Abstract: An optical coupling device for providing an oxygen-free optical path between a plasma torch and a monochromator includes a hollow body having means associated therewith for the venting thereof.

Abstract: A sampling valve useful in liquid chromatography includes a stationary valve member and a valve member movable with respect thereto. The movable valve member includes an axial bore having a cross-section permitting the insertion therethrough of a sample injection needle.

Abstract: A dissociation chamber and measuring cell combination which is useful for making atomic fluorescence measurements includes a heated dissociation chamber and a measuring cell separate therefrom. The combination is particularly useful for use with elements which form hydrides of the sought element.

Abstract: An apparatus for reducing the leakage current error from a resistance furnace includes a grounded electrically conductive member, an electrically insulating, thermally conductive member adjacent thereto, which thermally conductive member is contacted by a thermocouple junction.

Abstract: A phase synchronization apparatus useful for synchronizing the sample signal and the demodulation signal at a spectrometer includes a stepper motor the position of which is controlled so that the desired phase synchronization is ensured.

Abstract: Disclosed herein is method and apparatus for determining the nature of an unknown substance, which includes apparatus for entering a peak table of the spectrum of an unknown substance into computing apparatus, apparatus for adjusting the peak table to a first preselected standardized format, computing apparatus for comparing the so standardized peak table of the unknown with a first library of chemical structural units contained in memory in the computing apparatus, apparatus for making a list of the possible chemical structural units most closely corresponding to the unknown substance, apparatus for readjusting the peak table to a second preselected standardized format, apparatus for forming a file for the unknown substance including data corresponding to the readjusted peak table and to the list of possible chemical structural units, computing apparatus for comparing the file of the unknown substance with a second library containing files of known substances contained in memory in the computing apparatus, e

Abstract: In a solvent gradient liquid chromatography system, base line shift is compensated by operating the system in a calibrate cycle with a desired solvent gradient program while subtracting and recording in digital form correction factors sufficient to maintain a flat base line at timed intervals during the program, and then successively recalling said digital correction factors at corresponding time intervals during a run cycle with a test sample and converting the correction factors to analog form and subtracting the converted correction factors from the system output signal for base line correction.

Abstract: A fluid flow control device useful for liquid chromatography includes a radial distribution plate having a patterned aperture therethrough which pattern is designed to ensure that every annulus of the distribution plate having a given area has the same uniform pressure when fluid flows therethrough. The radial distribution of a fluid throughout the aperture is created by a backpressure means adjacent the downstream surface of the radial distribution plate.

Abstract: A method for coating a graphite tube for use in atomic absorption spectroscopy includes forming a layer of an adhesive volatile material on the tube. An inert material, in the form of a powder, is applied to the layer and heated to pyrolyze the inert material. Thereafter, the graphite tube is coated with pyrolytic graphite.

Abstract: A column of particulate adsorbent is located within a longitudinally extending stainless steel tube. The pollutant gas to be monitored reaches the adsorbent by molecular diffusion after passing through a diffusion gauze at the diffusion end of the tube, a stagnant diffusion zone and a partition gauze forming one longitudinal boundary of the column. In one embodiment the diffusion gauze is removably mounted in a diffusion cap that may be slid over the tube; in another, the diffusion gauze and the partition gauze are mounted in a unit which in manufacture is fitted and permanently fixed within the tube. The invention establishes that the repeatability problem in molecular diffusion personal monitors lies in the hitherto unsuspected criticality of the stagnant diffusion zone parameters and provides a general solution enabling a good compromise between repeatability and sensitivity without the need for unduly close manufacturing tolerances.

Abstract: An apparatus for controlling the temperature of a chromatography column includes a pair of base members which include means for receiving and substantially uniformly contacting the periphery of a chromatography column. Means for controlling the temperature of the column receiving means is also provided.

Abstract: A transducer for measuring extremely small rates of flow of a liquid under high pressure. A transparent tube has a small channel within which is contained a ball having a diameter substantially that of the channel. The tube is housed in a pressure vessel in such a manner that the high pressure liquid to be measured surrounds the tube over most of its length. The liquid flows externally of the tube toward the inlet end of the channel, thereby equalizing the pressure differential within and without the tube. As the fluid passes through the channel from the inlet to the outlet, it propels the ball past a sensor, such as a photoelectric device. The velocity of the ball past the sensor indicates the volumetric flow rate of the fluid. The device is periodically reset by momentarily reversing the direction of flow through the tube to return the ball to its starting position.

Abstract: A magnetic lens, useful as an objective lens in a focused charged particle beam generator, includes means for maintaining a constant thermal power dissipation independent of the field strength produced thereby.

Abstract: A spectrophotometer system has an optical system for transmitting a beam from a source at select wavelengths onto a detector. A plurality of filters are positioned in a tray. A stepper mechanism indexes the tray along a path. A microcomputer controls the stepper mechanism and the optical system. The wavelength is successively changed over a range, the tray is indexed to move a select filter into the beam at a predetermined wavelength and the changing is discontinued during indexing.

Abstract: A platen roller type printer/plotter is provided having a paper supply which is frictionally driven by the platen. The plate comprises at least three pieces which are mounted on a drive shaft with the centermost of the pieces being keyed to the shaft to rotate therewith while the other pieces of the platen are free to turn about the shaft at the same or different speeds. A paper supply is fed to the platen with a pressure roller in the middle which bears upon the central platen piece and will drive the paper straight if it is started straight. However, if the paper is put into the platen loose and skewed, driving the center platen roller pulls the paper up tight and aligns it automatically. This is due to the differential action of the different pieces of the platen since only the center piece is keyed to the shaft.An input tray which holds the paper is pivoted under the paper. Accordingly, when the paper is presented to the platen at an angle, the tray moves with the paper reducing the angle error.

Abstract: An electron multiplier, including an excitation means and collector, disposed in a high vacuum chamber and adapted to be coupled at its input to a charged particle analyzer is coupled through the vacuum chamber wall by a plurality of electrical feedthrough devices such that the excitation means is coupled to a high voltage power supply disposed outside the high vacuum chamber and the collector is coupled simultaneously through a capacitance coupling means and a resistance coupling means, both disposed within the high vacuum chamber, to an amplifier-discriminator and floating operational amplifier, respectively, both disposed outside the high vacuum chamber. The impedance offered by the capacitance coupling means is substantially lower than that offered by the resistance coupling to 10 nanosecond current pulses originating from single electron events.

Abstract: A sealing apparatus useful for sealing an injection block of gas chromatograph includes means for controlling the position of a sealing body with respect to the sealing face of such an injection block.

Abstract: A light chopper for chopping the monochromatic light beam of a spectrophotometer system, has a rotatable shaft driven by a synchronous motor at a frequency proportional to the power line frequency. An aperture bearing disc rotates with the shaft in relation to a photocell/detector array for generating digital timing signals for use by a microcomputer to control the tasks of the spectrophotometer system in synchronism with line frequency. The microcomputer monitors line frequency for responsively programming a programmable divider for generating an index signal for proportionally sequencing the wavelength of the monochromatic beam through a predetermined spectral range.

Abstract: A microprocessor based spectrophotometer including a memory system for providing storage locations of sets of operating parameters and correction data. The operator loads the memory via keyboard control. The memory system is battery backed-up for maintaining stored data during power shutdown of the spectrophotometer system.

Abstract: There is disclosed a filter-grating monochromator for use in an optical analytical instrument. The monochromator is characterized by a simplified construction compared to prior art monochromators. Nevertheless, the monochromator includes features which retain the desired high accuracy, including a novel sine bar grating drive mechanism and filter change mechanism.