Abstract: An electrode for use in a reduced pressure region in a mass spectrometer whereby the electrode is subject to deposition of dielectric (non-conducting) substances thereon, which can cause unstable performance of the mass spectrometer. The surface portion of the electrode that is for providing an equipotential boundary of an electric field for influencing charged particles is made rough, in contrast to the prior art of providing a polished surface. The rough surface provides projections and cavities, which may have a regular or irregular occurrence, which it has been found significantly reduces the deposition of dielectric substances from the charged particles thereon. A preferred structure is for a rod electrode (42) to have a screw thread (44) formed thereon whereby the thread crests (43) along the rod electrode provide projections (43) and the thread roots (45) provide cavities.

Abstract: The invention relates to a method of creating multipole systems carrying RF voltage which can be used as ion guides, mass-selective quadrupole filters or collision cells to fragment ions; and multipole systems manufactured according to this method. The invention provides a method which produces particularly inexpensive multipole systems by spark erosion with a wire cathode. The multipole rod system comprises only two pieces of metal for connection to the two phases of the RF voltage, and the two pieces of metal are adjusted with respect to each other by one or more identical insulating rings.

Abstract: An improved ion funnel design is disclosed that decreases the axial RF (parasite) fields at the ion funnel exit. This is achieved by addition of one or more compensation electrodes after the conductance limit electrode. Various RF voltage profiles may be applied to the various electrodes minimizing the parasite axial potential wells. The smallest RF aperture that serves as the conductance limiting electrode is further reduced over standard designs. Overall, the ion funnel improves transmission ranges of both low m/z and high m/z ions, reducing RF activation of ions and decreasing the gas load to subsequent differential pumping stages.

Abstract: An ion spectrometer apparatus is disclosed having an ion source, an ion mobility spectrometer device such as a FAIMS cell, and a capillary for transporting ions from the ion source to the entrance of the FAIMS cell. The capillary is heated to promote evaporation of solvent from incompletely desolvated droplets entering the capillary inlet, thereby preventing or minimizing operational problems associated with the presence of wet material in the FAIMS cell. The FAIMS cell may be used to selectively transmit ions to a mass analyzer.

Abstract: Methods for applying an RF field in a two-dimensional electrode structure include applying RF voltages to main electrodes and to compensation electrodes. The voltages on the compensation electrodes may be adjusted to be proportional to the voltages on the main electrodes. The adjustment(s) may be done to optimize the RF field for different modes of operation such as ion ejection and ion dissociation. For dissociation, a supplemental RF dipole may be applied, or two mutually orthogonal dipoles may be applied in phase quadrature to form a circularly polarized field. Electrode structures may include main trapping electrodes, one or more compensation electrodes, one or more ion exit apertures, and means for applying the various desired voltages.

Abstract: A switchable branched ion guide is disclosed. The switchable branched ion guide includes a trunk section, first and second branch sections, a junction connecting the trunk section to the branch sections, and a movable valve member located at the junction. The valve member may be moved between a first position in which ion travel is permitted between the trunk section and first branch section and is inhibited between the trunk section and the second branch section, and a second position in which ion travel is permitted between the trunk section and the second branch section and is inhibited between the trunk section and the first branch section. The branched ion guide may be utilized, for example, to controllably switch an ion stream between two destinations such as mass analyzers.

Abstract: A mass spectrometer includes: an ion source for ionizing a specimen to generate ions, an ion transport portion for transporting the ions, a linear ion trap portion for accumulating the transported ions by a potential formed axially, and a control portion of ejecting the ions within a second m/z range different from a first m/z range, from the linear ion trap portion, and substantially at the same timing as the timing of accumulating the ions within the first m/z range from the transport portion into the linear ion trap portion. The ion transportation portion having a mass selection means for selecting the ions in the first m/z range.

Abstract: A system and method are disclosed for effectively compensating for an unbalanced or non-zero centerline radio-frequency potential in a quadrupolar ion trap, the unbalanced centerline potential created by a compensation feature that minimizes non-linear field components created by one or more ejection slots in the ion trap. The ion trap includes a centerline that passes longitudinally through a trapping volume inside of the ion trap, a pair of Y electrodes with inner Y electrode surfaces that are approximately parallel to the centerline, and a pair of X electrodes with inner X electrode surfaces that are approximately parallel to the centerline. The X electrodes have ejection slots through which trapped ions are ejected from the ion trap. A Y signal with a Y signal amplitude is coupled to both of the Y electrodes. An X signal with an X signal amplitude is coupled to both of the X electrodes.

Abstract: An apparatus and method are disclosed for efficient detection of ions ejected from a quadrupolar ion trap, in which the ions are ejected as first and second groups of ions having different directions. The first and second groups of ions are received by a conversion dynode structure, which responsively emits secondary particles that are directed to a shared detector, such as an electron multiplier. The conversion dynode structure may be implemented as a common dynode or as two dynodes (or sets of dynodes), with each dynode positioned to receive one of the groups of ions.

Abstract: A system and method are disclosed for effectively compensating for non-linear field components created by a field distortion feature in a quadrupolar ion trap, compensation provided by a geometric surface shaping which reduces the non-linear field components and creates a minimal centerline radio-frequency potential in the ion trap. The ion trap includes a centerline that passes longitudinally through a trapping volume inside of the ion trap, a pair of Y electrodes with inner Y electrode surfaces that are approximately parallel to the centerline, and a pair of X electrodes with inner X electrode surfaces that are approximately parallel to the centerline. The X electrodes have one or more ejection slots through which trapped ions are ejected from said ion trap. The inner Y electrode surfaces each have a Y radius of curvature, and the inner X electrode surfaces each have an X radius of curvature. The X radius of curvature is selected to be smaller than the Y radius of curvature.

Abstract: An ion guide having a plurality of spheroidal or similarly shaped electrodes is disclosed. The electrodes are arranged in pairs about a central ion flow axis, and an RF voltage is applied in a prescribed phase relation to create an electric field that focuses and radially confines an ion beam. A defocusing effect associated with the electrode shape may be reduced by placement of a separate skirt electrode immediately downstream in the ion path, or by forming the electrodes in a composite structure, whereby the trailing portion of the electrode is fabricated from or coated with an insulative material.

Abstract: An electrode network for N parallel ion traps, wherein N is an integer larger than 1, includes at most 2N+2 electrodes, which form N trapping volumes each corresponding to a respective one of the N parallel ion traps. Also provided is a parallel mass spectrometer, comprising: a vacuum chamber and a network of at most 2N+2 electrodes disposed in the vacuum chamber and held in fixed positions with respect to each other, the network of electrodes forming N trapping volumes each corresponding one of N parallel ion traps. The network of electrodes may be arranged in first and second rows of electrodes. A plurality of detectors is positioned to receive ions ejected from the trapping volumes through spaces between adjacent electrodes in the first row of electrodes.

Abstract: A system and method for separating ions in an ion mixture, such as a plasma in space. The ion mixture enters an electrostatic analyzer, whose ion path has at least two sections. A first section applies a DC voltage to the ions, and a next section applies an RF frequency voltage to the ions. Appropriate DC and RF voltages are applied, such that at least a portion of the lower mass ions are absorbed into the RF section of the analyzer. The heaver ions are transmitted out of the ion path and are readily available for further analysis.

Abstract: Systems and methods of the invention include a branched radio frequency multipole configured to act, for example, as an ion guide. The branched radio frequency multipole comprises multiple ion channels through which ions can be alternatively directed. The branched radio frequency multipole is configured to control which of the multiple ion channels ions are directed, through the application of appropriate potentials. Thus, ions can alternatively be directed down different ion channels without the use of a mechanical valve.

Abstract: According to an aspect of the present invention, there are provided an ion trap mass spectrometry method and an ion trap mass spectrometry device using a mass spectrometer, the mass spectrometer including: an ion source part for ionizing a sample; an ion trap part for trapping ions generated in the ion source; a main high frequency power source for applying a main high frequency voltage to the ion trap part, and an auxiliary high frequency power source for applying an auxiliary high frequency voltage thereto; and a detector for detecting the ions ejected from the ion trap. The ion trap mass spectrometry method and the ion trap mass spectrometry device includes the steps of: accumulating desired ions into the ion trap part by ejecting undesired ions while accumulating ions into the ion trap part; and ejecting undesired ions that remain in the ion trap part and leaving the desired ions in the ion trap part are repeated alternately.

Abstract: An improved ion funnel design is disclosed that decreases the axial RF (parasite) fields at the ion funnel exit. This is achieved by addition of one or more compensation electrodes after the conductance limit electrode. Various RF voltage profiles may be applied to the various electrodes minimizing the parasite axial potential wells. The smallest RF aperture that serves as the conductance limiting electrode is further reduced over standard designs. Overall, the ion funnel improves transmission ranges of both low m/z and high m/z ions, reducing RF activation of ions and decreasing the gas load to subsequent differential pumping stages.

Abstract: The invention provides, in various embodiments, systems and methods relating to controlling ion behavior in an ion-based analysis system.

Abstract: The invention relates to instruments for storing ions in more than one ion storage device and to the use of the storage bank thus created. The ion storage bank includes several storage cells configured as RF multipole rod systems, where the cells contain damping gas and are arranged in parallel. Each pair of pole rods is used jointly by two immediately adjacent storage cells such that the ions collected can be transported from one storage cell to the next by briefly applying DC or AC voltages to individual pairs of pole rods. The ions can thus be transported to storage cells in which they are fragmented or reactively modified, or from which they can be fed to other spectrometers. In particular, a circular arrangement of the storage cells on a virtual cylindrical surface makes it possible to accumulatively fill the storage cells with ions of specific fractions from temporally sequenced separation runs.

Abstract: An apparatus and method for improved inline and automated chemical analysis is provided, in particular disclosing signal optimization for an electrospray ionization mass spectrometer apparatus. A substantially inert pathway for ion analysis is provided by using substantially inert metals or polymers for pathway parts. Other enhancements and advantages are also disclosed, including an advantageous probe profile and metal foil cover.

Abstract: Methods and apparatus are described for efficient photodetachment and purification of negative ion beams. A method of purifying an ion beam includes: inputting the ion beam into a gas-filled multipole ion guide, the ion beam including a plurality of ions; increasing a laser-ion interaction time by collisional cooling the plurality of ions using the gas-filled multipole ion guide, the plurality of ions including at least one contaminant; and suppressing the at least one contaminant by selectively removing the at least one contaminant from the ion beam by electron photodetaching at least a portion of the at least one contaminant using a laser beam.

Abstract: Multiple ionization ion sources and multiple mass analyzers are combined into one mass spectrometer instrument by a six-electrodes ion trap or an array of six-electrodes ion traps. The six-electrodes ion trap can be operated as an independent two-dimensional ion guide or linear ion tap in an arbitrarily selected direction among three orthogonal XYZ directions. The two-dimensional ion guide/linear ion trap can be alternated from one direction to another among the three orthogonal directions electrically. A six-electrodes ion trap generates six equivalent importing and exporting interfaces, each of the interfaces can be used to trap external ions and transfer the trapped ions to any of the other five interfaces. The six-electrodes ion trap provide a mass spectrometer with versatility, multiply functions, high duty-cycles and high sample throughput.

Abstract: A device for manipulating ions which includes a perforated folder of electrically conductive material, a first electrode fixed to the holder and a second electrode extending parallel to the first electrode and spaced from the first electrode and holder. The second electrode is connected to the holder through a rigid support of electrically insulated material.

Abstract: A two-dimensional ion trap comprises a first and second trapping plate located in a first and second terminals of the ion trap device, a set of four predetermined surface-shaped rods located in the center, a set of electrodes located between the set of four predetermined surface-shaped rods, and a control circuitry for applying a predetermined voltage to said first and second trapping plates.

Abstract: A variable duty cycle ion source assembly is coupled to a continuous beam mass spectrometer. The duty cycle can be adjusted based on previous scan data or real time sampling of ion intensities during mass analysis. This provides the ability to control the total number of ions formed, mass analyzed and detected for each ion mass of interest. The frequency of the ion source can be sufficiently high (kHz range) so as to maintain accurate peak centroiding. The ion source assembly can be used for both electron ionization (EI) or chemical ionization (CI) modes of operation.

Abstract: A method for manipulating ions in an ion trap includes storing ions, spatially compressing, and ejecting selected ions according to mass-to-charge ratio. An ion trap includes an injection port, an arm having a first and a second end for confining and spatially compressing the ions, and an ejection port for ejecting the ions from the second end. The arm includes two pairs of opposing electrodes, which provide a quadrupole electric field potential at any cross-section of the ion trap. The distance between opposing electrodes and the cross-sectional area of the electrodes increases from the first to second end. The electrodes may be tapered cylindrical rods or of hyperbolic cross-section. Ions selected for ejection are spatially compressed into a region at the second (wider) end. The ion trap may include one arm, with either orthogonal or axial ejection, or two arms with a central insert for orthogonal ejection.

Abstract: An apparatus that is or includes an ion trap, wherein the ion trap comprises an injection endcap, an extraction endcap, a plurality of ring electrode segments collectively positioned in substantially coaxial alignment between the injection and extraction endcaps, and a plurality of insulators each interposing neighboring ones of the plurality of ring electrode segments.

Abstract: A linear trap which allows for charge separation and ion mobility separation in a speedy manner, and enables measurement with high duty cycle. A mass spectrometer comprises an ion source, an ion trap for trapping ions ionized by the ion source, an ion trap controller for controlling a voltage on an electrode included in the ion trap, and a detector for detecting the ions ejected from the ion trap. The ion trap controller includes a table for each mass-to-charge ratio, the table containing a frequency of the voltage used for charge separation, and a gain of the voltage for ejecting a first ion with a first charge outside the ion trap, and retaining in the ion trap a second group of ions with a second charge that is lower than that of the first charge. The ion trap controller controls the voltage based on the mass-to-charge ratio set. The mass spectrometer has significantly improved sensitivity, as compared to the prior art.

Abstract: An apparatus and method for providing direct liquid sample introduction using a nebulizer are provided. The apparatus and method include a short torch having an inner tube and an outer tube, and an elongated adapter having a cavity for receiving the nebulizer and positioning a nozzle tip of the nebulizer a predetermined distance from a tip of the outer tube of the short torch. The predetermined distance is preferably about 2-5 mm.

Abstract: A method for processing ions in mass spectrometry is provided. The method provides for processing ions in a ion processing cell having elongated segmented rods, a circuit for applying RF voltages and a circuit for applying DC voltage selectively to the segments of the segmented rods. The method comprises applying an RF field to the elongated volume, applying DC voltage selectively to the segments to form a plurality of potential regions having discrete potentials; providing analyte ions to a first potential region and processing at least a portion of the analytes in the first potential region. In one embodiment, the potential region is a potential well.

Abstract: The present invention relates to an apparatus and method for focusing, separating, and detecting gas-phase ions using the principles of electrohydrodynamic quadrupole fields at high pressures, at or near atmospheric pressure. Ions are entrained in a concentric flow of gas and travel through a high-transmission element into a RF/DC quadrupole, exiting out of the RF/DC quadrupole, and then impacting on an ion detector, such as a faraday plate; or through an aperture or capillary tube with subsequent identification by a mass spectrometer. Ions with stable trajectories pass through the RF/DC quadrupole while ions with unstable trajectories drift off-axis collide with the rods and are lost. Alternatively, detection of ions with unstable trajectories can be accomplished by allowing the ions to pass through the rods and be detected by an off-axis detector.

Abstract: A mass spectrometer is disclosed comprising a guide wire ion guide 1 having an outer cylindrical electrode 2 and an inner guide wire electrode 3. AC and DC potential differences are maintained between the outer electrode 2 and the inner electrode 3 so that ions are radially confined within the ion guide 1 in an annular potential well. The outer electrode 2 may be segmented and axial potential wells created along the length of the ion guide 1 may be translated along the length of the ion guide 1 by applying additional transient DC potentials to the segments forming the outer electrode 2.

Abstract: In one implementation, processes for designing mass separators from a series of mass separator electric field data and processes for designing an ion trap from a range of data pairs and a mass analyzer scale are provided. Methods for producing mass separators including ion traps having Z0/r0 ratios from about 0.84 to about 1.2 are also provided. Mass spectrometers are al provided that can include mass separators in tandem with one being an ion trap having a Zo/ro ratio between 0.84 and 1.2. The present invention also provides methods for analyzing samples using mass separators having first and second sets of components defining a volume with a ratio of a distance from the center of the volume to a surface of the first component to a distance from the center of the volume to a surface of the second component being between 0.84 and 1.2.

Abstract: The invention provides a multipole ion trap. The trap has a longitudinal axis. An oscillating on-axis potential is set up along the longitudinal axis, providing a potential well in which ions are trapped. In some embodiments, rods forming the poles are symmetrically and equidistantly positioned about the longitudinal axis and RF signal with different magnitudes are applied to the poles. In other embodiments, the rods are not positioned symmetrically about the longitudinal axis and the RF signals applied to the poles may have the same or different magnitudes. Poles used in the invention may include two or more rods. An ion trap according to the invention may include more than two poles, and in some embodiments, a third or additional pole may be added to provide the oscillating on-axis potential. The ion trap may be used mass selectively scan ions, fragment ions and to trap and separate differently charged ions, among other uses.

Abstract: A quadrupole ion trap device has a field adjusting electrode located outside the trapping region adjacent the aperture in the entrance end cap electrode, and optionally adjacent the aperture in the exit end cap electrode. The field adjusting electrode(s) controls field distortion in the vicinity of the apertures. By appropriately setting the voltages on the field adjusting electrodes the efficiency and resolution of operational processes such as ion introduction, precursor ion isolation and mass scanning can be improved.

Abstract: Disclosed is a high field asymmetric waveform ion mobility spectrometer (FAIMS) including a set of spaced-apart parallel rods, the space between the parallel rods having first and second ends and defining an analyzer region. The apparatus includes an electrical controller for electrically coupling to the set of parallel rods, for applying at least an rf-voltage between the parallel rods of the set of parallel rods in a first operating mode and for applying a combination of an asymmetric waveform voltage and a direct current voltage between the parallel rods of the set of parallel rods in a second operating mode.

Abstract: The method of the present invention is to select ions having a predetermined mass to charge ratio by applying an ion selecting electric field in an ion storage space of an ion storage device. The method is characterized in that the ion selecting electric field is generated to be proportional to a product of a) a base wave composed of a repetition of a unit wave of a constant amplitude and a predetermined pattern, and b) an amplitude pattern which changes continuously. The amplitude pattern is preferred to increase as time passes in order to gradually increase the intensity of the ion selecting electric field applied to the ion storage space until ions of a desired mass to charge ratio are selected. The unit wave may be generated by the FNF method or by the SWIFT method. Further, it is effective to increase the intensity of the frequency components of the unit wave as the frequency is further from the characteristic frequency of the object ion having a desired mass to charge ratio.

Abstract: An apparatus and method for correcting deviations in a quadrupole field in a quadrupole ion trap is provided. More specifically the invention provides for correction electrodes positioned in at least one primary quadrupole electrode and a method of using the correction electrodes to provide a field correction potential.

Abstract: Apparatus and method for trapping uncharged multi-pole particles comprises a bound cavity for receiving the particles, and a multiplicity of electrodes coupled to the cavity for producing an electric field in the cavity. In a preferred embodiment, the electrodes are configured to produce in the electric field potential both a multi-pole (e.g., dipole) component that aligns the particles predominantly along an axis of the cavity and a higher order multi-pole (e.g., hexapole) component that forms a trapping region along the axis. In one embodiment, the electrodes and/or the particles are cooled to a cryogenic temperature.

Abstract: The invention relates to a method for damping the kinetic energy of ions in ion cells filled with collision gas and with an exit aperture to drain the ions out of the cell. The invention uses a conditioning cell with an adjustable DC potential which decreases towards the exit aperture to compress the phase volume of the ions by damping their kinetic energies, collecting the ions after thermalization in the spatial potential minimum thus created and letting them drain away relatively slowly through a central potential minimum in the exit aperture system. This facilitates the production of very fine, highly parallel ion beams which consist of almost monoenergetic ions. In particular, the method can also be coupled with a fragmentation of the ions.

Abstract: Ion injection in a drift tube apparatus for mobility spectrometry was accomplished without conventional ion shutters such as the Bradbury-Nielson or similar designs common to such drift tubes. Instead ions were passed between the ion source and drift region by using time-dependent electric field gradients that act as ion barriers between ordinary drift rings. Benefits of this design are simplicity and mechanical robustness. This ion injection technique dynamically accumulates the ions created between shutter grid pulses, as does the Bradbury-Nielson method. The invention provides not only structural improvements to the well known apparatus, but also provides inventive methods for operating a drift tube apparatus in achieve maximum analyte injection efficiency and improving ion detection sensitivity. Improving ion detection sensitivity of drift tubes has practical experimental application. Incorporation of the inventive apparatus into a smoke detector is a further practical application of the invention.

Abstract: A mass spectrometer 10 comprises an ion source 12 which generates nebulized ions which enter an ion cooler 20 via an ion source block 16. Ions within a window of m/z of interest are extracted via a quadrupole mass filter 24 and passed to a linear trap 30. Ions are trapped in a potential well in the linear trap 30 and are bunched at the bottom of the potential well adjacent an exit segment 50. Ions are gated out of the linear trap 30 into an electrostatic ion trap 130 and are detected by a secondary electron multiplier 10. By bunching the ions in the linear trap 30 prior to ejection, and by focussing the ions in time of flight (TOF) upon the entrance of the electrostatic trap 130, the ions arrive at the electrostatic trap 130 as a convolution of short, energetic packets of similar m/z. Such packets are particularly suited to an electrostatic trap because the FWHM of each packet's TOF distribution is less than the period of oscillation of those ions in the electrostatic trap.

Abstract: There is provided an ion-mobility spectrometer. This apparatus includes the following configuration components: An ion source for generating first ions, a first drift unit for separating the first ions by flight drift times, an ion dissociation unit for generating second ions by dissociating the first ions separated, and a second drift unit for separating the second ions by flight drift times. Moreover, the first drift unit, the ion dissociation unit, and the second drift unit are located inside a chamber whose pressure is set at 10 mTorr or higher. This apparatus allows execution of low-cost and high-resolving-power ion separation and detection.

Abstract: An apparatus for multiple nano-spray delivery of a sample to FAIMS analyzer includes a micro-machined ionization source having a plurality of discrete nozzles. At least some of the discrete nozzles of the plurality are aligned one each with an ion inlet of a plurality of discrete ion inlets of the FAIMS, so that ions produced at different discrete nozzles are introduced into different portions of the FAIMS analyzer region. The ions that are introduced via each ion inlet are at least partly separated prior to adding/mixing with the ions introduced via other ion inlets. This reduces the problems of ion-ion electric repulsions that occur when ion density is high.

Abstract: The present invention relates to an apparatus for delivering ions to a vacuum chamber. The apparatus comprises an ionization chamber, an ionization region within the ionization chamber, a vacuum interface at a vacuum interface voltage and a vacuum chamber, wherein the ionization chamber communicates with the vacuum chamber through the vacuum interface. Sample is introduced into the ionization chamber from an electrospray assembly at approximately ground potential. Two electrodes are provided within the chamber such that three electric fields are generated, a first field extending from the electrospray assembly to the first electrode, a second field extending from the second electrode to the first electrode, and a third field extending from the second electrode to the vacuum interface. Ions are forced to travel through the fields in order before entering the vacuum chamber. In addition, the invention provides a method of delivering ions to a vacuum chamber.

Abstract: An electron impact ion source includes an ionization chamber in which a first rf multipole field can be generated and an ion guide positioned downstream from the ionization chamber in which a second rf multipole field can be generated wherein electrons are injected into the ionization chamber along the axis (on-axis) to ionize an analyte sample provided to the ionization chamber.

Abstract: A mass analyzer includes: an ion trap device including an ion trapping space surrounded by a plurality of electrodes; a time-of-flight mass analyzer for determining a mass to charge ratio of ions ejected from the ion trapping space; a trapping voltage generator for generating an ion trapping RF voltage to at least one of the plurality of electrodes; an ejecting voltage generator for generating an ejecting voltage to at least one of the plurality of electrodes to form an ion ejection electric field for ejecting ions trapped in the ion trapping space; and a controller for stopping the ion trapping RF voltage at a timing when ions are trapped in the ion trapping space and the ion trapping RF voltage is at a predetermined phase, and for applying the ion ejecting voltage a predetermined period after the ion trapping RF voltage is stopped.

Abstract: In the mass spectrometer of the present invention, the controller controls the time of changing the voltage applied to the electrode or electrodes of the ion trap from the ion trapping voltage to the ion ejecting voltage according to the polarity of the electric charge of ions to be ejected from the ion trap. Since positively charged ions and negatively charged ions move in the same direction if the phases of the RF voltage for generating the ion trapping electric field in the ion trap are reversed, the controller may reverse the phase of the RF voltage for trapping ions according to the polarity of the electric charge of ions when the ion ejecting time is fixed, irrespective of the polarity of the electric charge of ions to be ejected. Alternatively, the controller may change the ion ejecting time by half a cycle of the RF voltage depending on the polarity of the electric charge of ions when the ion trapping RF voltage is maintained the same.

Abstract: An ion mobility spectrometer is provided including at least one ionization chamber (1), which can be passed through by analyte-containing gas and at least one radiation source (2), from which ionizing radiation which is suitable for at least partially ionizing the analyte-containing gas enters the ionization chamber (1). At least one transition area (3) is provided, into which the at least partially ionized gas as ion carrier gas (4) and an almost ion-free gas as drift gas (5) can be charged in a way that, at least at the end of the transition area (3), a flow is established, in which cross-sectional areas (6) are mainly passed through by ion carrier gas (4) and other cross-sectional areas (7, 7?) are mainly passed through by drift gas (5).

Abstract: In some embodiments, a tandem (MS/MS) mass spectrometry method includes selecting a collision-induced dissociation (CID) voltage amplitude and a q-parameter value for a quadrupole ion trap to optimize a daughter ion fragmentation process for a given parent ion mass-to-charge (m/z) ratio. The q and CID voltage values may be selected according to a look-up table and/or using approximate analytical expressions. The correspondence between m/z values and (q, CID) value pairs may be established by pre-measurement calibration. A fragmentation-optimized q value may be computed according to m/z, and a CID voltage value may be determined according to the computed q value. A user may also force q to another value, for example in order to facilitate trapping of a desired daughter ion mass range, and the controller computes a CID voltage value according to the forced q value.

Abstract: A mass spectrometer adopting a differential pumping system includes an ionization chamber with substantially atmospheric pressure, two intermediate vacuum chambers, and a mass analyzing chamber with a very low pressure (or a very high vacuum), where the pressures of these chambers are in the order of higher to lower. A hole is provided in every wall between two adjoining chambers for allowing ions to be mass analyzed to pass through. An auxiliary electrode with an aperture is placed near the hole, and an AC voltage is applied to the auxiliary electrode. Owing to an AC electric field generated by the AC voltage around the hole, an ion coming near the hole is exerted with such a force that confines the ion to the ion optical axis C. Under these circumstances, even when the ion collides with a residual gas molecule or atom and is deflected away from the ion optical axis, the confining force exerted by the electric field pulls the ion back toward the ion optical axis.