Notes on Guinier

2011/01/02 // 2 Comments

…well, his famous SAXS analysis method. This documentGuinier_short, copyright Brian Pauw gives a short description and review of the applicability of the Guinier method to polydisperse systems. It also shows, through analysis of simulated data, what q-range should be measured for the Guinier method to be valid. In short, the rule of qmax=1.3/Rg still holds, but Rg in polydisperse systems is the volume-squared weighted Rg of the distribution. This then implies that the Guinier method for polydisperse systems quickly becomes unusable as the required qmax cannot be reached with anything but USAXS systems for polydisperse samples. This text (the linked PDF) is released under copyright (copyright by Brian R. Pauw, 2011) as I may want to include some of this in a later publication. I hope you [...]

Monte-Carlo Code

2010/12/21 // 2 Comments

Hi all, Herewith a preliminary release of the Monte-Carlo code for fitting SAXS patterns. Documentation will follow, as will a movie and more. MCFit_sph.m Check it out and let me know if you have any [...]

Sorry for the delay

2010/12/10 // 0 Comments

Hi all, Sorry for the big wait. It is not over yet, but I am working on it. More posts hopefully soon although I cannot promise a topic. Might be videos, but maybe also the monte-carlo code. The Monte-Carlo thing is almost ready to go, just some documentation left to write. It has become a slow bugger by now, but if you have a fast computer, you have nothing to worry about ;). Limitations: You need good data. and I mean thousands of counts. Millions, if you have them. Also, it only works for dilute, spherical systems. God, I feel like a physicist now… Anywho, for that, it works and it retrieves all information present in your scattering pattern. Check again soon and I may have it up here. And I hope there is a publication to follow as well, as we have to keep the numbers up in this climate. Oh, and if you wonder about my current writing style… I must admit, I have been overdosing on [...]

saxsfit software with documentation, fitting function examples and example data

2010/10/10 // 2 Comments

Hi all, I have made some new software available on the “software” page. This is the saxsfit (yes, terrible name, I know) routine I normally use for fitting SAXS curves to model functions. Nothing special, except that it can also deal with (time)series quite nicely. Also there is documentation for some of the packages. I hope to have the documentation complete for all packages in the future, but for now is still a work-in-progress. Next time, a Monte-Carlo fitting routine, which should come complete with introductory Youtube movie! Cheers! [...]