Abstract: A novel filter effectiveness detection method for AMCs (Airborne Molecular Contaminations) is provided herein, which is on-line, economical and applicable for diverse AMCs, using gas-to-particle conversion with soft X-ray irradiation radiation. In one embodiment, this method was conducted through AMC filter evaluations comparing two granular activated carbons (GACs), which are widely used AMC filter media, challenged with sulfur dioxide (SO2), which is one of the major known AMCs in cleanrooms. Using this method, the concentration of gaseous SO2 was assessed in terms of particle volume concentrations after the gas-to-particle conversion assisted by the soft X-ray irradiation. The results of this detection method showed high sensitivity to SO2, down to parts per trillion-levels, which are levels that are too low to be detectable by currently available commercial gas sensors.

Abstract: Methods and apparatuses for the removal, analysis and/or detection of harmful airborne molecular contaminants (AMCs). In one embodiment, an ionizing radiation source is utilized to remove the harmful AMCs from a flow stream via radiolytic particle generation and subsequent capture by filtration. The captured particles may be released, for example, by re-gasification for analysis at much higher concentrations. In another embodiment, the ionizing radiation source is utilized with a particle detector to sense when harmful AMCs are present. In one embodiment, a solid optical medium is exposed to a monitored environment so that the AMCs are in contact with a surface of the solid optical medium. A focused light beam is arranged to emerge from a solid optical medium at an energy density sufficient to cause the AMCs to form deposits on the exposed surface of the solid optical medium, which can be detected using an interferometric technique.

Abstract: A novel filter effectiveness detection method for AMCs (Airborne Molecular Contaminations) is provided herein, which is on-line, economical and applicable for diverse AMCs, using gas-to-particle conversion with soft X-ray irradiation radiation. In one embodiment, this method was conducted through AMC filter evaluations comparing two granular activated carbons (GACs), which are widely used AMC filter media, challenged with sulfur dioxide (SO2), which is one of the major known AMCs in cleanrooms. Using this method, the concentration of gaseous SO2 was assessed in terms of particle volume concentrations after the gas-to-particle conversion assisted by the soft X-ray irradiation. The results of this detection method showed high sensitivity to SO2, down to parts per trillion-levels, which are levels that are too low to be detectable by currently available commercial gas sensors.

Abstract: Methods and apparatuses for the removal, analysis and/or detection of harmful airborne molecular contaminants (AMCs). In one embodiment, an ionizing radiation source is utilized to remove the harmful AMCs from a flow stream via radiolytic particle generation and subsequent capture by filtration. The captured particles may be released, for example, by re-gasification for analysis at much higher concentrations. In another embodiment, the ionizing radiation source is utilized with a particle detector to sense when harmful AMCs are present. In one embodiment, a solid optical medium is exposed to a monitored environment so that the AMCs are in contact with a surface of the solid optical medium. A focused light beam is arranged to emerge from a solid optical medium at an energy density sufficient to cause the AMCs to form deposits on the exposed surface of the solid optical medium, which can be detected using an interferometric technique.

Abstract: A respirator leak detection system and method for increasing the sensitivity and accuracy of leak detection through the fit seal of a respirator. A charged particle separator is used to separate charged particles that pass therethrough and to draw charged particles away from an aerosol flow into a clean gas flow. The separator may also be configured as an aerosol concentrator that takes in a major aerosol flow and outputs a minor flow of higher particle concentration. Neutral particles having no charge, which may have passed through the filtering medium respirator and which are not indicative of fit seal leaks are not entrained in the output flow for subsequent detection, thus increasing the accuracy of the filter leak detection system.

Abstract: An instrument for non-invasively measuring nanoparticle exposure includes a corona discharge element generating ions to effect unipolar diffusion charging of an aerosol, followed by an ion trap for removing excess ions and a portion of the charged particles with electrical mobilities above a threshold. Downstream, an electrically conductive HEPA filter or other collecting element accumulates the charged particles and provides the resultant current to an electrometer amplifier. The instrument is tunable to alter the electrometer amplifier output toward closer correspondence with a selected function describing particle behavior, e.g. nanoparticle deposition in a selected region of the respiratory system. Tuning entails adjusting voltages applied to one or more of the ion trap, the corona discharge element and the collecting element. Alternatively, tuning involves adjusting the aerosol flow rate, either directly or in comparison to the flow rate of a gas conducting the ions toward merger with the aerosol.

Abstract: An attenuated soft x-ray neutralizer for neutralizing aerosols. The apparatus includes a soft x-ray emitter that emits soft x-rays into an aerosol conditioning chamber. An attenuating window may be included that reduces the intensity of the soft x-rays that bombard the aerosol, thus generating fewer radiolytically generated particles. Another way to reduce or control the intensity of the soft x-rays is to control emission of the cathode in the soft x-ray emitter. The reduced intensity of the soft x-rays was found by experiment to satisfactorily condition an aerosol stream without substantial radiolytic generation of particles precipitation.

Abstract: A system is disclosed for condensation particle counting in conjunction with modifying an aerosol to enhance the formation and growth of droplets of a selected working fluid, preferably water. Before saturation with the working fluid, the aerosol is exposed to an aerosol modifying component, preferably a vapor including molecules that are adsorbed onto surfaces of the particles or other elements suspended in the aerosol. Adsorption alters the surface character of the suspended elements towards increased affinity for the vapor of the working fluid, to promote the formation and growth of working fluid droplets. The droplets are optically detected to indicate numbers and concentrations of the suspended elements.

Abstract: Particle analyzing systems with fluorescence detection are disclosed, primarily in connection with particle sizing based on scattered light intensity or time-of-flight measurement. In one system, emission of fluorescence is used as a threshold for selecting particles for further analysis, e.g. mass spectrometry. In another embodiment, laser beams arranged sequentially along an aerosol path are selectively switched on and off, to increase the useful life of components, and diminish the potential for interference among several signals. Other embodiments advantageously employ color discrimination in aerodynamic particle sizing, single detectors positioned to sense both scattered and emitted fluorescent radiation, and laser beam amplitude or gain control to enhance the range of fluorescence detection.

Abstract: Particle analyzing systems with fluorescence detection are disclosed, primarily in connection with particle sizing based on scattered light intensity or time-of-flight measurement. In one system, emission of fluorescence is used as a threshold for selecting particles for further analysis, e.g. mass spectrometry. In another embodiment, laser beams arranged sequentially along an aerosol path are selectively switched on and off, to increase the useful life of components, and diminish the potential for interference among several signals. Other embodiments advantageously employ color discrimination in aerodynamic particle sizing, single detectors positioned to sense both scattered and emitted fluorescent radiation, and laser beam amplitude or gain control to enhance the range of fluorescence detection.

Abstract: A system for analyzing aerosols incorporates a corona discharge ion generator with a positively or negatively charged corona discharge needle formed of platinum or a platinum alloy. A high speed (40-210 meter per second) air flow sweeps the ions away from the corona discharge, and propels the ions into a mixing chamber in a turbulent jet that encounters an aerosol, also provided to the mixing chamber. In one version of the ion generator, the ions are carried into the mixing chamber through an orifice formed in a positively or negatively biased plate. In another alternative, the aerosol droplets are electrostatically generated, and propelled into the mixing chamber as an aerosol jet that confronts the ion jet to enhance a mixing of the charged droplets and the ions. In this version the droplets are advantageously neutralized to leave predominantly singly charged positive and negative particles, to provide a neutralized aerosol particularly well suited for analysis with a mass spectrometer.

Abstract: An aerosol detector, particularly well suited for liquid chromatography applications, includes a corona discharge source controlled to selectively charge the non-volatile residue particles of an aerosol. The aerosol initially is composed of droplets of a liquid sample, with the residue particles resulting from droplet evaporation. The selectively charged residue particles, each carrying a charge in proportion to its size, are collected at a conductive filter. The electrical current along a conductor coupled to the filter is measured repeatedly or continuously to provide an indication of concentrations of the non-volatile material. Preferably, a pneumatic nebulizer is used to generate the aerosol. When used in a liquid chromatography system, the detector can yield several separated areas of relatively high electrical current, corresponding to concentrations of several different analytes in the liquid sample.

Abstract: A system for analyzing aerosols incorporates a corona discharge ion generator with a positively or negatively charged corona discharge needle formed of platinum or a platinum alloy. A high speed (40-210 meter per second) air flow sweeps the ions away from the corona discharge, and propels the ions into a mixing chamber in a turbulent jet that encounters an aerosol, also provided to the mixing chamber. In one version of the ion generator, the ions are carried into the mixing chamber through an orifice formed in a positively or negatively biased plate. In another alternative, the aerosol droplets are electrostatically generated, and propelled into the mixing chamber as an aerosol jet that confronts the ion jet to enhance a mixing of the charged droplets and the ions. In this version the droplets are advantageously neutralized to leave predominantly singly charged positive and negative particles, to provide a neutralized aerosol particularly well suited for analysis with a mass spectrometer.

Abstract: An aerosol detector, particularly well suited for liquid chromatography applications, includes a corona discharge source controlled to selectively charge the non-volatile residue particles of an aerosol. The aerosol initially is composed of droplets of a liquid sample, with the residue particles resulting from droplet evaporation. The selectively charged residue particles, each carrying a charge in proportion to its size, are collected at a conductive filter. The electrical current along a conductor coupled to the filter is measured repeatedly or continuously to provide an indication of concentrations of the non-volatile material. Preferably, a pneumatic nebulizer is used to generate the aerosol. When used in a liquid chromatography system, the detector can yield several separated areas of relatively high electrical current, corresponding to concentrations of several different analytes in the liquid sample.

Abstract: An electrospray nebulizer generates an aerosol comprised of submicrometer droplets substantially uniform in size. A liquid sample is supplied at a controlled rate to a capillary needle of the nebulizer, and droplets are formed due to an electrical field in the region about the needle discharge. The tendency of the droplets to disintegrate due to Coulomb forces is counteracted by sources of ionizing radiation within the nebulizer. The ions reduce the charge in each droplet while solvent evaporation reduces the diameter of the droplet. To further ensure against Coulomb disintegration, a controlled air sheath is introduced to the nebulizer for transporting droplets more rapidly downstream. Optionally, solvent vapor can be introduced into the air flow to reduce the rate of solvent evaporation within the nebulizer, and ions can be added to the air flow upstream of the needle discharge.

Abstract: A particle flux counter apparatus utilizing light extinction. The apparatus utilizes two oppositely disposed cylindrical mirrors (21a, 21b) to bounce a beam back and forth between them, the beam traversing the length of the cylindrical mirrors (21a, 21b) in incremental steps. A plane mirror (22) is cooperatively located to reflect the beam back between the system to traverse the length of the cylindrical mirrors (21a, 21b) a second time in incremented steps. The two sets of steps interleaving such that the beam forms a sheet of light. A detector (60) monitors the intensity of the beam. As particles in a sample aerosol intersect the beam, the light is extinguished and the beam intensity changes. The detector (60) transmits a signal to a microprocessor (108) analyzation. The apparatus also utilizes a feedback circuit (300) to regulate the beam intensity and alternatively provides for modulating the beam to provide for higher peak power into the detector (60) and elimination of common mode noise.

Abstract: An apparatus and method for determining the concentration of macromolecules and colloids in a liquid sample is disclosed. The apparatus preferably includes an electrospray apparatus 16 for forming droplets from the sample. Liquid is removed from the droplets by drying in the electrospray apparatus 16, thereby forming an aerosol. The aerosol of a size greater than a predetermined size is then counted by a condensation nucleus counter 52. In this manner, the target macromolecules and colloids are counted. This apparatus is capable of detecting very small macromolecules and colloids of a wide range of materials in a liquid, for example, individual molecules having molecular weight as small as 10,000.

Abstract: Methods and apparatus for enhancing the accuracy of laser optical measuring instruments using fringe pattern spacing are disclosed. The apparatus in one embodiment includes a laser beam source 10, a beam splitter 14, and mirrors 22 to deflect the beams 18, 20 emitted from the beam splitter 14 to a sensing volume. Alternative embodiments include prisms 42, 44, gratings 62 or other optical devices in lieu of mirrors 22. Objects passing through the sensing volume scatter light which is detected by the instrument to determine, among other things, the velocity of the object. The emitted beams 18, 20 are automatically deflected in response to wavelength changes of the laser beam 16 such that variations in the fringe spacing, due to variations in laser beam 16 wavelength, are compensated by variations in the closing angle K of the emitted, deflected beams. The fringe pattern spacing is thereby held more nearly constant enhancing the accuracy of the instrument.