Francis william aston frs 1 september 20 november was an english chemist and physicist who won the nobel prize in chemistry for his discovery, by means of his mass spectrograph, of isotopes. Astons mass spectrograph the apparatus used by aston is shown in the figure the stream of positive ions from. His apparatus was the forerunner of aston s mass spectrograph and it is instructive to consider it wrst. Ionization chamber is used to ionize the gas whose mass or isotope is to be determined and positive ions are produced. A quadrupole mass spectrometer consists of an ionizer bombardment by electrons from a hot filament, an ion accelerator, and a mass filter consisting of four parallel metal rods arranged as in the figure above. Aston s original aston mass spectrograph complete with magnet. Thompsons later discovery of the electron also used one of the simplest mass spectrometers to bend the path of the cathode rays electrons and determine their charge to mass ratio. This device spread out the beam of positive ions into a mass spectrum of lines similar to the way light is separated into a spectrum. Because the device was set up like gustav kirchhoffs spectroscope, aston named it a mass spectrograph. The earliest forms of mass spectrometry go back to the observation of canal rays by goldstein in 1886 and again by wien in 1899. The first mass spectograph was designed by cambridge scientist f w aston. Bainbridge mass spectrograph engineering physics class. Lastly, other mass spectrograph geome tries that fall outside the freld of knowledge of the ion optics covered are discussed.
A velocity selector was used to produce a monovelocity ion beam and a transverse magnetic field was employed to discriminate between ions of different masses. Astons mass spectrograph mass spectrometry mechanics. Perspective dalton cavendish laboratory, university of. From there, we investigate the direction and energy focal lines of some mass spectrograph geometries, using the ion optics presented. Passing the beam between the poles of a large magnet then deflected the ions paths according to their mass.
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