Abstract: The present invention refers to a pumping stage for turbomolecular pumps comprising a rotor disk (3), integral with a rotating shaft (4) operated by a motor, and a stator disk (1) said stator disk (1), integral with the pump body (2), where the stator disk (1) is a disk whose surface is substantially smooth that can assume, during the evacuation cycle, a bladed configuration, by raising radial sections (5) of the disk surface itself. Raising of radial sections (5) is performed by at least one actuator device (11) controlled, through an electronic control device (12), by a pressure sensor (13) sampling the pressure inside the pump body (2).

Abstract: Improved methods of using an ion trap mass spectrometer, whereby AC voltages supplemental to the AC trapping voltage are used for scanning the trap, for conducting chemical ionization experiments, and for conducting MS.sup.n experiments, are shown. In one embodiment a broadband supplemental AC voltage is applied to rid the trap of ions above or below a preselected cutoff mass. This is particularly useful in conducting chemical ionization experiments for eliminating high mass sample ions that are formed when the reagent gas is ionized by electron impact ionization. Likewise, this technique may be used to eliminate low mass reagent ions when conducting an electron impact ionization experiment in the presence of a reagent gas. In another embodiment a non-resonant, low-frequency supplemental voltage is applied to the trap causing trapped ions to undergo collision induced dissociation. Multiple generations of ion fragments may be simultaneously formed in this manner, thereby enabling MS.sup.n experiments.

Abstract: A variable cooling time is imposed on ions in a quadrupole ion trap prior to excitation through border effect operation. Continuous variation of the cooling time brings about continuous variation of the selected ion internal energy when subjected to the boundary effect such that the boundary effect competes more favorably with ion loss in the trap, and fragmentation reaction channels having successively greater energies of activation can be accessed preferentially.

Abstract: A method and means for accurately regulating the rate of flow of supply gas to the burner or torch of a spectrometer. The flow rate is controlled by a valve having a closure member which is movable between a position at which it provides maximum obstruction to gas flow, and a position at which it provides minimum such obstruction. The closure member movement is controlled by a pulsed electrical signal so that the closure member moves rapidly and repeatedly between each of the two positions. Gas flow rate through the valve is therefore dependent upon the aggregate of the times the closure member spends in either of the two positions referred to, and that flow rate is changed by varying the frequency and/or pulse duration of the pulsed signal.

Abstract: An NMR probe includes a locking collar which is adapted to engage a magnet flange fixed to the NMR magnet. The probe can be removed and reinserted to the same location and orientation.

Abstract: A method for improving sensivity of a QIT by overcoming deleterious space charge effects on the collection of higher mass ions in a QIT by rejecting residual air gas ions during ionization and by rejecting other ions during ionization employing a 1/m/z weighting of the amplitude of each secular frequency, where m/z is the mass to charge ratio of the ions.

Abstract: A gated amplifier drives a gradient coil when the gate signal is applied and the gate signal also controls an FET switch to disconnect a shim power supply from shim coils and connects the shim power supply instead to a dummy load. When the gate signal is removed, the shim coil is restored to operation from the shim power supply.

Abstract: A narrow-band pyrometric system measures the temperature of an object (1), such as a semiconductor wafer (1), that is coated with a film (2) having an absorption band. The thermal radiation emitted by the coated object (1) passes through a lens (3) and aperture (4), and then a filter (5). The passband of this filter (5) falls within the absorption band of the film (2). The transmitted radiation is then collected by the radiation detector (6), which measures the intensity. The detected radiation is at a wavelength where the heated object (1) is substantially opaque, and the effect of uncertainties in the emissivity on the temperature measurement is minimized. Thus, a method is provided to coat the object (1) with a film (2) of material having an absorption band encompassing the filter (5) passband, and a thickness sufficiently great that the object (1) appears opaque when viewed through the filter (5).

Abstract: A method for isolating an ion in a QIT (1) employing values from a mass axis calibration chart to establish the maximum DAC value to scan to in order to scan out m(p)-1 and less during ramp up of RF trapping field while applying a specifically selected fixed supplemental frequency applied during said calibration; and employing values from the calibration curve to establish the DAC value to scan out m(p)+1 and greater during ramping down of RF trapping field, while applying a previously determined fixed broadband spectrum to the QIT end caps.

Abstract: In inductively coupled plasma spectroscopy, the use of an induction coil assembly comprising at least two helical coils which are arranged in overlapping relationship. In one practical form, the overlap is achieved by interlacing of the coils so that at least one turn of one coil is interposed between two adjacent turns of the other coil. For that purpose, the two coils will ideally be of the same diameter and will be coaxial. A tubular part of a plasma torch is contained within the space surrounded by the coil assembly, and a RF energy source is connected to an end of each coil. The other ends of the coils may be connected to ground.

Abstract: Parasitic excitation of an NMR sample is minimized by providing shielding of the sample against RF pick-up from coil leads or like proximate conductive structure in the interior region of the RF coil.

Abstract: A process for manufacturing impellers of turbine pumps provides for subjecting disks corresponding to the impeller to be obtained to electrical discharge machining, using tools in form of plates provided with radial slits extending along at least an arc of circumference and opening into hollow areas. A combined motion of rotation and translation is imparted to the disks, thus generating twisted blades having a profile with defined geometric characteristics. A one-piece rotor can be manufactured employing open tools with slits formed along a semicircumference, and two passages in succession of the workpiece through the tools, moving the workpiece with a combined motion of rotation and translation. An advantageous application of the articles manufactured by this process is for rotors of turbomolecular pumps, since the compression ratio and the pumping speed are optimized and a considerable structural sturdiness of the article is obtained.

Abstract: The cross polarization condition for hetero-coupled NMR spectroscopic investigations for a sample spinning at rate .omega..sub.R is improved by causing at least one of the RF excitation channels to emit pulses in synchronous relationship to the sample spinner during the cross polarization contact whereby dependence of the NMR signal on mechanical spin rate .omega..sub.R is reduced.

Abstract: An NMR probe employs an adjustable RF voltage divider (C.sub.1, C.sub.2 ') comprising a single capacitive impedance switched into or out of the divider by a single 2-pole switch (SP1', SP2').

Abstract: A saddle coil for multiple tuned response is realized by a segmented sequence of first LC elements each tuned to exhibit a low impedance at .omega..sub.1 and a second set of LC elements, each tuned to exhibit a low impedance at .omega..sub.2, at least some of said first set of LC elements having one of said second LC elements in parallel therewith.

Abstract: In a stator assembly for a turbomolecular pump, each stator is assembled from two semicircular portions mutually aligned and secured in place by tongue and grooves means, each such stator including a plurality of radially directed blades connecting an inner circular edge and outer circular edge of the stator, such edges occupying respective parallel displaced planes. The outer edge of each stator includes regularly outward projected tabs which bear between spacer rings to maintain axial alignment.

Abstract: A matrix modifier of finely-divided metallic palladium dispersed to contact a metal constituent to improve analysis of the constituent during graphite furnace atomic absorption spectroscopy. The palladium interacts with a variety of metals in a sample to increase the vaporization temperatures of the metals. One way of contacting palladium with the metal analyte is to introduce it as a salt in solution with the sample into the graphite furnace along with a surfactant. A finely-divided metallic palladium having high surface area is produced in the furnace by introduction of hydrogen gas, which acts as a reducing agent, to reduce and maintain palladium in its metallic form at an early point in the temperature program, prior to evaporation of the surfactant.

Abstract: A liquid nitrogen Dewar includes a spun can for the liquid nitrogen, which spun can is surrounded by an exterior shell. Between the exterior shell and the can is an evacuated space containing a second shell that functions as a radiation shield. The can and both shells are formed of an aluminum alloy having a very high percentage of aluminum. The exterior can surface, interior surface of the exterior shell, and both surfaces of the second shell have clean, non-pitted, smooth, matted, smut free and etched appearances free from discoloration and stains so that these surfaces have low radiation emissivity properties and there is a minimum amount of radiant energy transmitted from the exterior shell to the can and reduced heating of the liquid nitrogen in the can. Each of the surfaces is initially polished, either mechanically, electrochemically or chemically, and then chemically treated with an etchant of nitric acid and hydrofluoric acid for a sufficient duration to achieve the desired appearance.

Abstract: A double-tuned dual port segmented coil for NMR studies of a volume distributed sample is obtained by coupling corresponding junctions of respective segments of two segmented loop portions with legs comprising L.sub.x C.sub.x L.sub.x series combination. Four segment coil portions so coupled support two isolated input ports across C.sub.x for adjacent such legs.

Abstract: A double-tuned circuit is realized from 1/2.lambda..sub.1 transmission lines for connecting a pair of inductors in series at a first frequency and in parallel for a second frequency where said first and second frequencies are in the ratio of a power of two.