DLS/SLS for turbid systems (ULUND)
Light Scattering
Description
The instrument from LS Instruments is used for simultaneous dynamic and static light scattering with transparent and turbid samples. It is equipped with a Cobolt Laser light source, wavelength λ0=660.0 and a maximum power of 100 mW. The sample is filled into cylindrical glass cells of a diameter of 5 or 10 mm or 10 mm square cells and placed in the temperature controlled index-matching bath. The scattered light is detected within an angular range of 15 to 150° by two efficient Avalanche Photo Diodes and processed by a LSI correlator in a 3D cross-correlation configuration. In aqueous samples we have access to scattering vectors 0.0034 ≤ q ≤ 0.025nm-1. The apparatus is equipped with a sample goniometer to characterize non-ergodic samples.
The instrument is typically used for:
- Molecular weight determination (Zimm plots).
- Particle form factor determination.
- Static and dynamic structure factor measurements for strongly interacting dilute and concentrated systems.
- Measurements with non-ergodic samples
- Particle sizing
Possible instrument configuration
The instrument can be run in two different modes:
- Cross-correlation: Two scattering experiments are carried out simultaneously with the same scattering volume. The signals are cross-correlated by the two detectors isolating single scattering from undesired contributions from multiple scattering.
- Pseudo cross-correlation: Standard DLS and SLS measurements are performed when analyzing transparent solutions. This allows working with very short lag times and recovering the “ideal” intercept of 1 as well.
Multiangle 3D-Goniometer
The instrument allows time-resolved measurements of dynamic and static light scattering in transparent and turbid samples using the technique of 3D cross-correlation at four angles simultaneously. The apparatus is equipped with a diode-pumped solid-state laser (wavelength λ0=532 nm) with a maximum power of 200 mW. The sample is filled into cylindrical glass cells of a diameter of 5 or 10 mm or square cells with diameter 10 mm and placed in the temperature controlled index-matching bath. The scattered light is detected within an angular range of 10 to 150° by two photomultiplier tubes at each angle and processed by a Flex correlator in a 3D cross-correlation configuration. Thus four intensity correlation functions are obtained simultaneously, one for each scattering angle measured. In aqueous samples we have access to scattering vectors 0.0027 ≤ q ≤ 0.031nm-1.
The instrument is typically used for:
- Molecular weight determination (Zimm plots).
- Particle sizing via hydrodynamic radius.
- Particle form factor determination.
- Static and dynamic structure factor measurements for strongly interacting dilute and concentrated systems.
The instrument is run in cross-correlation mode: Two scattering experiments are carried out simultaneously with the same scattering volume. The signals are cross-correlated by the two detectors isolating single scattering from undesired contributions from multiple scattering.
Local Contacts
- Dr. Peter Holmqvist
