DEVELOPMENT OF A PULSED MOLECULAR BEAAM FOURIER TRANSFORM MICROWAVE SPECTROMETER IN THE 26 TO 40 GHZ REGION

Author Institution: Laboratoire de Physique Mol\'eculaire et Applications, B\^{a}t 350, Universite de Paris-Sud; Institut f\""{u}r Physikalische Chemie, der Universitat KielAfter pulsed molecular beam (MB) Fourier transform microwave (FTMW) spectroscopy has become a widely used technique for the investigation of stable molecules, van der waals clusters, free radicals, and recently also ions. We felts it worth while to extend the frequency range covered by this method to a higher limit. In order to minimize the use of expensive microwave equipment in the 26-40 GHz range, the polarizing pulses are produced by a microwave synthesizer in the range from 13 to 20 GHz with subsequent frequency doubling. For down conversion of the free induction decay a subharmonic mixer is used. As in our MB-MWFT spectrometers below 26 GHz the molecular beam is pulsed through one of the mirrors of the Fabry-Perot cavity. In this way also at high frequencies very narrow lines and a high resolution is achieved. Technical details of the apparatus and some spectroscopic applications will be presented