A gas inlet system for quantitative mass spectrometry

摘要: A gas inlet system for quantitative mass spectrometry is described. The principle to make the pass through ion source using tubing terminating close source. With molecular flow conditions in a directed, reasonably collimated beam achieved giving rise local pressure increase This due molecules that have not interacted with chamber walls, and can easily be obtained each species of interest by taking signal differences or lock-in techniques if shutter/chopper positioned between sample traditional plagues spectrometry, namely background gases wall gas-exchange effects are thus eliminated. For stable this offers essentially same advantages as inlet, but at much lower cost complexity requiring smaller samples analysis. example, no differential pumping required. The properties performance sampling analysed theoretically demonstrated experiments. Good agreement theory experiment. It shown theoretically, verified experimentally, ratio R, source, directed beam, average spectrometer (MS) varies R ≈ S M12 where speed M number. As specific example it how water vapour content correctly measured even presence high MS vacuum chamber. also device used simple tool measure speeds systems.