Abstract: 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.

Abstract: Method of isolating ions of selected mass in a quadrupole ion trap of the type including a ring electrode and end caps in which RF and AC voltages are applied to the ring electrode and end caps and scanned to trap a single ion of interest.

Abstract: A simple and economical method of mass analyzing a sample by means of a quadrupole ion trap mass spectrometer in an MS/MS mode comprises the steps of forming ions within a trap structure, changing the RF and DC voltages in such a way that the ions with mass-to-charge ratios within a desired range will be and remain trapped within the trap structure, dissociating such ions into fragments by collisions and increasing the field intensity again so that the generated fragments will become unstable and exit the trap volume sequentially to be detected. A supplementary AC field may be applied additionally to provide various scan modes as well as dissociate the ions.

Abstract: The method of performing chemical ionization and mass analysis with a quadrupole ion trap.

Abstract: A filament assembly which includes spaced posts with slotted ends for positioning a filament. The ends of the filament are secured to the posts in tapered holes which receive a pin or screw to provide electrical contact and tension the filament.

Abstract: A valve assembly for allowing entry of a sampling device or probe device from an ambient atmosphere to a vacuum chamber comprises an electromagnet means which controls a ball made of magnetic material. Upon entry of the device into an entry inlet of the apparatus, the ball is seated in response to activation of the electromagnet means so as to seal an aperture leading to the vacuum chamber. As the device is moved towards the vacuum chamber, the magnetic force is removed, which allows the ball to drop away from the aperture allowing entry of the device into the vacuum chamber. Upon withdrawal of the device from the vacuum chamber, the ball is actuated by the electromagnet to seal the aperture, thereby maintaining the integrity of the vacuum system.

Abstract: 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.

Abstract: In a quadrupole ion store or ion trap type mass spectometer, significantly improved mass selection is achieved by simultaneously trapping ions within the mass range of interest and then scanning the applied RF and DC voltages or the frequency .omega. to sequentially render unstable trapped ions of consecutive specific masses. These are passed out through apertures in an end cap to a high gain electron multiplier to provide a signal indicative of the ion mass. Sensitivity and mass resolution is also enhanced by operating the ion trap at a relatively high pressure in the range 1.times.10.sup.-1 to 1.times.10.sup.-5 torr. The presence of collision gas molecules, such as helium, improves sensitivity and mass resolution. In addition, the structure itself is built of stacked units, sealed by O-rings, which are easily disassembled for cleaning.

Abstract: A mass spectrometer having an ion cyclotron resonance analyzer cell disposed in a homogenous magnetic field with an ionizer outside the magnetic field for forming ions to be analyzed in the cell and an interface for introducing ions from said ionizer into said ion cyclotron resonance cell for analysis.

Abstract: An ionizer for ionizing a sample by bombardment with energetic particles. The ionizer incudes an ion chamber and an adjacent gas discharge region formed with an electrode cooperating wih the ion chamber. Said region serving to discharge a gas to form neutral and charged gas particles. The cooperation of the electrode and chamber accelerates the charged particles and causes charged and uncharged particles to flow into the ion chamber to strike and ionize a sample in the ion chamber.

Abstract: A negative ion detector converts negative ions to positive ions by means of a conversion anode which is maintained at a relatively high positive voltage. The resultant positive ions are detected by a standard continuous dynode electron multiplier which has its detection signal output at ground potential.

Abstract: An ionizer adapted to be placed in a vacuum envelope for providing ions of a sample to be analyzed is disclosed herein and includes an electron source, ion accelerating and focusing electrodes and an interchangeable ionization chamber including a first opening for allowing electrons to enter the chamber and an exit opening to allow ions to exit said chamber. The ionization chamber is supported in cooperative relationship with the electron source and accelerating and focusing electrodes whereby electrons enter the chamber through the first opening and form sample ions in the chamber which then exit the chamber through the exit opening toward said accelerating and focusing electrodes.

Abstract: 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.

Abstract: In a vacuum system a baffle-valve acts first as a baffle to reduce the backstreaming of a diffusion pump fluid into the main vacuum chamber being evacuated and secondly it can be used as a valve to provide complete isolation between the diffusion pump and the vacuum chamber. This enables the chamber to be open for service work while the diffusion pump is kept operating for rapid pump down. The foregoing dual use of the baffle/valve increases pumping efficiency because of higher conductance.

Abstract: In a mass spectrometer a focusing ion lens system effectively separates charged from neutral particles by forming a potential well along the axis from the ionizing region to the mass analyzer by the use of a gridded lens system. The grids by the use of a high-low voltage combination form the potential well while at the same time allowing nonselected neutral particles to pass through the grid. Thus, the system is very effective for relatively high pressure ionizing regions where a large amount of neutral particles are generated.

Abstract: A liquid chromatograph/mass spectrometer interface for permitting the efficient and continuous introduction of an effluent solution from liquid chromatograph into a quadrupole mass spectrometer or any other vacuum analytical system includes a thin ribbon in the form of a loop which at one end receives liquid chromatograph effluent which is passed through one or more vacuum locks to remove residual solvent. At the other end the film of solute or low volatility sample is flash vaporized into the ionization chamber of the mass spectrometer. The interface device is also used to sample dilute solutions from any other source and can be used in a continuous mode, in a single sample mode, or for automatic but intermittent sample introduction.

Abstract: 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.