A COMPACT HOT-NOZZLE FOURIER-TRANSFORM MICROWAVE SPECTROMETER

A newly constructed pulsed nozzle, Fourier‐transform microwave spectrometer utilizes a Fabry–Perot cavity consisting of spherical resonators having diameters of only 10 cm. Tests of this very compact‐cavity system show that its sensitivity is only slightly lower than that of a comparably configured system of the Balle–Flygare design having resonators with diameters of 36 cm. With a volume 50 times smaller than in conventional systems, the compact cavity also requires a much smaller vacuum chamber which can be pumped by a relatively small 6 in. diffusion pump. The system includes an integral ceramic nozzle which can be heated to temperatures above 1000 °C. Spectrometer characteristics have been demonstrated by means of experiments on OCS isotopomers in ground and excited vibrational states, ArOCS complexes, and chloroketene, a reactive intermediate formed by pyrolysis of chloroacetylchloride.

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