| 180 | | #!div style="background: lightblue" |
| 181 | | [=#task9 **TASK 9:**] Restart !SasView |
| 182 | | |
| 183 | | Before starting this part of the exercise, you should have a clean !SasView instance. Quit !SasView and restart it. |
| 184 | | }}} |
| 185 | | |
| 186 | | === [=#section31 3.1 Background Information] === |
| 187 | | 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. |
| 188 | | |
| 189 | | 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]. |
| 190 | | |
| 191 | | ||Sodium Dodecyl Sulfate||Choline Chloride||Urea|| |
| 192 | | ||[[Image(tartu_sds.png)]]||[[Image(tartu_choline.png)]]||[[Image(tartu_urea.png)]]|| |
| 193 | | |
| 194 | | {{{ |
| 195 | | #!div style="background: lightblue" |
| 196 | | [=#task10 **TASK 10:**] Download the SANS data : [attachment:TartuSasViewTutorialData.zip] and unzip the file in a known location on your filesystem. Note where you have placed the data. |
| 197 | | }}} |
| 198 | | |
| 199 | | You should now have a folder containing a set of files named as follows: |
| 200 | | |
| 201 | | [[Image(tartu_datafileslist.png)]] |
| 202 | | |
| 203 | | 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: |
| 204 | | |
| 205 | | || Surfactant Concentration (wt%) || Data File || |
| 206 | | || 0.2 || 0p2hSDS_dChCldUrea_sub.txt || |
| 207 | | || 0.5 || 0p5hSDS_dChCldUrea_sub.txt || |
| 208 | | || 1.0 || 1hSDS_dChCldUrea_sub.txt || |
| 209 | | || 2.0 || 2hSDS_dChCldUrea_sub.txt || |
| 210 | | || 5.0 || 5hSDS_dChCldUrea_sub.txt || |
| 211 | | || 7.5 || 7p5hSDS_dChCldUrea_sub.txt || |
| 212 | | || 10.0 || 10hSDS_dChCldUrea_sub.txt || |
| 213 | | |
| 214 | | |
| 215 | | 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. |
| 216 | | |
| 217 | | |
| 218 | | === [=#section32 3.2 Calculating Scattering Length Density] === |
| 219 | | |
| 220 | | The scattering length density is given by |
| 221 | | |
| 222 | | [[Image(tartu_sld.png, 100px)]] |
| 223 | | |
| 224 | | Scattering lengths of relevant elements: |
| 225 | | ||= **Element** =||= **Scattering Length (fm)** =|| |
| 226 | | ||C ||6.646|| |
| 227 | | ||H ||-3.739|| |
| 228 | | ||D ||6.671|| |
| 229 | | ||N ||9.36|| |
| 230 | | ||O ||5.803|| |
| 231 | | ||Cl ||9.577|| |
| 232 | | |
| 233 | | |
| 234 | | Physical properties of the DES components: |
| 235 | | ||= **Component** =||= **Chemical Formula** =||= **Molecular Volume (Å3)** =||= **Density (g/cm3)** =|| |
| 236 | | ||d9-Choline Chloride|| C5H5D9NOCl || 210.77 ||1.17|| |
| 237 | | ||d4-Urea|| CD4N2O ||.75.55 || 1.41|| |
| 238 | | |
| 239 | | |
| 240 | | {{{ |
| 241 | | #!div style="background: lightblue" |
| 242 | | [=#task11 **TASK 11:**] Calculate the scattering length density (SLD) of a 1:2 mole ratio mixture of choline chloride and urea. |
| 243 | | |
| 244 | | Use the information in the table above to calculate the SLD. There are multiple ways to do so, including: |
| 245 | | * Calculating by hand |
| 246 | | * Using a spreadsheet |
| 247 | | * Using the SLD calculator built in to !SasView (in the Tools menu). |
| 248 | | * Using online calculators e.g. [https://www.ncnr.nist.gov/resources/activation/] |
| 249 | | |
| 250 | | Try multiple ways and see if you get the same answer! |
| 251 | | }}} |
| 252 | | |
| 253 | | |
| 254 | | === [=#section33 3.3 Loading and Plotting the data] === |
| 255 | | |
| 256 | | You will now load the data into !SasView and make a plot in order to visually inspect the scattering curves. |
| 257 | | |
| 258 | | {{{ |
| 259 | | #!div style="background: lightblue" |
| 260 | | [=#task12 **TASK 12:**] Click on the "Load Data" button in the Data Explorer |
| 261 | | |
| 262 | | Locate the folder where you placed the data, select all the files in that folder and click "Open" in the dialog. |
| 263 | | }}} |
| 264 | | |
| 265 | | The Available Data section of the Data Explorer should look something like: |
| 266 | | |
| 267 | | [[Image(tartu_loaddata.png)]] |
| 268 | | |
| 269 | | |
| 270 | | {{{ |
| 271 | | #!div style="background: lightblue" |
| 272 | | [=#task13 **TASK 13:**] Plot the loaded data |
| 273 | | |
| 274 | | Make sure that all the datasets have check marks next to them in the Available Data section of the Data Explorer, as shown above. |
| 275 | | |
| 276 | | Click the "New Plot" button in the Data Explorer. |
| 277 | | }}} |
| 278 | | |
| 279 | | A new window should appear with a plot of the data that looks something like: |
| 280 | | |
| 281 | | [[Image(tartu_dataplot.png)]] |
| 282 | | |
| 283 | | {{{ |
| 284 | | #!div style="background: lightblue" |
| 285 | | [=#task14 **TASK 14:**] Examining the Data. |
| 286 | | |
| 287 | | Visually inspect the data, zooming in and making additional plots as needed. |
| 288 | | |
| 289 | | * What trends do you notice? |
| 290 | | * What can you say about the possible solution structure from looking at the data? |
| 291 | | |
| 292 | | }}} |
| 293 | | |
| 294 | | |
| 295 | | === [=#section34 3.4 Fitting the data] === |
| 296 | | {{{ |
| 297 | | #!div style="background: lightblue" |
| 298 | | [=#task15 **TASK 15:**] Fitting the lowest concentration data. |
| 299 | | |
| 300 | | 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. |
| 301 | | |
| 302 | | * Select the model for the structure you predicted for this dataset. |
| 303 | | * How does it compare to the data? |
| 304 | | * Fill in parameters you know and adjust the others to see how close you get to the data. |
| 305 | | * Select parameters to fit and run the fit by clicking "Fit" at the bottom of the fitting panel. |
| 306 | | * Do you get a good fit? |
| 307 | | * Are the parameters you get physically reasonable? |
| 308 | | |
| 309 | | }}} |
| 310 | | |
| 311 | | |
| 312 | | {{{ |
| 313 | | #!div style="background: lightblue" |
| 314 | | [=#task16 **TASK 16:**] Fitting the other data, starting with the 7.5 wt% data set. |
| 315 | | |
| 316 | | Repeat for other concentrations |
| 317 | | * Does the same model fit all data? |
| 318 | | * What is consistent between datasets? What is different? |
| | 177 | #!div style="background: light blue" |
| | 178 | [=#task9 **TASK 9:**] Apply resolution functions to your model |
