1 / 10

Light Scattering Techniques

Light Scattering Techniques. …and what they can do for. You!. Tom Caremans 24/10/2005. Equipment. Laser. Detector. Sample. Qué?. Scattering. Dynamic Light Scattering. Static Light Scattering. INTENSITY (and don’t you forget that!). R h. R G Mol Weight (M w ).

boydc
Download Presentation

Light Scattering Techniques

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Light Scattering Techniques …and what they can do for You! Tom Caremans 24/10/2005

  2. Equipment Laser Detector Sample

  3. Qué? Scattering Dynamic Light Scattering Static Light Scattering INTENSITY (and don’t you forget that!) Rh RG Mol Weight (Mw) Relaxation time of the different modes DIFFUSION COEFFICIENT of different modes You measure a collective!!

  4. DLS: basic formula’s Remember! : I~m² so: I~D6

  5. What can DLS tell you?

  6. Be careful with DLS data!

  7. DLS and silicalite formation Occurrence of slow phases?? • Twomey, Thompson, Zeolites 14, 1994 • Schoeman, Zeolites 18, 1997 In-situ at 105° (full ns, 125°C) Slow phases were systematically cut out!!!

  8. However… Diluted CS shows a different story when measured in-situ CS: H2O 1:9

  9. Ex-situ vs In-situ; concentrated vs diluted Undiluted CS In-situ: regular case No slow modes visible Ex-situ: slow modes visible That disappear after a certain moment Slow modes appear upon cooling?? Diluted CS Upon heating at 55-60°C slow modes appear Reversibly disappear when cooling Is this the same process happening? More analysis/measurements needed

  10. Books & Texts • No “DLS for dummies” available • The DLS Bible: Robert Pecora, Bruce Berne, Dynamic Light Scattering • SLS: Charles Johnson, Laser Light Scattering, easy to read

More Related