Knowledge Bank

A newly-developped Fourier Transform spectrometer (FTS), based upon a wave-front division interferometer, has recently been connected to the VUV beamline DESIRS on the French synchrotron facility SOLEIL. This instrument, unique in the world, using the pseudo-white coherent background continuum of an undulator, allows to perform ultra-high resolution absorption spectroscopy in the 140 - 40 nm spectral range}}, pp. 447-450 (2007).}, with a theoretical resolving power reaching 1000,000 over the full range. With the intrinsic multiplex capability of FTS over a wide spectral range (typically 5 % of the central wavelength) it should be a unique tool for the study of high lying electronic states of small diluted matter samples, in particular of atmospheric and astrophysical interest. As a first application and performance test of this new spectrometer, we have re-investigated at ultra-high resolving power ($\approx$ 700,000) the VUV absorption spectrum of Ne, Ar, Kr and Xe rare gases involving Rydberg series in the spectral range \mbox{[54-104] nm}, using a windowless room-temperature absorption cell. The comparison of our first results with previous data for these rare gases}, 10 (1988).}}, 9 (1970).}}, 1185 (1973).}}. 33 (2004).} led to the identification of several new transitions between the ground state and the five Rydberg {\it{ns}},{\it{ns'}} and {\it{nd}},{\it{nd'}} series and to a refined determination of the autoionization parameters of the {\it{ns'}} and {\it{nd'}} series.