Abstract: The invention provides glow discharge optical or mass spectrometers wherein a solid sample may be mounted in a unitary source assembly adjacent to a first electrode means. A second electrode means, spaced from sample by an insulating washer, is also part of the source assembly and engages with a discharge chamber into which a discharge gas is introduced. A glow discharge is maintained in the discharge by a potential differential difference applied between the first and second electrode means. In a mass spectrometer, ions formed in the discharge pass to a mass analyzer, while in an optical spectrometer, optical radiation form the discharge is spectroscopically analyzed. Particularly in the case of a mass spectrometer, the source assembly may be mounted on an insertion probe allowing it to be easily withdrawn from the vacuum envelope to facilitate sample changing and maintenance.

Abstract: A method of mass spectrometry and a mass spectrometer for the analysis of a sample, the mass spectrometer comprising means for producing ions from the sample and a magnetic sector for analyzing the ions, wherein the magnetic field of the magnetic sector is generated by passage of a magnet current controlled by a digital control signal representative of a sequence of integers generated by a computer. According to the invention, means are provided for generating the magnet current in exponential relation to the sequence of integers. In contrast to prior spectrometers, the invention provides peak switching and mass selection across the mass range with a constant number of integer steps per mass peak, thereby facilitating the digital selection of any particular mass peak, particularly those at low mass.

Abstract: Method and apparatus for analyzing organic material present in a surface region (5) of a sample (1), the apparatus comprising: an evacuable sample receiving chamber (2); means (3) for generating an energetic beam (4) of particles or photons and for directing the beam onto the sample whereby to cause the removal therefrom of at least some organic material into a spatial region (7) proximate to the surface region; means (13) for generating non-coherent ultra-violet radiation (14); and means (13) for directing that radiation into the spatial region to photoionize organic material therein; means (35) for mass analyzing resultant ionized species; and means for conducting ions from the spatial region to the means for mass analyzing.

Abstract: The invention relates to a variable dispersion double-focusing mass spectrometer comprising at least a magnetic sector analyzer (4) preceding an electrostatic analyzer (6), which analyzers cooperate to form a direction and velocity focused image on a multichannel detector (34) locatable in a focal plane of the electrostatic analyzer (6). The geometrical parameters of the electrostatic analyzer are selected so that the magnification of the electrostatic analyzer is substantially zero, which makes it possible to use a variable radius electrostatic analyzer to vary the extent of the mass spectrum imaged on the detector (34) while still maintaining double focusing. A variable radius electrostatic analyzer suitable for use in the invention is also described.

Abstract: A method of selecting the resolution of a charged-particle energy or momentum analyzer wherein an analyzing field disperses the particles in an analyzing plane. An electrostatic field generator is adjusted to cause the dispersed particles leaving the field to pass through either of two apertures formed in a resolving aperture member and disposed at different distances from the plane. Each aperture has a different width, selected to result in a different resolution of the analyzing field. A single means for receiving charged particles (typically an ion or electron detector) is disposed to receive particles which have passed through either aperture. A magnetic sector mass spectrometer incorporating the method is also disclosed.

Abstract: There is disclosed a double-focusing mass spectrometer in which ions are generated from a sample in a microwave-induced or inductively-coupled plasma (3). Ions are sampled from the plasma (3) through an aperture in a sampling cone (19) and pass through a skimmer cone (28) and several electrostatic lenses (30,33) to the entrance slit of the mass analyzer. The sampling cone (19) and skimmer cone (28) are maintained by a power supply (40) at a potential approximately equal to the accelerating potential required by the mass analyzer. It is found that the plasma potential may be maintained at such a value that a substantial proportion of the ions generated in the plasma (3) have energies lying within the energy passband of the mass analyzer, so that a high sensitivity, high resolution mass spectrometer especially suitable for the elemental analysis of solid or liquid samples is provided.

Abstract: The invention comprises a mass spectrometer wherein a sample is ionized in a plasma (14), especially an inductively-coupled or microwave-induced plasma. Ions are sampled from the plasma (14) through an orifice (16) in a sampling member (15), a second orifice (37) in a hollow tapered member (19) and a third orifice (53) in a tubular electrode (43). The hollow tapered member (19) comprises a portion (35) both externally and internally tapered with an interior included angle greater than 60.degree., and preferably a shorter externally tapered portion (38) with an external included angle of less than 60.degree.. A tubular extraction electrode 43, preferably comprising a conical end-portion (47) , is disposed within the member (19) for efficiently transmitting the ions into a mass analyzer.

Abstract: A mass spectrometer for the analysis of substances in a gas comprises means for generating a plasma in an enclosure through which a gas flows, conduit means for conveying the gas from the enclosure to a sampling member, and a mass analyzer for mass analyzing ions characteristic of the substances which pass through an aperture in the sampling member. The conduit means is constructed so that a line-of-sight path does not exist between the interior of the enclosure and the aperture in the sampling member. Substances for analysis may be introduced into the gas before or after it passes through the plasma enclosure. When the plasma comprises a pulsed DC glow discharge the spectrometer is useful for the analysis of traces of electrophillic substances in the gas.

Abstract: A method and apparatus for the micro-analysis of a sample surface wherein a mass analyzer is used to analyze secondary ions emitted from the surface in response to the impact of primary radiation. The method comprises: extracting the secondary ions in an electric extraction field maintained by applying an extraction potential difference between the sample and an extraction means, and also maintaining an accelerating potential difference between the sample and the mass analyzer thereby increasing the kinetic energy of the secondary ions to be substantially equal to the energy required for analysis in the mass analyzer; the extraction potential difference being less than the accelerating potential difference. In this way the extraction field can be controlled independently of the accelerating potential between the sample and the mass analyzer.

Abstract: Method and apparatus for the deposition of material onto a substrate, the method comprising evaporating material from a source, controlling the dosage of material at the substrate by moving a shutter between an open position and a closed position, with a closing step comprising beginning to decelerate said shutter before reaching the closed position, subsequently thereby bringing the shutter substantially to rest at the closed position. Preferably the motion of the shutter is substantially harmonic with the acceleration of the shutter being directed towards, and proportional to the distance of the shutter from, the point mid-way between the open and closed positions. Contamination is reduced from prior methods and the invention is especially advantageous in molecular beam epitaxy.

Abstract: An apparatus for the treatment of a sample in a vacuum enclosure having a wall on which a vacuum-tight feedthrough is mounted; the sample being supported on an elongate hollow rotor rotatable about an axis and disposed within the vacuum enclosure, the sample having a front face which is to be treated and also having a rear face; energy conducting means passing from the feedthrough towards the rear face of the sample through the rotor; inner magnet field generator(s) affixed to the rotor; outer magnet field generator(s) mounted to rotate outside of the vacuum enclosure about the axis, the outer magnetic field generator(s) being magnetically coupled to the inner magnet field generator(s), and thereby capable of causing the inner magnet field generator(s) and the rotor to rotate about their common axis; and a source for directing material or radiation at the front face.

Abstract: The invention provides a mass spectrometer comprising an ion source provided with an electron emitting source and magnets which are cooperable to produce a collimated electron beam within the ion source; a mass analyzer; first and second electrodes which cooperate to limit the angular divergence of the ion beam which emerges from the source along the ion beam axis; and magnetic field screens disposed between the first and second electrode means, which reduce the field due to the magnets along the ion beam axis. In this way the mass discrimination introduced by the magnets in prior ion sources is reduced and the accuracy of isotropic ratio measurements is improved.

Abstract: The invention provides a mass spectrometer for the analysis of a sample dissolved in a super-critical fluid. The fluid is expanded directly into an ionization chamber without a liquid-gas transition and the sample is ionized by means of a glow discharge established in the chamber. Preferably the electrodes between which the discharge is struck comprise the wall of the ionization chamber and the tube through which the super-critical fluid enters the chamber. The spectrometer is primarily intended for use with a super-critical fluid chromatograph.

Abstract: The invention provides a method and apparatus for the mass spectrometric determination of the isotopic composition of an element comprised in a sample by gas chromatography-isotopic ratio mass spectrometry. As a sample elutes from the column of the gas chromatograph it enters a sample conversion means which converts the element to an analysis gas (a gas comprising the element in elemental form or in the form of a simple compound, e.g. nitrogen or carbon dioxide) which is admitted into the mass spectrometer only during a second time interval corresponding to the elution of the peak containing the sample from the column. One or more calibration samples of a reference gas are admitted into the spectrometer during first time intervals which do not overlap the second time interval, thereby minimizing the contribution of the analysis gas to the reference gas mass analysis, and vice versa. Various devices are provided to minimize disturbance to the flow of gas into the spectrometer during practice of the method.

Abstract: An ion gun for producing a pulsed microfocused beam of ions comprises an ion source arranged to produce a continuous ion beam along a z-axis toward a collector having an aperture on the axis. A deflector is arranged to maintain the beam substantially stationary and incident on the aperture for a pulse time, to deflect the beam away from the aperture to the collector and subsequently to return the beam to be incident at the aperture. A focussing lens focusses the beam from the deflection point to a final image point, and a condensing lens focusses the beam at the deflection point. A mass filter selects a single ion species, and a second deflector deflects the beam orthogonally to the deflector so that the returning path of the beam on the collector does not cross the aperture. A stigmator and a beam scanner are also provided.

Abstract: The invention provides a mass spectrometer in an optical emission spectrometer having a glow discharge source which is suitable for the analysis of solid non-conducting samples. The source comprises a chamber into which an inert gas is introduced and maintained at a pressure substantially below atmospheric pressure, and two electrodes between which a glow discharge is struck by application of a direct or RF voltage to the electrodes. The cathode electrode comprises the solid non-conducting sample and an auxiliary electrode disposed between the discharge and the sample. The auxiliary electrode comprises an aperture through which the sample is exposed to the discharge. In the case of a mass spectrometer, ions formed in the discharge pass through an aperture in the chamber to a mass analyzer, while in the case of an optical emission spectrometer the chamber is sealed by a window through which radiation generated in the discharge can pass to an optical spectral analyzer.

Abstract: A mass spectrometer (1) suitable for the analysis of the eluent of a liquid or supercritical fluid chromatograph is disclosed. In order to maximize the flow rate of fluid which can be accepted into its ionization chamber (13), aperture closing means (13) are provided between an electron or particle source (27) and an entrance aperture (40) into the ionization chamber through which electrons or particles enter the chamber when required to ionize the sample therein. The aperture closing means are operable to close said aperture when such ionization is not required, thereby increasing the maximum flow rate into the ionization chamber. Sample ionization may then be effected by means of a glow discharge in the chamber or by a liquid ionization process such as thermospray ionization.

Abstract: An apparatus and method providing a bakeable sealing means for a vacuum system, and thereby an improved bakeable ultra-high vacuum system; the apparatus comprising: a first sealing element composed substantially of an elastomeric material; a second sealing element comprising PTFE; and means for engaging the first sealing element with the second sealing element and for compressing the first sealing element; as for example in an improved bakeable seal between a first and a second flange, or in a gate valve, or a vacuum chamber entry lock.

Abstract: The invention comprises a mass spectrometer adapted for the determination of isotopic ratios which has several ion-collecting means disposed along its mass focal plane. Separate current amplifier means are provided for each ion collecting means and comprise an electrometer amplifying element, and an input resistor disposed in an inner box, itself disposed within a sealed evacuated housing. Means are provided for cooling the amplifier element to a temperature substantially below 20.degree. C. Means are provided for maintaining the temperature of at least the input resistor substantially constant. Cooling the amplifier element, typically to between 0.degree. and 5.degree. C., results in an unexpected reduction in low frequency noise which allows the time required to determine an isotope ratio to be reduced, thereby substantially increasing sample throughout.

Abstract: There is provided an electron spectrometer operable to produce an image of an electron emitting surface, said spectrometer comprising in sequence:(a) means for causing electrons to be emitted from said surface;(b) a first electrostatic lens system arranged to project at least some of said electrons onto a first diffraction plane as a Fourier transform of an electron image of at least a part of said surface;(c) a torroidal capacitor type electrostatic energy analyzer having an object plane and conjugate thereto a first image plane, said analyzer being disposed with said object plane coincident with said first diffraction plane and being arranged to project electrons of said Fourier transform as an energy dispersed Fourier transform in said first image plane;(d) energy selection means for transmitting electrons of said energy dispersed Fourier transform having energies only within a selected range; and(e) a second electrostatic lens system arranged to receive electrons transmitted by said energy selection means