Finnigan Corporation

William J Fies

John E Syka

Michael S Story

Ronald D Smith

John R Reeher

Paul E Kelley

George C Stafford, Jr

Mark E Bier

Dennis M Taylor

Walter E Reynolds

An external ion source assembly in which ion are formed in an ion volume by the interaction of energetic electrons and gas molecules. The effective energy of the electrons entering the ion volume is controlled by changing the voltage between the electron source (filament) and the ionization volume whereby ions having sufficient energy for ionizing atoms and molecules leave the electron source and enter the ionization volume only during an ionization period. The ion source assembly can be used both for electron impact ionization (EI) and for chemical ionization (CI).

Ion source assembly for an ion trap mass spectrometer and method

An unbalanced radio frequency voltage is supplied between two pairs of conductive rods of a quadrupole mass filter of a mass spectrometer system. Means are provided for d.c. voltage polarity reversal for monitoring positive and negative ions. The d.c. voltage is derived by rectification of the radio frequency voltage.

Quadrupole mass filter with unbalanced R.F. voltage

A quadrupole mass spectrometer in which a sample to be analyzed is ionized in a two or three dimensional electrostatic trapping field, and the ions in the range of the mass-to-charge ratios to be analyzed are excited at their characteristic frequencies of motion. The excited ions generate image currents which are detected and processed to provide a mass spectrum.

Fourtier transform quadrupole mass spectrometer and method

The method of operating a quadrupole ion trap in which the mass range of interest is analyzed in segments by trapping ions of successive mass ranges within the segments whereby the operating parameters for each segment may be selected to improve sensitivity and resolution.

Method of mass analyzing a sample over a wide mass range by use of a

Apparatus and method for programming the ion energy of ions being analyzed by a quadruple mass spectrometer where the axis potential applied to the quadruple rods is caused to vary in synchronism with a mass scan in order that the ions of each mass being analyzed may transit the quadruple with the most advantageous energy for proper analysis (that is, with substantially equal velocities) and the application of the ion scan voltage will not distort the fringing field at the entrance to the quadrupole.

Mass spectrometer system and method for control of ion energy for

A method of selecting a material for the construction of a multipole mass filter that is temperature stable or in other words, the R.sub.o parameter remains invariant with change in temperature. The coefficients of thermal expansion of the quadrupole rods and mounting structure are chosen so that a constant ratio of the two is provided which in turn is determined by the geometrical construction of the filter.

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Portola Valley, CA, United States of America

William J Fies