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Description
We present a new experimental set-up devoted to the study of gas phase molecules and processes using broadband high spectral resolution rotational spectroscopy. A reactor chamber is equipped with radio receivers similar to those used by radio astronomers to search for molecular emission in space. The whole range of the Q (31.5-50GHz) and W bands (72-116.5GHz) is available for rotational spectroscopy observations. The receivers are equipped with 16x2.5GHz fast Fourier transform spectrometers with a spectral resolution of 38.14 kHz allowing the simultaneous observation of the complete Q band and one-third of the W band. The whole W band can be observed in three settings in which the Q band is always observed. Species such as CH_3_CN, OCS, and SO_2_ are detected, together with many of their isotopologues and vibrationally excited states, in very short observing times. The system permits automatic overnight observations, and integration times as long as 2.4x10^5^ seconds have been reached. The chamber is equipped with a radiofrequency source to produce cold plasmas, and with four ultraviolet lamps to study photochemical processes. Plasmas of CH_4_, N_2_, CH_3_CN, NH_3_, O_2_, and H_2_, among other species, have been generated and the molecular products easily identified by the rotational spectrum, and via mass spectrometry and optical spectroscopy. Finally, the rotational spectrum of the lowest energy conformer of CH_3_CH_2_NHCHO (N-ethylformamide), a molecule previously characterized in microwave rotational spectroscopy, has been measured up to 116.5GHz, allowing the accurate determination of its rotational and distortion constants and its search in space.
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