Abstract: A front-end reagent ion source for a mass spectrometer is disclosed. Reagent vapor is supplied to a reagent ionization volume located within a chamber of the mass spectrometer and maintained at a low vacuum pressure. Reagent ions are formed by interaction of the reagent vapor molecules with an electrical discharge (e.g., a glow discharge) within the ionization volume, and pass into the chamber of the mass spectrometer. At least one ion optical element located along the analyte ion path transports the reagent ions to successive chambers of the mass spectrometer. The reagent ions may be combined with the analyte ions to perform ion-ion studies such as electron transfer dissociation (ETD).

Abstract: A front-end reagent ion source for a mass spectrometer is disclosed. Reagent vapor is supplied to a reagent ionization volume located within a chamber of the mass spectrometer and maintained at a low vacuum pressure. Reagent ions are formed by interaction of the reagent vapor molecules with an electrical discharge (e.g., a glow discharge) within the ionization volume, and pass into the chamber of the mass spectrometer. At least one ion optical element located along the analyte ion path transports the reagent ions to successive chambers of the mass spectrometer. The reagent ions may be combined with the analyte ions to perform ion-ion studies such as electron transfer dissociation (ETD).

Abstract: A front-end ion source for a mass spectrometer generates both analyte and reagent ions. The reagent source may include a heater for vaporizing a condensed-phase reagent substance and an electron source for ionizing reagent molecules. The interior of the reagent ionization chamber is purged with a purge gas to avoid or minimize reaction of the reagent ions with oxygen or other reactive species, thereby enabling operation of the reagent ionization chamber at or near atmospheric pressure. The reagent and analyte ions are directed into a reduced-pressure chamber through separate passageways. An ion transport optic selectively transmits one of the analyte ions or the reagent ions from the reduced-pressure chamber to downstream regions of the mass spectrometer.

Abstract: An improved method of mass analyzing a sample in a three-dimensional quadruple ion trap with varying fields is disclosed. The dynamic range and sensitivity of previous methods is increased by controlling the number of sample ions formed in the ion trap to avoid saturation and space charge.

Abstract: A chromium or oxidized chromium surface for use in sample analyzing and ionizing apparatus, such as an ion trap or ionization chamber, which does not degrade or decompose a sample in contact with the surface.

Abstract: A segmented electron multiplier is disclosed with front and rear sections. The sections are specially designed so that the length of the rear section compared to the length of the front section is no less than 4:1. This permits multiple replacements of the rear section, after the multiplier wears out, without any unsatisfactory drop in the overall electrical gain produced by the repaired device. In the preferred embodiment, the front portion is a funnel having a tubular stem, and the rear portion is a straight tube with a cylindrical helical inner channel. The length-to-length split is 5:1, which theoretically permits up to six or seven replacements of the rear section before unsatisfactory gain occurs.

Abstract: A mass spectrometer including at least one mass analyzer into which an ion beam to be analyzed is projected having a collision surface means in-line with the ion beam to form surface collision products which are directed into the in-line mass analyzer.

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 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: 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: A method and an apparatus are disclosed for adapting a conventional quadrupole mass spectrometer to substantially simultaneously produce and record both positive and negative ions. The apparatus includes a control circuit for rapidly switching the repeller, source and lens electrodes of a quadrupole mass spectrometer between positive and negative potentials. This switching of the potentials, along with the selection of appropriately favorable ionization conditions, permits the generation of suitable streams of positive and negative ions. A dual electron multiplier detector is used for separately sensing the positive and negative ions transmitted through the quadrupole mass spectrometer. The disclosed method and apparatus are particularly suitable for obtaining accurate mass measurements using a quadrupole mass spectrometer.

Abstract: A method and an apparatus are disclosed for adapting a conventional quadrupole mass spectrometer to substantially simultaneously produce and record both positive and negative ions. The apparatus includes a control circuit for rapidly switching the repeller, source and lens electrodes of a quadrupole mass spectrometer between positive and negative potentials. This switching of the potentials, along with the selection of appropriately favorable ionization conditions, permits the generation of suitable streams of positive and negative ions. A dual electron multiplier detector is used for separately sensing the positive and negative ions transmitted through the quadrupole mass spectrometer. The disclosed method and apparatus are particularly suitable for obtaining accurate mass measurements using a quadrupole mass spectrometer.

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..]. .Iadd.Apparatus for detecting the abundance of negative ions from a source of negative ions, having a first conversion dynode and an electron multiplier, the electron multiplier having a second conversion dynode. The first conversion dynode is operated at a high positive potential to attract the negative ions whereby the negative ions impact the first conversion dynode with a substantial portion of the negative ions being converted to secondary positive ions.

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.