04121099 is referenced by 30 patents and cites 4 patents.

A method and apparatus for focussing and declustering trace ions travelling from a gas through an orifice into a vacuum chamber and to a mass analyzer in the vacuum chamber. Advantage is taken of the free jet expansion of the gas into the vacuum chamber by applying an electric focussing field in a specific region of the free jet. The region is selected sufficiently close to the orifice that the gas density limits the kinetic energy spread which the ions can acquire under the applied field, typically to 2 ev or less, while the early focussing increases the available ion signal. Declustering can be collision induced in the region by providing a field in the region sufficient to impart an internal energy of between 0.1 and 1.5 ev to ions in the region. The kinetic energy which the ions can acquire under the applied field is still limited by the density of the gas in the free jet, so that the kinetic energy spread which the ions can acquire is still limited. Preferably the focussing and declustering fields are produced by a single conical tapered lens element located at distance X.sub.l from the orifice, where ##EQU1## and D is the orifice diameter, for atmospheric pressure and room temperature source conditions. The electric field between the lens element and the mass spectrometer is then controlled to limit the energy spread imparted to the ions in their travel from the lens elements to the mass spectrometer.

Title
Method and apparatus for focussing and declustering trace ions
Application Number
555202
Publication Number
4121099
Application Date
April 25, 1977
Publication Date
October 17, 1978
Inventor
Janette A Buckley
Willowdale
CA
Neil M Reid
Thornhill
CA
John Barry French
Thornhill
CA
Agent
Rogers Bereskin & Parr
Assignee
The Governing Council of the University of Toronto
CA
IPC
B01D 59/44
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