Abstract: A plurality of objects are concurrently studied in a common MRI apparatus wherein the RF excitation is distributed to one plurality of K RF coils of N said pluralities of RF coils and one of each of said N is switched to a corresponding one of K RF receivers. The interaction of the several coils is further minimized by selectably detuning each coil except for an active coil(s).

Abstract: A housing for microelectronic devices requiring an internal vacuum for operation, e.g., an image detector, is formed by tape casting and incorporates leads between interior and exterior of said housing where said leads are disposed on a facing surface of green tape layers. Adjacent green tape layers having corresponding apertures therein are stacked on a first closure member to form a resulting cavity and increased electrical isolation or channel sub-structures are achievable by forming adjacent layers with aperture dimension which vary non-monotonically. After assembly of the device within the cavity, a second closure member is sealed against an open face of the package in a vacuum environment to produce a vacuum sealed device.

Abstract: Increased distributed capacitance for an NMR resonant probe coil is obtained by a surrounding conducting surface which is congruent to and spaced from the major portion of the RF current density distribution on the surface of the inductive component of the resonator. This surface is interrupted with one or more gaps to avoid or control circulating currents on the conducting surface which reflect the circulating currents of the inductive component.

Abstract: A double tuned probe for employment in NMR apparatus includes a first resonant circuit of normal phase conductor coupled to the sample and also in communication with a second circuit containing a component in a superconductive phase. Communication between the two circuits supports two RF channels which may be exhibit relative sensitivities in proportion to their relative Q values.

Abstract: An NMR probe, lacking electrical balance in respect of the RF coil thereof, includes a conducting shield of axial extent greater than &lgr;/4 from the ground plane closure of said shield of the probe (&lgr; being the highest resonant frequency of interest), the components of the probe other than the coil being confined to the axial region less than &lgr;/4 from the ground plane and spaced apart from the shield.

Abstract: Observation of transient phenomena in an oversampled regime is implemented with a digital filter pre-charged with a list of pseudodata obtained by prepending one or more pseudo datums to the oversampled data to constitute an effective data set wherein each pseudodatum is derived from the complex conjugate of a corresponding actual datum symmetrically disposed with respect to the time origin.

Abstract: A magnetic field generated by windings supported by a cylindrical former having axis Z is established in a desired direction forming an angle &PHgr; with respect to Z. Over an interval on Z, substantially constant value for the desired field and substantially vanishing orthogonal components are achieved by specifying the current distribution on the cylinder as a solution to field equations and then approximating said current distribution in a discrete conductor forming a plurality of anharmonic loops, nonlinearly spaced in accord with said solution.

Abstract: An apparatus for tuning and/or matching a RF coil in a NMR probe comprising a first variable capacitor electrically connected to the coil and a first motor capable of coupling to the first variable capacitor. The first motor when coupled to the first capacitor adjusts a capacitance associated with the first capacitor. The first motor is capable of operating in a strong magnetic field and is capable of not disturbing homogeneity of said magnetic field when said motor is not operating. The apparatus may further include a second variable capacitor and a second motor. The first motor is further capable of coupling to the second capacitor for adjusting a capacitance associated with the second capacitor. The second motor moves the first motor between coupling with the first capacitor and coupling with the second capacitor. The mechanism may be employed to manipulate variable inductive loads for tuning and/or matching.

Abstract: A z-axis magnetic field gradient coil for nuclear magnetic resonance (NMR) spectrometry includes an etched double-sided flexible sheet having via connections running through the sheet. The vias interconnect two conductive patterns formed on opposite sides of the sheet. Each z-axis current lead is adjacent to another z-axis current lead oriented in the opposite direction, such that the z-axis current components of the two patterns cancel each other. The resulting net current component is in the x-y plane, and generates the desired z-axis magnetic field gradient.

Abstract: A gas chromatographic device has an inlet system, a column and a pressure reducing means combined and assembled in such a series arrangement that provides adequate system performance with shorter wide bore column length and shorter sample analysis times needed during a peak integration and evaluation process performed by a connected mass spectrometer system. Pressure reducing means may be integral part of the inlet system or the column when positioned between the inlet system and the column. Pressure reducing means preferably positioned before the column and being capable of reducing the pressure prevailing at the inlet of said pressure reducing means to a column outlet pressure which is essentially vacuum. Preferably, the inlet pressure of the device is in a range between 10 kPa and 1000 kPa and the absolute pressure prevailing at the outlet of said pressure reducing means is in a range between 0.00001 kPa and 50 kPa.

Abstract: An ion source for use with an ion trap mass spectrometer. The ion source includes an electron source which produces a stream of electrons. The electrons are injected into an ionization chamber by the action of a repeller plate and electron lens. Inside the ionization chamber, the electrons interact with a gas-phase sample to produce sample ions through the electron ionization process, or with a reagent gas to form reagent ions as part of a chemical ionization process. The sample ions produced are extracted from the ionization chamber by the action of an ion repeller and an ion lens. The potentials on the electron repeller and lens, and ion repeller and lens are controlled to direct the electron stream away from the ionization chamber or to direct the sample ion beam away from an ion trap at the appropriate times during measurement of the sample ions.

Abstract: An apparatus for electrospray ionization of a liquid sample matrix to prepare the sample for introduction into a mass spectrometer. The inventive electrospray interface is arranged between a source of a liquid sample matrix and an electrospray ionization needle. The interface includes a central chamber which contains elements for passively mixing the liquid sample flow with a modifying liquid added to the central chamber through a side channel. The side channel is isolated from the central chamber by a flow restrictor and the modifying liquid is provided to the side channel through a valve. A second valve, side channel, and flow restrictor are used to permit introduction of a calibration fluid into the central chamber through the first side channel. The inventive interface permits mixing of a modifying liquid with the liquid sample matrix to assist in nebulization of the liquid sample by reducing the surface tension of the sample containing fluid.

Abstract: A coil set and its design is described for obtaining a magnetic field gradient oriented at a desired angle to a uniform magnetic field wherein the coils set is disposed on a cylinder with axis along the desired gradient direction.

Abstract: A birdcage coil is globally tuned by a tuning structure to maintain constant RF phase shift for each leg conductor of the birdcage while containing a load. The birdcage coil may be globally tuned by adjusting the capacitances or inductances in a symmetrical manner.

Abstract: Spectroscopic apparatus for sequentially detecting the presence of a plurality of elements in a sample. The apparatus includes a plurality of lamps (1a-1e) each of which is for detecting the presence of a respective at least one predetermined element in a plurality of elements. A beam selector (13) which may be a mirror, is operative to direct a beam of light (7) from any one of lamps (1a-1e) to an analysis zone (8). The apparatus includes a monochromator (15), the drive (24) of which is under the control of a controller (25) with a memory device (26) linked thereto. Predetermined settings for the monochromator corresponding to the peak settings for each wavelength of interest can be stored in memory (26) for subsequently driving the monochromator to those settings without the need to undertake a peaking routine for each elemental analysis, thereby saving analyses time.

Abstract: An apparatus for producing gas-phase ions from a sample compound in a carrier liquid. The electrospray needle (or capillary) of the present invention includes a central metal tube which carries the liquid containing the sample compound. The central tube is surrounded by a plurality of tubes which transport a nebulizing gas. The nebulizing gas tubes are placed symmetrically around the outside of the liquid containing tube. The nebulizer of the present invention produces a symmetric, non-annular gas flow which has variations in pressure around the circumference of the central tube. The pressure variations of the nebulizing gas flow produce additional shear forces on the liquid emerging from the central tube. This assists in forming a uniform electrospray of droplets from the liquid at lower nebulizing gas flow rates, thereby reducing the disadvantageous effects of the higher gas flow rates used in the art.

Abstract: The present invention provides apparatus for utilizing planar HTS probe coils in substantially coplanar coil sets, each set comprised of a plurality of coils, two such similar sets being positioned on opposite sides of the sample to form a plurality of coil pairs. The coil pairs may be used for excitation of the sample, for receiving the NMR response signal or for both. A feature of the invention is the ability afforded to adjust the coupling between coil pairs to a minimum value to thereby prevent interaction between coil pairs having simultaneously applied high power signals and weak NMR response signals.

Abstract: An apparatus for efficiently removing a carrier liquid from charged liquid drops formed by electrospray ionization prior to introduction of the drops into a mass spectrometer. A central capillary tube connects a region of the low pressure vacuum system containing the mass spectrometer with a region at substantially atmospheric pressure, in which ion formation is produced by electrospray ionization. Heated, drying gas flows through a plurality of vortex forming channels symmetrically disposed about the axis of the central capillary tube which provides an entrance to the spectrometer. Gas exiting the vortex forming channels enters tangentially to the inside of a vortex drying tube with a small helix angle, causing the gas to swirl around the tube, forming a vortex. The vortex drying gas flows in a direction that is substantially transverse to the axis of the entrance capillary into the mass spectrometer.

Abstract: An improved method and apparatus are described for carrying out SPME onto the inner surface of a syringe needle at least partially coated with a stationary phase followed by desorption of analytes from a sample into a gas chromatograph injector for analysis. The SPME apparatus comprises a syringe having a syringe barrel and a plunger slidable within one end of the barrel, a hollow needle extending from the other end of the barrel and having its inner surface coated with the stationary phase, and fluid communication means for transferring a fluid into contact with the coated inner surface of said hollow needle. During the analysis phase, a carrier gas is transferred into contact with the coated inner surface. A valve means can be used to switch the flow of sample from a container containing the sample during the microextraction phase to the carrier gas during the analysis phase.

Abstract: A method and apparatus is provided for increasing sensitivity for near-real-time detection of very low concentrations of diffusely distributed trace vapors in a carrier medium. Before admitting the trace vapor bearing carrier medium into a near-real-time GC/MS trace vapor detection system, the concentration of the trace vapor in the carrier medium, air in this instance, is increased by passing it through a membrane gas separator. The gas separator preferentially passes a portion of the trace vapor and rejects all but a very small portion of the carrier medium. The sample, highly concentrated in trace vapor with respect to the carrier medium after passing through the gas separator, is then compressed by a turbomolecular pump resulting in a substantial increase in density of the trace vapor at the exhaust port of the pump and a corresponding increase in detection sensitivity.