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GARRY S. GRUBBS II, CHRISTOPHER T. DEWBERRY AND STEPHEN A. COOKE, Department of Chemistry, The University of North Texas, P. O. Box 305070, Denton, Texas, 76203, U.S.A.
We will present the design and operation of a simple Balle-Flygare-type spectrometer operable between 75 and 110 GHz (W-band). W-band frequencies are generated through the use of active multiplier chains. The circuit uses single side-band modulation with an IF of 180 MHz. The Fabry-Perót cavity consists of two opposing spherically concave mirrors, 70 mm in diameter with a 250 mm radius of curvature. The mirrors have been machined from copper and diamond polished to achieve a maximum surface defect of 135 nm. A solenoid valve admits pulses of gas into the cavity which is housed in a small vacuum chamber maintained at a resting pressure of <10-7 bar using a turbomolecular pump. The instruments use and sensitivity will be demonstrated using some simple gas phase species.