Formation of a gas beam by capillaries

The counting rate that can be obtained in electron spectrometry with gaseous species is an important figure to be considered. It depends on two competing factors, the target density in the source volume and the limitations set by the scattering losses of the electrons. Therefore, special attention must be given to the 

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The formation of molecular beams from nozzles of various shapes has been reported." Campargue ° recommends a short straight capillary with aratio of length to diameter equal to or greater than 2. In our homemade ion source, a 0.3-mm-diameter hole in a flat 1.0-mm-thick stainless-steel disk protected by a gas curtain has proven to be very robust and reliable in experiments with corona discharge ionization and electrospray. 

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