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Russian Vacuum Electronics (reference materals).
Ed. M.I. Petelin

MOLECULAR SPECTROSCOPY
WITH PHASE-LOCKED MILLIMETER AND SUBMILLIMETER-WAVE BWOS

A.Krupmov, G. Golubiatnikov, M. Tretyakov
trt@appl.sci-nnov.ru

BWOs phase-locked to harmonics of lower frequency synthesizers have provided a dramatic break-through in the high-resolution molecular spectroscopy at up-to-Terahertz frequencies: the digitally controlled continuous frequency sweep within up-to-100 GHz band is combined with a high signal-to-noise ratio.
Pressure and temperature line broadening are measured with a very high precision. Phase-locked narrow-spectrum milliwatt-power BWOs proved to be well sufficient for observing 20-100 Hz wide Lamb-dips of molecular spectral lines; the central frequency being measured with ±500Hz precision.
The digital frequency sweep with 0.3 Hz step and 200 nanoseconds switching time gives an opportunity to adjust the resonator spectroscopy for on-line measurements of atmospheric lines.


Main components of MM-SubMM spectrometers – pocketsized BWOs, waveguide frequency multiplier and quasi-optical multiplier-mixer
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Spectrum of open laboratory atmosphere obtained by resonator spectrometer and its comparison with theoretical calculations