DOUBLE MODULATION TECHNIQUE IN PULSED JET EXPERIMENTS: MOLECULAR VAN DER WAALS COMPLEXES

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 Title: DOUBLE MODULATION TECHNIQUE IN PULSED JET EXPERIMENTS: MOLECULAR VAN DER WAALS COMPLEXES Creators: Pak, I.; Hepp, M.; Roth, D. A.; Winnewisser, G. Issue Date: 1996 Publisher: Ohio State University Abstract: A double modulation technique was used to achieve higher sensitivity in absorption measurements with a pulsed supersonic jet. The wavelength of a lead-salt diode laser was modulated at a frequency of 10 KHz and detected at twice the frequency by a lock-in amplifier, reducing significantly the influence of the low frequency excess laser noise. The output of this lock-in amplifier was measured by a boxcar integrator, driven at 80 Hz, the frequency of the pulsed jet. The same technique was applied to the jet absorption measurements in the millimeter wave region using mm-wave synthesizers as radiation sources. The recorded spectra of Ar-$CH_{4}$, Kr-$CH_{4}$ and Ar-CO molecular van der Waals complexes are presented in order to show the improved sensitivity of the tunable diode laser and mm-wave spectrometers. Description: Author Institution: I. Physikalisches Institut, Universit\""{a}t zu K\""{o}ln URI: http://hdl.handle.net/1811/13433 Other Identifiers: 1996-ME-09