Química Nova

p. 315-319,May/June.A TIME-OF-FLIGHT MASS SPECTROMETER FOR HIGH ENERGY (0.5 – 1.0 KEV) ELECTRON IONIZATION OF GASES. A simple and inexpensive time-of-flight mass spectrometer, dedicated to the study of gas-phase ionization processes induced by high energy electrons (0.5 – 3.0 keV), is described. The spectrometer design is based on the Wiley-McLaren principle, with a total length of about 18 cm. As a demonstration of the performance of the apparatus, mass spectra for Ar, CH4, CO2, and SF6, obtained at 1 keV electron energy, are presented