PULSED FOURIER TRANSFORM MICROWAVE SPECTROSCOPY AT $140 GHz^{\ast}$
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Date
1984
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Ohio State University
Abstract
A pulsed microwave spectrometer operating in the vicinity of 140 GHz for the detection of rotational transitions in gaseous molecules is described. The spectrometer incorporates a tunable Fabry Perot cavity and a subharmonically pumped superheterodyne receiver for the detection of the molecular emission signals. Sufficient power at 140 GHz to excite the molecules is produced by pulse modulating a high efficiency frequency doubler at an intermediate frequency of 30 MHz with the cavity tuned to one of the modulation sidebands. The operation of the spectrometer is illustrated by the detection of emission signals from the $6(2,4)-6(1,5)$ transition of $SO_{2}$ gas. The generation of the electric dipole analog of NMR ``spin-echo'' signals by a $\frac{\pi}{2} - 2$ pulse sequence is also described.
Description
$^{\ast}$ Work supported by U.S. DOE under Contract No. DE-AC03-76SF00098.
Author Institution: Lawrence Berkeley Laboratory, University of California
Author Institution: Lawrence Berkeley Laboratory, University of California