Advanced Undergraduate Laboratory

Department of Physics

University of Toronto

MASS: Mass Spectrometer

In this experiment students scatter electrons from atoms and molecules, measuring the ionization threshold and cross-section as a function of energy. Students learn how to operate a mass spectrometer and the vacuum system associated with it. There have been six Nobel Prize winners for work in the development of Mass Spectrometry, the most recent (Chemistry 2002) being for ionization methods for biological macromolecules.

Write-Up in PDF Format or Microsoft Word Format.

(The experiment is currently located in MP226; last major write-up revision: Feb. 2005.)

Additional resources:

• Wolfgang Lotz (1967) "An Empirical Formula for the Electron-Impact Ionization Cross-Section".
• Wetzel et al. (1987) "Absolute cross sections for electron-impact ionization of the rare-gas atoms".
• Vinodkumar et al. (2007) "Calculations of elastic, ionization and total cross sections for inert gases upon electron impact: threshold to 2 keV".
• Ionization Energies of the Elements from Wikipedia.
• NIST Electron-Impact Cross Section Database and Introduction.
• Afzal Chaudhry, Hans Kleinpoppen, "Analysis of Excitation and Ionization of Atoms and Molecules by Electron Impact", Springer (2011).
• Nagamitsu Yoshimura, "Vacuum Technology: Practice for Scientific Instruments", Springer (2008). See cracking patterns on page 240-241.

Zeynab Danesh, 3^rd year undergraduate, working with the Mass Spectrometer. In the foreground is Tak Sato, former technologist for the 3^rd and 4^th year laboratories.

Last updated on 18 October 2018