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Optistat CF2

Oxford Instruments

Optistat CF2 Helium cryostat 4 K, sample in exchange gas

• Wide temperature range
• Quick sample change in less than 5 minutes via top-loading sample probe
• Superb optical access for measurements requiring light collection
• Optimised clear beam throughput (15 mm diameter aperture) allows a large illumination area for measurements involving the detection of low intensity light
• The most economical use of cryogens on the market: less than 0.55 L/hr at 4.2 K using a Low Loss Transfer tube
• Versatile: wide range of sample holders/rods including liquid cuvette for liquid samples and precise height adjust/rotate sample rod
• Compact size allowing easy integration into commercial spectrometers
• Electrical measurements via 10-pin electrical feed wire to heat exchanger and/or wired on coax connectors
• Can be operated in pull mode (using a gas flow pump to pull the helium from a storage dewar to the sample space) or push mode (by pressurising the storage dewar)
• Two models to choose from: static or dynamic exchange gas
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  • Specifications
  • System Components/Options
  • Optional items
  • Sample environment options
  • Window options
  • Pump options
  • Transfer lines
  • Applications
  • PDFs


OptistatCF2 static used in ´pull´ mode

OptistatCF2 static used in ´push´ mode

OptistatCF2 dynamic in ´pull´ mode

OptistatCF2 dynamic used in ´push´ mode

Temperature range

2.3 - 500 K*

4.2 - 500 K*

2.3 - 500 K*
1.6 - 500 K* in single shot

4.2 - 500 K*

Temperature stability

± 0.1 K (measured over 10 min period)

Maximum sample space

20 mm diameter

Sample holder dimension

19 mm wide x 30 mm long (optical sample holder version has a 15 mm aperture)

Cool down from ambient to 4.2 K (mins)


• OptistatCF helium cryostat
• Sample holder and rod
• Up to five sets of windows. (four radial; one axial). Each set includes three windows (inner, radiation shield and outer case windows)
• Cryogen transfer tube
Mercury iTC temperature controller
• High vacuum pumping system
• Helium dewar
• Gas flow pump
• Gas flow controller
• Automated transfer tube allowing fully automated control across the entire temperature range
• Wiring and electrical connections to the sample
• Simple height adjust and rotate sample rod: provides sliding adjustment with locking screws to hold a fixed position. The range of vertical motion is 32 mm. Positioning accuracy is 0.5 mm (height) and 1 degree (rotation).
• Precise height adjust and rotate sample rod provides height adjust and with a resolution of 10 µm and a goniometer for setting the rotation angle with a resolution of 12 minutes.
• Liquid cuvette for liquid samples
• OptistatCF with static exchange gas: the circulating cryogen does not come into contact with the sample. The heat exchanger is in good thermal contact with the sample space which contains an independent exchange gas (usually helium). The sample is cooled by conduction through the exchange gas.
• OptistatCF with dynamic exchange gas: temperature stabilised cryogen flows into the exchange gas space cooling the sample directly. This version is recommended for large low conductivity samples or when large heat loads are applied to the sample. Also the cryostat can be used in single shot mode. The sample space is then filled with helium and pumped enabling a base temperature of 1.6 K for approximately 20 minutes (using an EPS 40 pump).
• A wide range of window materials can be fitted to the OptistatCF to meet specific spectroscopy applications
• Special windows with non-parallel faces and anti-reflection coatings are available
• Additional or replacement window flanges available via the Oxford Instruments Direct - Cryospares® on-line catalogue
• A simple oil-free vane pump GF4 is supplied for operation to 3.4 K
• Lower temperatures to 2.3 K require an EPS40 single stage rotary pump; this also extends the base temperature for the dynamic exchange gas version to 1.6 K
• Oxford Instruments Low Loss Transfer tubes (LLT) use the cold gas exiting the cryostat to cool the shields surrounding the incoming liquid within the transfer tube. As a result, the consumption of our cryostats is the lowest on the market, dramatically reducing your running costs.
• We can also offer an extra flexible transfer tube for those with restricted space in their labs. Please note that as this does not use the gas cooled mechanism, helium consumption will be higher than for the LLT range. However it will be well suited to those who need a lightweight and more flexible transfer tube.
• An auto needle valve can be fitted to the LLT which allows the temperature controller to optimise the helium flow rate

UV/Visible spectroscopy: Experiments at low temperatures reveal the interaction between the electronic energy levels and vibrational modes in solids.

Infrared spectroscopy: Low temperature IR spectroscopy is used to measure changes in interatomic vibrational modes as well as other phenomena such as the energy gap in a superconductor below its transition temperature.

Raman spectroscopy: Lower temperatures result in narrower lines associated with the observed Raman excitations.

Photoluminescence: At low temperatures, spectral features are sharper and more intense, thereby increasing the amount of information available.

Case study: Dr Handong Sun from the Institute of Photonics  (Glasgow) is using the OptistatCF2 to perform experiments of photoluminescence (PL) and PL excitation (PLE) spectra from 5 K to 300 K on dilute nitrides of III-V semiconductors and related nanostructures. The aim is to elucidate the electronic states and PL mechanisms in this novel material system.