摘要:
A mass spectrometer and method of mass spectrometry wherein charged particles in a beam undergo multiple changes of direction. A detection arrangement detects a first portion of the charged particle beam, and provides a first output based upon the intensity of the detected first portion of the charged particle beam. The detection arrangement detects a second portion of the charged particle beam that has traveled a greater path length through the mass spectrometer than the first portion of the charged particle beam, and provides a second output based upon the detected second portion of the charged particle beam. A controller adjusts the parameters of the charged particle beam and/or the detection arrangement, based upon the first output of the detection arrangement, so as to adjust the second output of the detection arrangement.
摘要:
An electrostatic trap such as an orbitrap is disclosed, with an electrode structure. An electrostatic trapping field of the form U′ (r, Φ, z) is generated to trap ions within the trap so that they undergo isochronous oscillations. The trapping field U′(r, Φ, z) is the result of a perturbation W to an ideal field U(r, Φ, z) which, for example, is hypologarithmic in the case of an orbitrap. The perturbation W may be introduced in various ways, such as by distorting the geometry of the trap so that it no longer follows an equipotential of the ideal field U(r, Φ, z), or by adding a distortion field (either electric or magnetic). The magnitude of the perturbation is such that at least some of the trapped ions have an absolute phase spread of more than zero but less than 2 π radians over an ion detection period Tm.
摘要:
Embodiments of the invention provide a detection apparatus for detecting charged particles having a charged particle detector for receiving and detecting either incoming charged particles or secondary charged particles generated from the incoming charged particles, a photon generator for generating photons in response to receiving at least some of the same incoming charged particles or secondary charged particles generated from the incoming charged particles as are received and detected by the charged particle detector, and a photon detector for detecting photons generated by the photon generator.
摘要:
An ion transfer arrangement for transporting ions between higher and lower pressure regions of the mass spectrometer comprises an ion transfer conduit 60. The conduit 60 has an inlet opening towards a relatively high pressure chamber 40 and an outlet 70 opening towards a relatively low pressure chamber. The conduit 60 also has at least one side wall surrounding an ion transfer channel 115. The side wall includes a plurality of apertures 140 formed in the longitudinal direction of the side wall so as to permit a flow of gas from within the ion transfer channel 115 to a lower pressure region outside of the side wall of the conduit 60.
摘要:
The invention provides a data acquisition system and method for detecting ions in a mass spectrometer, comprising: a detection system for detecting ions comprising two or more detectors for outputting two or more detection signals in separate channels in response to ions arriving at the detection system; and a data processing system for receiving and processing the detection signals in separate channels of the data processing system and for merging the processed detection signals to construct a mass spectrum; wherein the processing in separate channels comprises removing noise from the detection signals by applying a threshold to the detection signals. The detection signals are preferably produced in response to the same ions, the signals being shifted in time relative to each other. The invention is suitable for a TOF mass spectrometer.
摘要:
A method of selecting ions of interest from a beam of ions using an analyser, the method comprising: (i) providing an analyser comprising two opposing ion mirrors each mirror comprising inner and outer field-defining electrode systems elongated along an analyser axis z, each system comprising one or more electrodes, the outer system surrounding the inner; (ii) causing the beam of ions to fly through the analyser along a main flight path in the presence of an analyser field so as to undergo within the analyser at least one full oscillation in the direction of the analyser axis whilst orbiting about or oscillating between one or more electrodes of the inner field defining electrode system; (iii) providing one or more sets of electrodes adjacent the main flight path; (iv) constraining the arcuate divergence from the main flight path of ions of interest by applying one set of voltages to one or more of the sets of electrodes adjacent the main flight path when the ions of interest are in the vicinity of at least one of said one or more sets of electrodes adjacent the main flight path and applying one or more different sets of voltages to the said one or more sets of electrodes adjacent the main flight path when the ions of interest are not in the vicinity of at least one of said one or more sets of electrodes adjacent the main flight path; and: (v) ejecting the ions of interest from the analyser. Also provided is a charged particle analyser comprising the two opposing ion mirrors comprising inner and outer field-defining electrode systems elongated along an analyser axis z, and at least one arcuate focusing lens for constraining the arcuate divergence of a beam of charged particles within the analyser whilst the beam orbits around the axis z, the analyser further comprising a disc having two faces at least partly spanning the space between the inner and outer field defining electrode systems and lying in a plane perpendicular to the axis z, the disc having resistive coating upon both faces.
摘要:
The present invention provides a method of reflecting ions in a multireflection time of flight mass spectrometer comprising providing an ion mirror having a plurality of electrodes, the ion mirror having a cross section with a first, minor axis (Y) and a second, major axis (X) each perpendicular to a longitudinal axis (Z) of the ion mirror which lies generally in the direction of time of flight separation of the ions in the mirror; guiding ions towards the ion mirror; applying a voltage to the electrodes so as to create an electric field which: (a) causes the mean trajectory of the ions to intersect a plane of symmetry of the ion mirror which contains the longitudinal (Z) and major axes (X) of the mirror; (b) causes the ions to reflect in the ion mirror; and (c) causes the ions to exit the ion mirror in a direction such that the mean trajectory of ions passing through the ion mirror has a component of movement in a direction (Y) perpendicular to and diverging from the said plane of symmetry thereof.
摘要:
A method of operating a gas-filled collision cell in a mass spectrometer is provided. The collision cell has a longitudinal axis. Ions are caused to enter the collision cell. A trapping field is generated within the collision cell so as to trap the ions within a trapping volume of the collision cell, the trapping volume being defined by the trapping field and extending along the longitudinal axis. Trapped ions are processed in the collision cell and a DC potential gradient is provided, using an electrode arrangement, resulting in a non-zero electric field at all points along the axial length of the trapping volume so as to cause processed ions to exit the collision cell. The electric field along the axial length of the trapping volume has a standard deviation that is no greater than its mean value.
摘要:
An ion transfer tube for a mass spectrometer comprises a tube member having an inlet end and an outlet end; and at least one bore extending through the tube member from the inlet end to the outlet end, the at least one bore having a non-circular cross section. A method of forming an ion transfer tube comprises the steps of providing a tube member having a length and an internal bore, the internal bore having a wall of circular cross section; and etching or eroding portions of the tube member adjacent to the wall so as to form an enlarged bore having a non-circular cross section.
摘要:
Methods and analysers useful for time of flight mass spectrometry are provided. A method of separating charged particles comprises the steps of: providing an analyser comprising two opposing mirrors each mirror comprising inner and outer field-defining electrode systems elongated along an axis z, the outer system surrounding the inner and defining therebetween an analyser volume, the mirrors creating an electrical field within the analyser volume comprising opposing electrical fields along z, the strength along z of the electrical field being a minimum at a plane z=0; causing a beam of charged particles to fly through the analyser, orbiting around the z axis within the analyser volume, reflecting from one mirror to the other at least once thereby defining a maximum turning point within a mirror; the strength along z of the electrical field at the maximum turning point being X and the absolute strength along z of the electrical field being less than |X|/2 for not more than ⅔ of the distance along z between the plane z=0 and the maximum turning point in each mirror; separating the charged particles according to their flight times; and ejecting at least some of the charged particles having a plurality of m/z from the analyser or detecting the at least some of charged particles having a plurality of m/z, the ejecting or detecting being performed after the particles have undergone the same number of orbits around the axis z.