Design, Construction and Research Application of a Differential Electrochemical Mass Spectrometer (DEMS)Sean Ashton's doctoral thesis, which he finished at the Technical University in Munich, describes the challenge of constructing a Differential Electrochemical Mass Spectrometer instrument (DEMS). DEMS combines an electrochemical cell with mass spectrometry via a membrane interface, allowing gaseous and volatile electrochemical reaction species to be monitored online. The thesis carefully introduces the fuel cell electrocatalyst development concerns