Time-of-flight mass-spectrometer with gasphase ion source, with high sensitivity and large dynamic range
AssigneesThorald Bergmann, Eva Martina Bergmann
InventorThorald Bergmann
Life of this patent
Estimating the term…
Abstract
A high particle density in the extraction volume of a gasphase ion source and simultaneously a very low particle density in the driftspace of the time-of-flight mass-spectrometer are necessary for high sensitivity and a large dynamic range of the mass-spectrometer signal output. This can be achieved by separating the time-of-flight mass-spectrometer into two or more regions of different pressure, connecting the different regions by gas flow restrictions. A maximum particle density in the extraction volume and simultaneously a minimal particle density in drift space can be achieved by integrating the gas flow restrictions(3,6) directly into the electrodes(1,2) of the ion source.
Claims21
A time-of-flight mass-spectrometer,
- said time-of-flight mass-spectrometer being subdivided into two or more regions of different pressures p1, p2, p3, . . . ,
- at least two of said regions of different pressures being connected via flow restrictions(3,6),
- with gasphase ion source,
- having a number of electrodes(1,2,4,5) for producing electrical fields,
- in which is defined a region of space called extraction volume (11), said region containing ions at start-time of mass-analysis, the mass of said ions being determined by measuring their time-of-flight,
- in which a further region of space is defined,
- a) that contains the extraction volume(11),
- b) in which the electrical field is everywhere nonzero and directed such as to accelerate, (not decelerate) the ions or electrons,
- c) in which the ions or electrons to be detected are accelerated in an uninterrupted phase of time, immediately following the start-time of mass analysis, at least to some fraction of the final drift velocity in the time-of-flight mass spectrometer,
- characterized by one or several electrodes(1,2,4,5), said electrodes simultaneously
- having integrated gas flow restrictions(3,6)
- being able to influence the electrical field in one or both of the previously defined regions of space.
Method of mounting an electrode(1,2) onto a wall(31) of a vacuum housing,
- said electrode forming a boundary between regions of different gas pressure,
- said electrode having a potential different from the potential of the vacuum housing,
- characterized by
- said wall(31) of the housing and said electrode(1,2) partially overlapping each other,
- a gap remaining between said wall(31) of the vacuum housing and said electrodes(1,2), and said gap being determined by a piece of insulator(32),
- said gap being so small, such that the gas conductivity of said gap is smaller than the pumping capacity of the pump which pumps the region of lower residual gas pressure.
Dependencies are inferred from the claim text.