COMPACT HOT-NOZZLE FOURIER-TRANSFORM MICROWAVE SPECTROMETER

A newly constructed pulsed nozzle, Fourier-transform microwave spectro meter utilizes a Fabry-Perot cavity consisting of spherical resonators having diameters of only 10 cm. Tests of this very compact-cavity sys tem show that its sensitivity is only slightly lower than that of a co mparably configured system of the Balle-Flygare design having resonato rs with diameters of 36 cm. With a volume 50 times smaller than in con ventional systems, the compact cavity also requires a much smaller vac uum chamber which can be pumped by a relatively small 6 in. diffusion pump. The system includes an integral ceramic nozzle which can be heat ed to temperatures above 1000 degrees C. Spectrometer characteristics have been demonstrated by means of experiments on OCS isotopomers in g round and excited vibrational states, ArOCS complexes, and chloroketen e, a reactive intermediate formed by pyrolysis of chloroacetylchloride . (C) 1995 American Institute of Physics.