1 / 7

Dynamic Light Scattering

Dynamic Light Scattering. Christine Fernyhough. Why use DLS?. Information on SIZE SIZE DISTRIBUTION SHAPE? CHARGE? of particles in solution Micelles, vesicles, latexes..... unimolecular species? Requires powerful laser!. Experimental set up.

amy-daugherty
Download Presentation

Dynamic Light Scattering

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. Dynamic Light Scattering Christine Fernyhough

  2. Why use DLS? • Information on • SIZE • SIZE DISTRIBUTION • SHAPE? • CHARGE? of particles in solution Micelles, vesicles, latexes..... unimolecular species? Requires powerful laser!

  3. Experimental set up D48 Instrument: Brookhaven BI-200SM goniometer Armes group Beppe’s group? LASER TRAINING REQUIRED!

  4. Diffusion of particles • Brownian motion • Frequency-time measurements of particles moving through a solution: dependent on the diffusion coefficient • Stokes-Einstein Equation Rh – hydrodynamic radius kB – Boltzmann constant T – temperature η – viscosity (solvent) D0 – diffusion coefficient

  5. The measurements The particles in a sample of interest are in a relatively narrow size range and it is expected that the particles move with similar velocities but in different directions. The light scattered from the particles is correlated with respect to time Where g(t) is the autocorrelation function, I is the intensity, t is the time delay, t0 the starting time, and T is the averaging time (this should be as long as possible)

  6. Results

  7. References & Related Techniques • “Brookhaven Laser Light Scattering System” manual (D48) – useful for basic use of instrument and tips on experimental technique • “Laser Light Scattering Basic Principles and Practice” 2nd Ed. Benjamin Chu (Sasha has a copy) • Zeta potential measurements: pH autotitration. Measures charge on particles as well as z-average size (Armes) • Particle sizer (F-floor analytical lab) • People: Christine, Sasha, Adam, Craig, Shaomin......

More Related