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Photon correlation spectroscopy laboratory

The laboratory probes the fast and slow relaxation dynamics in colloidal/glassy samples with the possibility to go at high temperatures. The lab is equipped with a DLS spectrometer (LS Instruments) and an home-made setup optimized for high-temperature photon correlation imaging (PCI) measurements.

Dynamic Light Scattering spectrometer in 2D/3D geometry

This LS Instrument device is capable to perform both dynamic and static light scattering experiments. The 2D pseudo mode allows to suppress after-pulse of the APD making the instrument efficnet in detection of fast dynamics (up to hundreds of nanoseconds). The additional 3D mode is a powerful tool to mitigate the effect of multiple scattering phenomena on turbid samples.
The instrument is widely employed to calculate hydrodynamic radius, characteristic decay time and polydispersivity of colloidal samples. An additional thermocryostat allows to study systems as a function of temperature

The main components of the spectrometer are:

  • a Cobolt FlamencoTM 660nm DPSS Laser by Hubner Photonics;
  • a sample stage with an high-precision goniometer and decalin bath for index matching;
  • a double Avalanche Photon Detector (APD) by Excelitas technologies;
  • a Julabo CF31 high-precision thermocryostat.

The measure requires colloidal samples in compatible cuvettes.
-57°C<T<250°C to avoid the degradation of the decalin

Laser wavelength660 nm
Max Laser Power300 mW
Beam diameter0.7 mm
Laser cooling mechanismPassive heatsink
Temperature range1°C – 90°C
Scattering angle range8° – 153°
Minimum sampling time12.5 ns
Dark counts<500 cts
Radius of gyration5 nm – 5 µm
The Dynamic Light Scattering spectrometer
by LS Instruments
(photo credit: SDSClab@UniTN)

High-temperature photon correlation setup

Last born in our laboratory, this setup is designed exploit an high-temperature furnace to carry out PCI experiment on glasses close to the glass transition temperature and supercooled liquds.

The main components of the setup are:

  • a Cobolt SambaTM 532nm DPSS Laser by Hubner Photonics;
  • a custom optical furnace driven by a Eurotherm 3504 controller;
  • a Hamamatsu ORCA Flash 4.0 v3 CMOS camera.

The sample size is limited by the furnace dimension (maximum diameter: 20 mm )

Laser wavelength532 nm
Max Laser Power300 mW
Beam diameter0.7 mm
Laser cooling mechanismPassive heatsink
Furnace aperture24 mm
Temperature range13°C – 1000°C
Detector dimensions2048×2048 px2
Pixel size6.5 µm
Dark current0.06 e/px/s
FPS (frame rate)0.1 Hz-100 kHz

This is a work in progress setup…

We are planning to extend our time domain to catch also the fast dynamics…

Stay tuned!