# Changeset 3031 for Tutorials/SAsize/Small Angle Size Distribution.htm

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Timestamp:
Aug 30, 2017 2:27:07 PM (5 years ago)
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update to 2 frame version

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• ## Tutorials/SAsize/Small Angle Size Distribution.htm

 r2790 Von Dreelevondreele1619601719752014-03-20T16:54:00Z2017-04-19T15:00:00Z12017-08-30T19:25:00Z1412747265 /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:1; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4;

In this tutorial you will determine the size distribution of particles in an alumina polishing powder using data from a constant wavelength synchrotron X-ray USAXS instrument. You will use both Maximum Entropy (MaxEnt) alumina polishing powder using data from a constant wavelength synchrotron X-ray USAXS instrument. You will use both Maximum Entropy (MaxEnt) and Total Non-Negative Least Squares (TNNLS) methods assuming spherical particles. The data were collected from

src="Small%20Angle%20Size%20Distribution_files/image001.png" v:shapes="Picture_x0020_1">

Step 2: Set Limits

mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'>Edit substance/Loadsubstance from the menu; a popup window will appear with possible selections

mso-ascii-theme-font:minor-latin;mso-hansi-theme-font:minor-latin'> substance/Load substance from the menu; a popup window will appear with possible selections

src="Small%20Angle%20Size%20Distribution_files/image003.png" v:shapes="_x0000_i1036">

If desired you can load/add as many substances as you want into this list; you can also delete any of them (except vacuum & unit scatter). The composition, volume occupied by the atoms in the composition and the density are given for each substance. These can each be edited; the other

If desired you can load/add as many substances as you want into this list; you can also delete any of them (except vacuum & unit scatter). The composition, volume occupied by the atoms in the composition and the density are given for each substance. These can each be edited; the other values will change accordingly. If your substance isnt in the list, you can

Many selections are made by default for this analysis; however it is important that an appropriate value is selected for the background. From the high Q end of the data plot

Many selections are made by default for this analysis; however it is important that an appropriate value is selected for the background. From the high Q end of the data plot

normal'>0-4
, that changes the data weighting to Qp. This can change the convergence of the IPG method and yield improved results if one is unsuccessful with the default settings. I got a nice fit with a Q power weight of Qp. This can change the convergence of the IPG method and yield improved results if one is unsuccessful with the default settings. I got a nice fit with a Q power weight of 3 mso-hansi-theme-font:minor-latin'>2.0.

You should save this GSAS-II project as it will be used in the tutorial for fitting small angle scattering data; I used alumina.gpx.

You should save this GSAS-II project as it will be used in the tutorial for fitting small angle scattering data; I used alumina.gpx.

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