= Swedness SANS Course - SANS Data Analysis using !SasView =

||= **Table of Contents** =||
|| [#section4 4. Rapid Evaluation of SANS data] ||
||   [#section41 4.1 Background Information] ||
||   [#section42 4.2 Evaluation of the SANS data] ||
||.  [#section43 4.3 Guiner and Kratky Plots] ||

== [=#section4 5. Rapid Evaluation of SANS data] ==

This part of the exercise will use the same real SANS data as the last exercise - taken from a study of surfactant self assembly in deep eutectic solvents (DES). 

If you are continuing directly from the first part of the exercise - "Familiarisation with SasView and Data Handling" you can skip to TASK 17, otherwise start with TASK 10.

{{{
#!div style="background: lightblue"
[=#task10 **TASK 10:**] Restart !SasView

Before starting this part of the exercise, you should have a clean !SasView instance. Quit !SasView and restart it.
}}}

=== [=#section41 4.1 Background Information] ===
Deep eutectic solvents are a class of ionic liquids formed from a hydrogen bond donor and a halide salt. At a certain mixture ratio, the eutectic mixture, the melting point is significantly depressed to values below room temperature.

Here we will examine the self-assembly of a [https://en.wikipedia.org/wiki/Surfactant surfactant], [https://en.wikipedia.org/wiki/Sodium_dodecyl_sulfate sodium dodecyl sulfate (SDS)] in the deep eutectic solvent formed from a 1:2 molar ratio mixture of [https://en.wikipedia.org/wiki/Choline_chloride   choline chloride] and [https://en.wikipedia.org/wiki/Urea   urea].

||Sodium Dodecyl Sulfate||Choline Chloride||Urea||
||[[Image(kemm37_sds.png)]]||[[Image(kemm37_choline.png)]]||[[Image(kemm37_urea.png)]]||

{{{
#!div style="background: lightblue"
[=#task11 **TASK 11:**] If you haven't already done so, download the SANS data :  [attachment:SwednessSasViewTutorialData.zip​] and unzip the file in a known location on your filesystem. Note where you have placed the data.
}}}

You should now have a folder called "Subtracted" containing a set of files named as follows:

[[Image(kemm37_datafileslist.png)]]

The data are SANS curves collected on SANS2D at ISIS and D22 at ILL for samples of protonated (normal) SDS in 1:2 d9-choline chloride:d4-urea. This sample was chosen to give maximum contrast and minimum background signal from incoherent scattering. There were 7 samples with 0.2 wt%, 0.5 wt%, 1.0 wt%, 2.0 wt%, 5.0 wt%, 7.5 wt% and 10 wt% of SDS in the DES with the filenames corresponding to each sample given below:

|| Surfactant Concentration (wt%) || Data File ||
|| 0.2 || 0p2hSDS_dChCldUrea_sub.txt ||
|| 0.5 || 0p5hSDS_dChCldUrea_sub.txt ||
|| 1.0 || 1hSDS_dChCldUrea_sub.txt ||
|| 2.0 || 2hSDS_dChCldUrea_sub.txt ||
|| 5.0 || 5hSDS_dChCldUrea_sub.txt ||
|| 7.5 || 7p5hSDS_dChCldUrea_sub.txt ||
|| 10.0 || 10hSDS_dChCldUrea_sub.txt ||

All the data files have been processed to 1D scattering curves with the solvent background subtracted to leave only the coherent scattering signal on absolute scale.

=== [=#section42 4.2 Evaluation of the subtracted data] ===

You will now load the background subtracted data into !SasView and make a plot in order to visually inspect the scattering curves. 

{{{
#!div style="background: lightblue"
[=#task15 **TASK 14:**] Restart !SasView

Before starting this part of the exercise, you should have a clean !SasView instance. Quit !SasView and restart it.
}}}

{{{
#!div style="background: lightblue"
[=#task16 **TASK 15:**] Click on the "Load Data" button in the Data Explorer

Locate the folder where you placed the data, select all the files in the "subtracted" folder and click "Open" in the dialog.
}}}

The Available Data section of the Data Explorer should look something like:

[[Image(kemm37_loaddata.png)]]


{{{
#!div style="background: lightblue"
[=#task17 **TASK 16:**] Plot the loaded data

Make sure that all the datasets have check marks next to them in the Available Data section of the Data Explorer, as shown above.

Click the "New Plot" button in the Data Explorer.
}}}

A new window should appear with a plot of the data that looks something like:

[[Image(kemm37_dataplot.png)]]

{{{
#!div style="background: lightblue"
[=#task18 **TASK 17:**] Examining the Data.

Visually inspect the data, zooming in and making additional plots as needed.

* What trends do you notice?
* What can you say about the possible solution structure from looking at the data?

}}}




=== [=#section43 4.3 Guiner and Kratky Plots] ===


{{{
#!div style="background: lightblue"
[=#task19 **TASK 18:**] Guiner Analysis

Read the SasView Documentation here : [http://www.sasview.org/docs/user/sasgui/guiframe/graph_help.html] which describes how to change the plotting scale and make linear fits.

Select the lowest concentration data only in the data explorer by ensuring only 0p2hSDS_dChCldUrea_sub.txt has a check mark next to it and click “Send to" fitting.

* Perform a guinier analysis

}}}


{{{
#!div style="background: lightblue"
[=#task20 **TASK 19:**] Kratky Plot

Select the lowest concentration data only in the data explorer by ensuring only 0p2hSDS_dChCldUrea_sub.txt has a check mark next to it and click “Send to" fitting.

* Make a Kratky plot


}}}

== What's Next? ==

You can now move on to the next exercise [wiki:Swedness/Lab1C SLD Calculation and Data Fitting]

== [=#resources Resources] ==

* NIST SLD calculator [https://www.ncnr.nist.gov/resources/activation/]
* NIST Scattering Length and Scattering Cross Section Database [https://www.ncnr.nist.gov/resources/n-lengths/]