All Ventacon cells operate inside the sealed sample compartment and are therefore based on a different system - the 'transfer gas' design.

Transfer gas cells use a liquid refrigerant to provide cooling; transferring the thermal energy from the specimen to the refrigerant by convection in the gas that surrounds the sample.

The sample tube 'C' in the diagram is cooled by the refrigerant and causes the gas inside it to flow down the inside surface. As it warms, it rises up the centre and then flows downwards again as before. In doing so, the sample is cooled by the gas flowing over it. If left alone the sample will cool to a temperature a little above that of the refrigerant. If electrical heating to the sample holder is provided, the temperature of the specimen can be raised and controlled. Samples are held in probes, which are suspended in the centre of Tube C.

Six probes are available - two simple ones suitable for holding solids and two for liquids (enclosed in open or closed glass tubes) and two equivalent but electrically heated versions. The simple probes include a built in thermocouple temperature sensor. Ventacon will provide a digital thermometer so that the sample temperature can be measured, but this can only be supplied for C-15 or C-16 probes. Models C-11 and C-12 include copper constantan thermocouples # and are compatible with the Ventacon Series DII Universal Power Supplies.

The heated probes also incorporate a thermocouple #, again compatible with the Ventacon Series DII Universal Power Supply. The latter provides the electrical energy to alter and control the temperature of the samples.

The Ventacon Series C Cold Cell is made of especially selected borosilicate glass, the 'central' tube being placed very close to the side wall to optimise the optical performance as a Raman cell. Over the temperature range from Room Temperature to 150ºC we recommend the use of ice/water, ice/salt, solid CO₂/acetone or liquid nitrogen as coolants.

The Ventacon C-1 Cold Cell suitable for the Perkin Elmer Raman Station 400 resembles the C-1 Cold Cell in its Thermo Nicolet configuration (see top picture of previous page).

# Ventacon is changing to miniature Pt resistance sensors. These are compatible with the Ventacon Series D Universal Power Supplies and provide slightly better performance than do thermocouples.

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