In some cases, it is essential to control the environment to which the sample is exposed. Thus, catalysts may require heating and evacuation or be exposed to a vapour. The Model H-4 cell encloses the sample behind a thin borosilicate glass window. The cavity containing the sample can be evacuated or filled with gas through the standard ¹/16" stainless steel micro tubing familiar to all chromatography users and, of course, the cell body can be heated. In this case, we are restricted to 180°C. The Model H-5 cell enables users to study liquids or viscous melts. The standard sample container is a shortened NMR tube but an adaptor is provided to enable users to study samples in melting point tubes or in sample vials. To control the heating process and to monitor the temperature of all the Ventacon Hot Cells, we recommend that users purchase the Series D Universal Power Supply or the new DV hot cell supply. These units provide a stabilized DC supply at ~24v. Temperature sensing and control is achieved using a CAL differential proportional controller. HIGHER TEMPERATURES It is feasible to fit a filter into the optical path of the Raman spectrometer to restrict the effect of the black body emission. The filter blocks radiation at shifts greater than 2000cm-1 enabling users to record spectra at temperatures up to 300°C or even a little higher. Remember – the filter attenuates the black body radiation and the Raman bands as well so bands at higher shifts do not appear. Ventacon can supply each of the cells listed above – H-1, H-2 and H-4, in an extended range version – models H-1 HT, H-2 HT, H-4 HT and H-5 HT. All are suitable for both the Perkin Elmer 1700 and 2000 Series instruments, but not those from other manufacturers. We can supply a filter and a mount for the 1700 instruments or users can fit the filter themselves but Perkin Elmer must supply and fit a filter to the 2000 instrument. This can be done by a Perkin Elmer service engineer.
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