Micromass UK Limited

Leco Corporation

Anatoly Verenchikov

Mikhail Yavor

John Brian Hoyes

Keith George Richardson

Jason Lee Wildgoose

Improved multi-pass time-of-flight mass spectrometers MPTOF, either multi-reflecting (MR) or multi-turn (MT) TOF are proposed with elongated pulsed converters—either orthogonal accelerator or radially ejecting ion trap. The converteris displaced from the MPTOF s-surface of isochronous ion motion in the orthogonal Y-direction. Long ion packetsare pulsed deflected in the transverse Y-direction and brought onto said isochronous trajectory s-surface, this way bypassing said converter. Ion packets are isochronously focused in the drift Z-direction within or immediately after the accelerator, either by isochronous trans-axial lens/wedgeor Fresnel lens. The accelerator is improved by the ion beam confinement within an RF quadrupolar field or within spatially alternated DC quadrupolar field. The accelerator improves the duty cycle and/or space charge capacity of MPTOF by an order of magnitude.

Multi-pass mass spectrometer

Improved ion mirrors(FIG.) are proposed for multi-reflecting TOF MS and electrostatic traps. Minor and controlled variation by means of arranging a localized wedge field structureat the ion retarding region was found to produce major tilt of ion packets time fronts. Combining wedge reflecting fields with compensated deflectors is proposed for electrically controlled compensation of local and global misalignments, for improved ion injection and for reversing ion motion in the drift direction. Fine ion optical properties of methods and embodiments are verified in ion optical simulations.

Ion mirror for multi-reflecting mass spectrometers

Apparatus and method are proposed for the strong improvement of dynamic range (DR) of detectors and of data systems for time-of-flight mass spectrometers (TOF MS) with periodically repetitive signals. TOF separated ions are converted into secondary particles, primarily electrons, and the flow of secondary particles is controllably attenuated to sustain the data acquisition system in a counting mode above the electronic noise threshold. The acquisition time is split between at least two time segments, characterized by alternated transmission efficiency SE of secondary particles. Using strong electron suppression (SE«1) is employed for recording intense ion peak, while counting ions with either ADC, or TDC, or ADC with extracting peak centroids. A longer time segment employs an efficient electron transfer (SE=1) for detecting weak ion species. In another independent aspect, an ion-optical element is provided upstream of the ion detector and is configured to deflect, reflect or retard ions such that ions that have been scattered or fragmented in the time of flight region do not impact on the ion detector.

TOF MS detection system with improved dynamic range

Improved pulsed ion sources and pulsed converters are proposed for multi-pass time-of-flight mass spectrometer, either multi-reflecting (MR) or multi-turn (MT) TOF. A wedge electrostatic field () is arranged within a region of small ion energy for electronically controlled tilting of ion packets () time front. Tilt angle &#x3b3; of time front () is strongly amplified by a post-acceleration in a flat field (). Electrostatic deflector () downstream of the post-acceleration () allows denser folding of ion trajectories, whereas the injection mechanism allows for electronically adjustable mutual compensation of the time front tilt angle, i.e. &#x3b3;=0 for ion packet in location (), for curvature of ion packets, and for the angular energy dispersion. The arrangement helps bypassing accelerator () rims, adjusting ion packets inclination angles &#x3b1;and what is most important, compensating for mechanical misalignments of the optical components.

Accelerator for multi-pass mass spectrometers

Improved multi-pass time-of-flight mass spectrometers MPTOF, either multi-reflecting (MR) or multi-turn (MT) TOF are proposed with elongated pulsed converters&#x2014;either orthogonal accelerator or radially ejecting ion trap. The converteris displaced from the MPTOF s-surface of isochronous ion motion in the orthogonal Y-direction. Long ion packetsare pulsed deflected in the transverse Y-direction and brought onto said isochronous trajectory s-surface, this way bypassing said converter. Ion packets are isochronously focused in the drift Z-direction within or immediately after the accelerator, either by isochronous trans-axial lens/wedgeor Fresnel lens. The accelerator is improved by the ion beam confinement within an RF quadrupolar field or within spatially alternated DC quadrupolar field. The accelerator improves the duty cycle and/or space charge capacity of MPTOF by an order of magnitude.

A multi-pass time-of-flight mass spectrometer is disclosed having an elongated orthogonal accelerator (). The orthogonal accelerator () has electrodes () that are transparent to the ions so that ions that are reflected or turned back towards it are able to pass through the orthogonal accelerator (). The electrodes () of the orthogonal accelerator () may be pulsed from ground potential in order to avoid the reflected or turned ion packets being defocused. The spectrometer has a high duty cycle and/or space charge capacity of pulsed conversion.

Multi-pass mass spectrometer with high duty cycle

An ion mirrorconstructed of thin electrodes that are interconnected by resistive dividerswith potentials U-Uapplied to knot electrodes to form segments-of linear potential distribution between the 'knot' electrodes, yet without separating those field regions by meshes. Weak and controlled penetration of electric fields provide for a fine control over the field non linearity and over the equipotential line curvature, thus allowing to reach unprecedented level of ion optical quality: more than twice larger energy acceptance compared to thick electrode mirrors, up to sixth order time per energy focusing, ion spatial focusing and wide spatial acceptance. Novel mirrors can be formed very slim to arrange them into stacks for ion transverse displacement between ion reflections or for multiplexed mirror stacks. Printed circuit boards (PCB) are best suited for making novel ion mirrors, while novel ion mirrors are designed to suit PCB requirements.

Gridless ion mirrors with smooth fields

A multi-reflecting time of flight mass analyser is disclosed in which the ion flight path is maintained relatively small and the duty cycle is made relatively high. Spatial focusing of the ions in the dimension (z-dimension) in which the mirrors () are elongated can be eliminated whilst maintaining a reasonably high sensitivity and resolution.

Multi-reflecting time-of-flight mass spectrometers

Improved ion mirrors () are proposed for multi-reflecting TOF MS and electrostatic traps at various analyzer topologies. Ion mirrors () are constructed of printed circuit boards () with improved precision and flatness. To compensate for the remaining geometrical imperfections of mirror electrodes there are proposed electrode sets () and field structures in the ion retarding region for electronically adjusting of the ion packets time fronts, for improving the ion injection into the analyzer and for reversing the ion motion in the drift direction.

Printed circuit ion mirror with compensation

Improved ion mirrors () (FIG.) are proposed for multi-reflecting TOF MS and electrostatic traps. Minor and controlled variation by means of arranging a localized wedge field structure () at the ion retarding region was found to produce major tilt of ion packets time fronts (). Combining wedge reflecting fields with compensated deflectors is proposed for electrically controlled compensation of local and global misalignments, for improved ion injection and for reversing ion motion in the drift direction. Fine ion optical properties of methods and embodiments are verified in ion optical simulations.

Improved multi-pass time-of-flight mass spectrometers MPTOF, either multi-reflecting (MR) or multi-turn (MT) TOF are proposed with elongated pulsed converters&#x2014;either orthogonal accelerator or radially ejecting ion trap. The converter () is displaced from the MPTOF s-surface of isochronous ion motion in the orthogonal Y-direction. Long ion packets () are pulsed deflected in the transverse Y-direction and brought onto said isochronous trajectory s-surface, this way bypassing said converter. Ion packets are isochronously focused in the drift Z-direction within or immediately after the accelerator, either by isochronous trans-axial lens/wedge () or Fresnel lens. The accelerator is improved by the ion beam confinement within an RF quadrupolar field or within spatially alternated DC quadrupolar field. The accelerator improves the duty cycle and/or space charge capacity of MPTOF by an order of magnitude.

An improved multi-pass time-of-flight or electrostatic trap mass spectrometer () with an orthogonal accelerator, applicable to mirror based multi-reflecting (MR) or multi-turn (MT) analyzers. The orthogonal accelerator () is tilted and after first ion reflection or turn the ion packets are back deflected with a compensated deflector () by the same angle &#x3b1; to compensate for the time-front steering and for the chromatic angular spreads. The focal distance of deflector () is control by Matsuda plates or other means for producing quadrupolar field in the deflector. Interference with the detector rim is improved with dual deflector (). The proposed improvements allow substantial extension of flight path and number of ion turns or reflections. The problems of analyzer angular misalignments by tilting of ion mirror () is compensated by electrical adjustments of ion beam () energy and deflection angles in deflectors () and ().

Ion injection into multi-pass mass spectrometers

Elongation of orthogonal accelerators is assisted by ion spatial transverse confinement within novel confinement means, formed by spatial alternation of electrostatic quadrupolar field (). Contrary to prior art RF confinement means, the static means provide mass independent confinement and may be readily switched. Spatial confinement defines ion beam () position, prevents surfaces charging, assists forming wedge and bend fields, and allows axial fields in the region of pulsed ion extraction, this way improving the ion beam admission at higher energies and the spatial focusing of ion packets in multi-reflecting, multi-turn and singly reflecting TOF MS or electrostatic traps.

Ion guide within pulsed converters

A multi-reflecting time-of-flight mass spectrometer MR TOF with an orthogonal accelerator () is improved with at least one deflector () and/or (R) in combination with at least one wedge field () for denser folding of ion rays (). Systematic mechanical misalignments () of ion mirrors () may be compensated by electrical tuning of the instrument, as shown by resolution improvements between simulated peaks for non compensated case () and compensated one (), and/or by an electronically controlled global electrostatic wedge/arc field within ion mirror ().

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City of Bar, Montenegro

Anatoly Verenchikov