Nitrogen cryostat with integrated reservoir, sample in exchange gas: OptistatDN.

Nitrogen cryostat ideal for experiments requiring 77K base temperature, high sample throughput and for samples which are difficult to cool by conduction. Its small footprint is ideal in laboratory where space is limited. It doesn’t required any external dewar or transfer tube.

Wide temperature range: from 77 K to 500 K
Quick sample change in less than 5 minutes via top-loading sample probe
15 hours cryogen hold time before refills required providing the convenience of a full working day operation
Superb optical access (f/1) 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
Versatile: wide range of sample holders/rods including liquid cuvette for liquid samples and simple/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

Particularly suitable for low temperature absorption, fluorescence and photoluminescence spectroscopy.

Specifications
System components/options
Operation
Applications
Images

Layout and dimensions

OptistatDN liquid nitrogen (LN2) optical spectroscopy cryostat dimensions

Specifications

Maximum sample space available	20 mm diameter
Sample holder dimensions	19 mm wide x 30 mm long (Optical sample holder version has a 15 mm aperture)
Temperature range	77-500 K
Temperature stability	± 0.1 K (measured over 10 minute period)
Cooldown time from ambient to 77 K	20 minutes (25 minutes for 500 K option)
Liquid nitrogen capacity	1.2 litres
Hold time at 77 K	≥ 15 hours
Sample change time	5 minutes
Cryostat weight	5 kg

A typical system consists of:

OptistatDN nitrogen cryostat
Sample holder and rod
Up to five sets of windows. (four radial; one axial). Each set includes two windows (radiation shield and outer case windows)

New Mercury iTC temperature controller

High vacuum pumping system

Optional items:

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. Postioning 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

Windows

A wide range of window materials can be fitted to the OptistatDN 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

Sample holders/rods options

Adding to the OptistatDN versatility is the ability to fit several different sample rods and holders:

Standard sample rod: single sample holder with 10-pin electrical access
Simple height adjust and rotate sample rod: height adjust range 32 mm with positioning accuracy 0.5 mm, rotate adjust range 360° with positioning accuracy 1°
Precision height adjust and rotate sample rod: Height adjust range 30 mm with 10 µm resolution, rotate adjust range 360° with 12 minutes resolution
In addition to the sample positioning and 10-pin electrical access, both height adjust and rotate sample rods feature a double sample holder. For applications such as FTIR, the reference and sample can be measured without having to move the cryostat or exchange samples
A liquid cuvette sample holder enables liquid sample experiments
Additional or replacement sample rods are available via the Oxford Instruments Direct - Cryospares on-line catalogue

New OxSoft IDK instrument development kit software

With the new Oxsoft IDK you have new levels of control. You can design remote control and configuration programs and integrate your system into your preferred experiment control architecture.

See also the OptistatDN-V for this cryostat with sample in vacuum.

The OptistatDN cryostat cools samples using liquid nitrogen from an integral nitrogen reservoir. Liquid nitrogen, stored in the upper part of the cryostat, is gravity fed to a heat exchanger surrounding the sample tube. The sample is then cooled by conduction via a helium or nitrogen exchange gas in the sample space.

A vaccum case surrounds the nitrogen reservoir and heat exchanger. It needs to be pumped to high vacuum (lower than 10-4 mbar). An activated charcoal sorb is fitted to the nitrogen reservoir. This continously pumps the residual gases from the OVC to maintain good thermal isolation.

Changing the sample simply involves removing the sample rod maintaining overpressure of exchange gas , replacing the sample and inserying the rod back into the cryostat. There is no needs to break the insulating vacuum and warm the cryostat up. The resulting sample change times are very short, typically few minutes.

Temperature control is achieved by a combination of manual nitrogen flow control and power dissipated in an electrical heater, regulated using a temperature controller.

OptistatDN and DN-V liquid nitrogen (LN2) optical spectroscopy cryostat operating principle

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.

Gas absorption : We have developed a special cryostat in partnership with Quantachrome Instruments to fit their autosorb-iQ gas sorption analyzers. More application details here.

Case study:

Dr Ken Haenen and Prof Jean Manca (Limburg university, Diepenbeek - Belgium) use the OptistatDN in combination with a FTIR spectrometer to perform Fourier Transform Photoconductive Spectroscopy FTPS. FTPS is a highly sensitive photocurrent method for materials with low optical absorption such as conjugated polymer and CVD-diamond films, which are developed for novel electronic, and bio-electronic applications.