Micromass Limited

Micromass UK Limited

Thomas Oliver Merren

Patrick James Turner

Raymond Clive Haines

James Speakman

Stuart Alan Jarvis

Robert Harold Bateman

John Brian Hoyes

Anthony James Gilbert

Jonathan C Cottrell

An ion detector ( ) for use in a time-of-flight mass spectrometer ( ) is disclosed. The ion detector ( ), which has an extended dynamic range, comprises at least one microchannel plate electron multiplier ( ) together with first and second collection electrodes ( ). The second collection electrode ( ) is arranged such that in receives more electrons per ion entering the ion detector ( ) than the first collection electrode ( ). In one embodiment the collection electrodes ( ) are formed in an array consisting of a larger plate-like collection electrode ( ) and a smaller plate-like collection electrode ( ). In an alternative embodiment a second microchannel plate electron multiplier is arranged between the first collection electrode ( ) and the second collection electrode ( ). In this embodiment the first collection electrode consists either of a grid electrode ( ) or more preferably of a wire electrode, and the second collection electrode consists of a plate-like electrode ( ).

Time of flight mass spectrometer and dual gain detector therefor

A plasma mass spectrometer comprises a plasma torch ( ) for generating ions from a sample introduced into a plasma ( ), a nozzle-skimmer interface ( ) for transmitting said ions into a first evacuated chamber ( ), ion guiding means ( ), an apertured diaphragm ( ) dividing said first evacuated chamber ( ) from a second evacuated chamber, and an ion mass-to-charge ratio analyzer in the second chamber for producing a mass spectrum. The ion guiding means comprises a multipole rod-set ( ), means for applying an AC voltage between rods in the set, and means ( ) for introducing into said ion guiding means an inert gas selected from the group comprising helium, neon, argon, krypton, xenon and nitrogen so that the partial pressure of said inert gas inside said rod-set is at least 10 torr. Interfering peaks in the spectrum, such as Ar , are thereby reduced.

Plasma mass spectrometer

The invention comprises a mass spectrometer,and a method of mass spectrometry that is especially useful for the measurement of the isotopic composition of hydrogen in the presence of a helium carrier gas. Interference to the accurate measurement of the small HD,peak at mass-to-charge ratio 3 by the much larger He,peak at mass-to-charge ratio 4 is reduced by provision of an energy filter,in the ion detector assembly used to collect HD,ions. This prevents ions of He,which have lost energy through scattering, etc giving rise to a signal from the HD,detector and distorting the deuterium hydrogen isotopic ratio measurement. Such a mass spectrometer,is typically used in conjunction with a continuous flow inlet system,based on an elemental analyzer that converts hydrogen present in a sample to gaseous hydrogen in a flow of helium carrier gas. Another embodiment of the invention provides a similar mass spectrometer useful for carbon or oxygen isotopic determinations in carbon dioxide gas.

Simultaneous detection isotopic ratio mass spectrometer

An ion detector (,) for use in a time-of-flight mass spectrometer (,) is disclosed. The ion detector (,), which has an extended dynamic range, comprises collection electrodes (,) of different surface areas. In one embodiment the collection electrodes (,) are formed in an array consisting of a larger plate-like collection electrode (,) and a smaller plate-like collection electrode (,). Microchannel multiplier plates (,) may be arranged in front of the collection electrodes (,). In an alternative embodiment the collection electrodes consist of a grid (,) or, more preferably, a wire electrode (,) disposed in front of a plate-like electrode (,).

Time of flight mass spectrometer and detector therefor

A plasma mass spectrometer comprises a plasma torch (,) for generating ions from a sample introduced into a plasma (,), a nozzle-skimmer interface (,) for transmitting said ions into a first evacuated chamber (,), ion guiding means (,), an apertured diaphragm (,) dividing said first evacuated chamber (,) from a second evacuated chamber, and an ion mass-to-charge ratio analyzer in the second chamber for producing a mass spectrum. The ion guiding means comprises a multipole rod-set (,), means for applying an AC voltage between rods in the set, and means (,) for introducing into said ion guiding means an inert gas selected from the group comprising helium, neon, argon, krypton, xenon and nitrogen so that the partial pressure of said inert gas inside said rod-set is at least 10,torr. Interfering peaks in the spectrum, such as Ar, are thereby reduced.

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Hale, United Kingdom

Thomas Oliver Merren