University of Toronto

Sciex Inc.

Janette A Buckley

John Barry French

Neil M Reid

A multiple stage cryogenic vacuum pump is disclosed for transferring matter or species between a gas and a vacuum chamber. The vacuum chamber has an orifice through which the matter or species moves and through which some of the gas leaks into the chamber. The chamber also has an interior surface which is spaced from the path of movement of the matter or species and encircles such path, and an internal divider extending to a position adjacent the interior surface and dividing the chamber into a first region adjacent the orifice and a second region downstream from the first region, with the interior surface extending in both regions. The surface is cooled by a single refrigerating device to below the condensation temperature of the gas, to produce a pressure below atmospheric in the first region and a lower pressure in the second region. The divider contains an aperture through which the matter or species travels and may itself be cooled to precool gas contacting it. The matter or species may be ions or may be a strip of material to be treated. In the latter case the gas which is cryopumped can be warmed and flowed countercurrent to the strip to precondition the strip prior to its entry into the vacuum chamber.

Multiple stage cryogenic pump and method of pumping

Apparatus for analyzing trace components contained in a sample gas. The sample gas is directed into a reaction chamber and ionized. The resultant trace ions are drifted by an electric field, out of the sample gas, through an inert gas curtain and then through an orifice into a vacuum chamber where they are focused and analyzed. The curtain gas flow may be greater than the flow through the orifice, in which case the gas curtain acts as an ion window which is transparent to ions but blocks sample gas flow into the vacuum chamber. Alternatively, the curtain gas flow may be controlled to admit a desired flow of sample gas through the curtain into the vacuum chamber, in which case the gas curtain acts as a window for ions and as an infinitely variable orifice for the sample gas. Preferably the curtain gas is cryopumpable and is cryopumped by cooling the interior surface of the vaccum chamber.

Method and apparatus for analyzing trace components using a gas curtain

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.

Method and apparatus for focussing and declustering trace ions

A method of analyzing a trace gas, in which the trace gas is transported in a carrier gas stream into a reaction chamber where the trace gas is ionized. The carrier gas includes or is a reagent gas which is ionized in the reaction chamber and the ions of which in turn form trace gas ions. The carrier gas, which is cryopumpable, is then injected with the trace gas ions into a vacuum chamber, the walls of which are cooled to cryopump the reagent gas and thus strip it away from the trace gas ions. The trace gas ions are focussed into an analyzer and analyzed.

Growing community of inventors

Willowdale, Canada

Janette A Buckley