A Laser Beam-Heated Miniature Oven for Matrix Isolation Raman Studies

Abstract

High-temperature Knudsen cells of various designs have been used by a number of investigators to measure the matrix-isolation vibrational spectra of inorganic salts. Recently we have initiated a matrix-isolation laser Raman study of inorganic and coordination compounds. This communication reports the design of a novel miniature oven which is heated by a laser beam to vaporize small quantities of solid compounds. The necessity for such a miniature oven arose when we tried to adapt the Cryogenic Technology Inc. model 21 closed cycle helium refrigerator to our Spex model 1430 sample illuminater. Because the latter is also used for ordinary Raman measurements, we planned to minimize its modification so that the matrix-isolation set-up can be converted easily to the normal configuration. The Spex illuminator is equipped with a high aperture Angenieux lens (f/0.95) with a focal length of 25 mm. However, the usable working distance between the lens and the focal plane is only 16 mm. That necessitated the design of a special Pyrex glass vacuum shroud as shown in Fig. 1 (part 1). This shroud is attached to an aluminum sleeve (part 2) which is attached to the refrigerator (part 3). A gas inlet and an electrical feed-through are housed on the aluminum sleeve (not shown in Fig. 1).