B. A. Fedorov [http://scripts.iucr.org/cgi-bin/paper?aj5257 Small-angle scattering: the Guinier technique underestimates the size of hard globular particles due to the structure-factor effect] ''J. Appl. Cryst.'' '''2015''', 48. [http://dx.doi.org/10.1107/S160057671501078X doi: 10.1107/S160057671501078X]
* C. D. Putnam [http://scripts.iucr.org/cgi-bin/paper?vg5047 Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data] ''J. Appl. Cryst.'' '''2016''', 49. [http://dx.doi.org/10.1107/S1600576716010906 doi: 10.1107/S1600576716010906]

Guinier plot

2020-08-13T15:10:13Z

EricSchibli:

A Guinier analysis attempts to extract the size-scale for a structure by fitting the [[scattering]] to an equation of the form:
:<math>I(q) = I_0 \exp \left( - \frac{R_g^2}{3} q^{2} \right) </math>
or equivalently,
:<math>\ln(I(q)) = \ln(I_0) - (R_g^2/3)q^{2} </math>
Thus a plot of ln(''I'') vs. ''[[q]]''2 can be used to highly the scaling of the scattering. A straight-line in such a plot is indicative of Guinier scaling. Such an analysis is typically only done with the low-''q'' portion of the data. Linear (Guinier) scaling suggests that the system is essentially monodisperse; it can thus be used as a means of quality control before further data analysis (e.g. [[Form factor]]).

==Rule of thumb==
The larger one's particles are, the smaller the minimum ''[[q]]'' must be. One also only expects the Guinier scaling to be maintained up to a certain maximum ''q'':
* For spherical particles, <math>\scriptstyle q_{\mathrm{max}} < 1.3 R_g </math>
* For elongated particles, <math>\scriptstyle q_{\mathrm{max}} < 0.8 R_g </math>

==See Also==
* P. Thiyagarajan, T. S. Burkoth, V. Urban, S. Seifert, T. L. S. Benzinger, D. M. Morgan, D. Gordon, S. C. Meredith and D. G. Lynn [http://journals.iucr.org/j/issues/2000/03/01/issconts.html pH dependent self assembly of beta-amyloid(10-35) and beta-amyloid(10-35)-PEG3000] ''J. Appl. Cryst.'' '''2000''', 33, 535-539. [http://dx.doi.org/10.1107/S0021889899014387 doi: 10.1107/S0021889899014387]
* A. V. Smirnov, I. N. Deryabin and B. A. Fedorov [http://scripts.iucr.org/cgi-bin/paper?aj5257 Small-angle scattering: the Guinier technique underestimates the size of hard globular particles due to the structure-factor effect] ''J. Appl. Cryst.'' '''2015''', 48. [http://dx.doi.org/10.1107/S160057671501078X doi: 10.1107/S160057671501078X]
* C. D. Putnam [http://scripts.iucr.org/cgi-bin/paper?vg5047 Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data] ''J. Appl. Cryst.'' '''2016''', 49. [http://dx.doi.org/10.1107/S1600576716010906 doi: 10.1107/S1600576716010906]

Guinier plot

2020-08-11T21:26:28Z

EricSchibli:

A Guinier analysis attempts to extract the size-scale for a structure by fitting the [[scattering]] to an equation of the form:
:<math>I(q) = I_0 \exp \left( - \frac{R_g^2}{3} q^{2} \right) </math>
:<math>\ln(I(q)) = \ln(I_0) - (R_g^2/3)q^{2} </math>
Thus a plot of ln(''I'') vs. ''[[q]]''2 can be used to highly the scaling of the scattering. A straight-line in such a plot is indicative of Guinier scaling. Such an analysis is typically only done with the low-''q'' portion of the data. Linear (Guinier) scaling suggests that the system is essentially monodisperse; it can thus be used as a means of quality control before further data analysis (e.g. [[Form factor]]).

==Rule of thumb==
The larger one's particles are, the smaller the minimum ''[[q]]'' must be. One also only expects the Guinier scaling to be maintained up to a certain maximum ''q'':
* For spherical particles, <math>\scriptstyle q_{\mathrm{max}} < 1.3 / R_g </math>
* For elongated particles, <math>\scriptstyle q_{\mathrm{max}} < 0.8 / R_g </math>

==See Also==
* P. Thiyagarajan, T. S. Burkoth, V. Urban, S. Seifert, T. L. S. Benzinger, D. M. Morgan, D. Gordon, S. C. Meredith and D. G. Lynn [http://journals.iucr.org/j/issues/2000/03/01/issconts.html pH dependent self assembly of beta-amyloid(10-35) and beta-amyloid(10-35)-PEG3000] ''J. Appl. Cryst.'' '''2000''', 33, 535-539. [http://dx.doi.org/10.1107/S0021889899014387 doi: 10.1107/S0021889899014387]
* A. V. Smirnov, I. N. Deryabin and B. A. Fedorov [http://scripts.iucr.org/cgi-bin/paper?aj5257 Small-angle scattering: the Guinier technique underestimates the size of hard globular particles due to the structure-factor effect] ''J. Appl. Cryst.'' '''2015''', 48. [http://dx.doi.org/10.1107/S160057671501078X doi: 10.1107/S160057671501078X]
* C. D. Putnam [http://scripts.iucr.org/cgi-bin/paper?vg5047 Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data] ''J. Appl. Cryst.'' '''2016''', 49. [http://dx.doi.org/10.1107/S1600576716010906 doi: 10.1107/S1600576716010906]

Guinier plot

2020-08-11T21:24:58Z

EricSchibli:

Guinier analysis attempts to extract the size-scale for a structure by fitting the [[scattering]] to an equation of the form
:<math>I(q) = I_0 \exp \left( - \frac{R_g^2}{3} q^{2} \right) </math>
or equivalently,
:<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]]''2 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.

Larger particles require measurement of lower ''[[q]]'' for Guinier analysis, as Guinier scaling is only maintained up to a certain maximum ''q'':
* For spherical particles, <math>\scriptstyle q_{\mathrm{max}} < 1.3 R_g </math>
* For elongated particles, <math>\scriptstyle q_{\mathrm{max}} < 0.8 R_g </math>

==See Also==
* P. Thiyagarajan, T. S. Burkoth, V. Urban, S. Seifert, T. L. S. Benzinger, D. M. Morgan, D. Gordon, S. C. Meredith and D. G. Lynn [http://journals.iucr.org/j/issues/2000/03/01/issconts.html pH dependent self assembly of beta-amyloid(10-35) and beta-amyloid(10-35)-PEG3000] ''J. Appl. Cryst.'' '''2000''', 33, 535-539. [http://dx.doi.org/10.1107/S0021889899014387 doi: 10.1107/S0021889899014387]
* A. V. Smirnov, I. N. Deryabin and B. A. Fedorov [http://scripts.iucr.org/cgi-bin/paper?aj5257 Small-angle scattering: the Guinier technique underestimates the size of hard globular particles due to the structure-factor effect] ''J. Appl. Cryst.'' '''2015''', 48. [http://dx.doi.org/10.1107/S160057671501078X doi: 10.1107/S160057671501078X]
* C. D. Putnam [http://scripts.iucr.org/cgi-bin/paper?vg5047 Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data] ''J. Appl. Cryst.'' '''2016''', 49. [http://dx.doi.org/10.1107/S1600576716010906 doi: 10.1107/S1600576716010906]

Guinier plot

2020-08-11T21:17:02Z

EricSchibli:

Guinier analysis attempts to extract the size-scale for a structure by fitting the [[scattering]] to an equation of the form
:<math>I(q) = I_0 \exp \left( - \frac{R_g^2}{3} q^{2} \right) </math>
or equivalently,
:<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]]''2 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, <math>\scriptstyle q_{\mathrm{max}} < 1.3 R_g </math>
* For elongated particles, <math>\scriptstyle q_{\mathrm{max}} < 0.8 R_g </math>

==See Also==
* P. Thiyagarajan, T. S. Burkoth, V. Urban, S. Seifert, T. L. S. Benzinger, D. M. Morgan, D. Gordon, S. C. Meredith and D. G. Lynn [http://journals.iucr.org/j/issues/2000/03/01/issconts.html pH dependent self assembly of beta-amyloid(10-35) and beta-amyloid(10-35)-PEG3000] ''J. Appl. Cryst.'' '''2000''', 33, 535-539. [http://dx.doi.org/10.1107/S0021889899014387 doi: 10.1107/S0021889899014387]
* A. V. Smirnov, I. N. Deryabin and B. A. Fedorov [http://scripts.iucr.org/cgi-bin/paper?aj5257 Small-angle scattering: the Guinier technique underestimates the size of hard globular particles due to the structure-factor effect] ''J. Appl. Cryst.'' '''2015''', 48. [http://dx.doi.org/10.1107/S160057671501078X doi: 10.1107/S160057671501078X]
* C. D. Putnam [http://scripts.iucr.org/cgi-bin/paper?vg5047 Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data] ''J. Appl. Cryst.'' '''2016''', 49. [http://dx.doi.org/10.1107/S1600576716010906 doi: 10.1107/S1600576716010906]

Guinier plot

2020-08-11T16:13:03Z

EricSchibli:

Guinier analysis attempts to extract the size-scale for a structure by fitting the [[scattering]] to an equation of the form
:<math>I(q) = I_0 \exp \left( - \frac{R_g^2}{3} q^{2} \right) </math>
or equivalently,
:<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]]''2 is indicative of Guinier scaling and suggests that 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

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, <math>\scriptstyle q_{\mathrm{max}} < 1.3 R_g </math>
* For elongated particles, <math>\scriptstyle q_{\mathrm{max}} < 0.8 R_g </math>

==See Also==
* P. Thiyagarajan, T. S. Burkoth, V. Urban, S. Seifert, T. L. S. Benzinger, D. M. Morgan, D. Gordon, S. C. Meredith and D. G. Lynn [http://journals.iucr.org/j/issues/2000/03/01/issconts.html pH dependent self assembly of beta-amyloid(10-35) and beta-amyloid(10-35)-PEG3000] ''J. Appl. Cryst.'' '''2000''', 33, 535-539. [http://dx.doi.org/10.1107/S0021889899014387 doi: 10.1107/S0021889899014387]
* A. V. Smirnov, I. N. Deryabin and B. A. Fedorov [http://scripts.iucr.org/cgi-bin/paper?aj5257 Small-angle scattering: the Guinier technique underestimates the size of hard globular particles due to the structure-factor effect] ''J. Appl. Cryst.'' '''2015''', 48. [http://dx.doi.org/10.1107/S160057671501078X doi: 10.1107/S160057671501078X]
* C. D. Putnam [http://scripts.iucr.org/cgi-bin/paper?vg5047 Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data] ''J. Appl. Cryst.'' '''2016''', 49. [http://dx.doi.org/10.1107/S1600576716010906 doi: 10.1107/S1600576716010906]

Guinier plot

2020-08-11T16:11:14Z

EricSchibli:

Guinier analysis attempts to extract the size-scale for a structure by fitting the [[scattering]] to an equation of the form
:<math>I(q) = I_0 \exp \left( - \frac{R_g^2}{3} q^{2} \right) </math>
or equivalently,
:<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]]''2 is indicative of Guinier scaling and suggests that 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

==Rule of thumb==
The larger one's particles are, the smaller the minimum ''[[q]]'' must be. One also only expects the Guinier scaling to be maintained up to a certain maximum ''q'':
* For spherical particles, <math>\scriptstyle q_{\mathrm{max}} < 1.3 R_g </math>
* For elongated particles, <math>\scriptstyle q_{\mathrm{max}} < 0.8 R_g </math>

==See Also==
* P. Thiyagarajan, T. S. Burkoth, V. Urban, S. Seifert, T. L. S. Benzinger, D. M. Morgan, D. Gordon, S. C. Meredith and D. G. Lynn [http://journals.iucr.org/j/issues/2000/03/01/issconts.html pH dependent self assembly of beta-amyloid(10-35) and beta-amyloid(10-35)-PEG3000] ''J. Appl. Cryst.'' '''2000''', 33, 535-539. [http://dx.doi.org/10.1107/S0021889899014387 doi: 10.1107/S0021889899014387]
* A. V. Smirnov, I. N. Deryabin and B. A. Fedorov [http://scripts.iucr.org/cgi-bin/paper?aj5257 Small-angle scattering: the Guinier technique underestimates the size of hard globular particles due to the structure-factor effect] ''J. Appl. Cryst.'' '''2015''', 48. [http://dx.doi.org/10.1107/S160057671501078X doi: 10.1107/S160057671501078X]
* C. D. Putnam [http://scripts.iucr.org/cgi-bin/paper?vg5047 Guinier peak analysis for visual and automated inspection of small-angle X-ray scattering data] ''J. Appl. Cryst.'' '''2016''', 49. [http://dx.doi.org/10.1107/S1600576716010906 doi: 10.1107/S1600576716010906]