Abstract: A molecular spectrometer is provided that performs Fourier analysis utilizing the discrete Fourier Transform on a digitized time domain waveform that relates to the composition of a sample. Digitized reference waveforms are employed to permit the instrument to limit its analysis to frequencies of interest and thereby increase the rapidity of the analysis. Data at differing frequencies can be resolved at independent resolutions, and the instrument can analyze spectroscopic data in real time.

Abstract: A monitoring circuit monitors a piezoelectric crystal for changes in its resonant frequency as a film of material is vacuum deposited on it, e.g. to control a source of vapors of the material. A controllable frequency generator generates a drive signal of a accurately known frequency and phase within a band of RF frequencies that includes the resonant frequency of the crystal. The RF signal is applied through a duplexing circuit to the crystal, and a response signal is applied through the duplexing circuit to a signal amplifier and limiter circuit to a phase detector. The phase detector is also supplied with the RF drive signal, and has a phase output signal which is zero when the crystal is at resonance, and is negative or positive when the applied RF signal is below or above resonance, respectively.

Abstract: The thickness and rate of growth of a deposited film is monitored using a piezoelectric crystal sensor such as an AT-cut plano-convex crystal. The frequencies of the fundamental frequency and another resonance mode are measured prior to deposition, and the change of these two frequencies is monitored during deposition. The areal mass density of the deposited material is determined from these two resonance frequencies for the uncoated quartz crystal and for the crystal during deposition. A frequency generator provides accurate sweeps of frequency which are applied to the crystal, and the crystal response is supplied to a phase detector to identify the positions of the resonance frequencies. The acoustic impedance ratio Z of the deposited material relative to the fresh crystal is computed from the resonance frequencies for the coated and uncoated crystal, by applying the modal equations for AT-cut plano-convex quartz crystal and Lu-Lewis relation.

Abstract: A sensor for selectively sensing the presence of halogenated gases, particularly HFC's, within an atmosphere. The apparatus includes a ceramic element containing either a mixture of alkali metal silicates and aluminum oxide or aluminosilicate which react with ions of the halogenated gas when the two are brought together forming a depletion layer on and within the ceramic. A preferred ceramic composition is a mixture of potassium slicate and either one of silicon dioxide or aluminum oxide. The sensor is formed with two electrodes on opposite sides of the ceramic having terminals connected into a circuit for detecting a potential difference across the depletion layer. Means are provided for detecting the potential differences and for producing a discernable signal in response thereto.

Abstract: A multiple crystal head has aluminum rotary carousel within an aluminum body, and number of crystals disposed about the axis of the carousel. A water line coil is clamped to the aluminum body by a stainless steel clamp plate, and a beryllium copper finger spring provides thermal contact between the carousel and the body so that any heat from the deposition process is quickly removed by the water coil. A space is maintained between the front of the carousel and the proximal side of the body front face so that there is no scraping when the carousel rotates. A removable stainless steel heat shield over the body provides good thermal isolation and prevents deposits from reaching the aluminum body or other parts behind the shield. A pneumatic bellows and a pawl and ratchet assembly rotate the carousel to bring the various crystals into the active, monitoring position.

Abstract: An optical partical pressure gas analyzer employs an electron beam to excite the outer electrons of gas atoms or molecules, and one or more photomultiplier tubes or other similar detectors to detect wavelengths of photons characteristic of the decay of the outer electrons of one or more species of gas molecules. The photomultiplier tubes have a viewing direction substantially at right angles to the electron beam. A Faraday trap or similar device is employed to minimize secondary electron generation. This-film interference filters are favorably employed to pass a specific characteristic wavelength of the desired species, and to reject other wavelengths. An electromechanical filter changer permits each photomultiplier tube to analyze and identify many gaseous species in the low pressure mixture.

Abstract: Ion detection apparatus has an ionizer provided with an ionizer volume for receiving a specimen to be analyzed. An electron gun is operatively associated with the ionizer for bombarding the specimen with an electron beam and converting the specimen into ions. An analyzer receives the ions from the ionizer volume and includes a detector for detecting the ions. The electron gun has focusing means for varying the size and intensity of the electron beam. The electron gun may have an accelerating anode, a focusing collimator and a second anode. The ionizer means may have an extractor lens and collimating lens as well as a groundplate. The ionizer means may have an electron collecting plate for receiving electrons which pass through the ionizer volume and providing feedback regarding the electron beam.