ALV Light Scattering Facility

If you would like to use the ALV/DLS/SLS-5000, please schedule ahead of time. Check the above schedule to see when we might be free. Then send e-mail to Tom Kodger to schedule a time to use the ALV. New users are always welcome.

Description

(Partially supported by NSF grant DMR97-04300)
The ALV/DLS/SLS-5000 Compact Goniometer System can be used for a variety of light scattering applications. It is a laser light scattering measurement system for simultaneous angular dependent measurement of dynamic (measurement of time dependent intensity fluctuations) and static (measurement of the total integrated light intensity) light scattering. Most of the samples studied by us are colloidal dispersions in solution, showing both ergodic as well as non-ergodic behaviour (like gels). However, the ALV machine can be used for many other systems like biological (fluctuations in vesicle membrane size) or fluid mechanical (flow, sedimentation) systems. Here incidentally is what the ALV looks like:

DLS/SLS-5000 system allows measurement of autocorrelation functions of scattered light, detected by a single photon detector, and has an on-line data analyzing package, which makes use of various non-linear modeling functions resulting in the calculation of:

  • apparent diffusion constants or distributions (translational and rotational)
  • apparent hydrodynamic size or size distributions if Stokes-Einstein relations are applicable (e.g. particles in suspensions, emulsions)

Also, the software for the ALV/DLS/SLS-5000 is MS-Windows compatible and allows for software-driven angular dependent measurements (there is a motor card on 586 PC which allows you to turn the goniometer arm to the desired angle) and fast on-line analysis. If you are interested, here is a tutorial on the art of light scattering (copyright Barbara Frisken).

Measurement Specifications

  • Particle Size Ranges: <1nm - 2 microns
  • Diffusion Constants: 10^(-4) - 10^(-15) cm^2/s
  • Angular range of detection: 14-152 deg
  • Dynamic range (first channel - last channel of correlator): 25ns - 100s of seconds (the FAST board can actually go to 12.5ns)
  • Laser system: CW pumped laser diode with max I=2W, wavelength=532nm (green), VERTICALLY polarized

If you are doing static measurements, I would strongly encourage you to do a toluene measurement in order to compare Rayleigh ratios (also keeping track of input intensity).

Key People

  • is the contact person for scheduling and general questions.
  • Professor David Weitz is the PI for the facility.

General Links