Scheme for collinear ionization in supersonic jet/multiphoton ionization/time-of-flight mass spectrometry Original Research Article

A new ionization scheme is proposed, in which the analyte molecule, ejected from a nozzle into a throat, is expanded from a repeller into a vacuum and immediately ionized and accelerated downstream for time-of-flight mass analysis. The ionization efficiency is improved by a factor of 50, which is in reasonably good agreement with the predicted value of 25, calculated from the distance between the nozzle and the ionization region for the cases of collinear (10 mm) and non-collinear (perpendicular) (50 mm) configurations. This approach has the unique capability for ‘temperature tuning’ of the analyte molecule by changing the position of the ionization region, thus permitting control of the spectral linewidth and, thereby, application of supersonic jet spectrometry to samples of unknown composition.