Abstract: A gas sensor includes a first chamber containing a plurality of evenly spaced rods having voltages applied thereto to cause gas ions in the first chamber to move in a direction from a first end of the first chamber to a second end of the first chamber and a second chamber coupled to the second end of the first chamber and having at least one ion detector, where ions pass from the first chamber to the second chamber through a plurality of channels between the first chamber and the second chamber and are detected by the at least one ion detector. The voltages applied to the rods may include a first voltage applied to a first subset of the rods and a second voltage applied to a second subset of the rods, each of first and second voltages containing a DC component and an AC component.

Abstract: A tandem instrument using a variable frequency pulsed ionization source and two separation techniques, low (IMS) and high (FAIMS) field mobility is provided. The analytical stage features a field driven FAIMS cell embedded on-axis within the IMS drift tube. The FAIMS cell includes two parallel grids of approximately the same diameter as the IMS rings and can be placed anywhere along the drift tube and biased according to their location in the voltage divider ladder to create the same IMS field. The spacing between the grids constitutes the analytical gap where ions are subject, in addition to the drift field, to the asymmetric dispersive field of the FAIMS. The oscillatory motion performed during the high and low voltages of the asymmetric waveform separates the ions according to the difference in their mobilities.

Abstract: Devices and techniques for ion analysis, including ion mobility separation and mass spectrometry, are provided using a dual polarity spark ion source and having the flexibility required to optimize the detection performance for a broad range of illicit substances with different physical and chemical properties. In various embodiments, the volatility and electro-chemical aspects may be addressed by the system described herein by performing real-time detection of compounds detectable in both positive and negative polarities and/or prioritizing spectra acquisition in a given polarity due to the high volatility and therefore short residence of certain target compounds.

Abstract: For ion mobility spectrometry applications, a desired shape of a sensor structure may be created by forming a desired shape from a ceramic material, such as aluminum nitride. In various embodiments, the sensor structure may be formed using discrete individual ceramic sheets and/or from a preformed ceramic tube. Via holes are formed into the sensor structure to provide for efficient circuitry configurations of the IMS drift tube and/or providing electrical connections between the interior and exterior of the drift tube.

Abstract: Using combined orthogonal techniques, such as low (IMS) and high (FAIMS) field mobility techniques, offers several advantages to ion detection and analysis techniques including low cost, no vacuum required, and the generation of 2-D spectra for enhanced detection and identification. Two analytical devices may be operated in different modes, which results in overall flexibility by adapting the hyphenated instrument to the application's requirements. With the IMS-FAIMS hardware level flexibility, the instruments may be configured and optimized to exploit different trade-offs suitable for a variety of detection scenarios of for different lists of target compounds.

Abstract: Selective ionization at atmospheric or near atmospheric pressure of a sample diluted in air is provided in multiple steps. Initially, components of air and/or other gas are ionized to generate reactive ions. The reactive ions are then filtered using a high frequency filter to yield selected reactive ions. Thereafter, the selected reactive ions are reacted with sample molecules of a sample being analyzed in a charge transfer process. Depending on the properties of the sample molecules, the filter may select some reactive ions to enter the sample zone and block others entirely thus controlling ion chemistry and charge transfer yields in the sample zone. The described system is directed to controlling ions at the ion source level, using a high frequency filter technique, in connection with subsequent analysis. The method generates the ions of choice for subsequent analysis in such platforms as ion mobility and differential mobility spectrometers.

Abstract: An explosive and narcotics detection system detects the presence of trace particles of those materials that are adhering to surfaces. In order to detect such particles, it is necessary to first dislodge or release them from the surface, next to transport them to the detection instrument, and last to accumulate them on or in a particle collection device associated with the instrument. Narcotics and explosive particles are often bound tenaciously to the surface, and simple techniques, such as blowing air, will either remove only the largest particles or none at all. A nozzle to release particles of narcotics and explosives employs a coaxial configuration that permits particle release at an increased distance from the nozzle compared to existing devices.

Abstract: A system and method for producing a continuous or pulsed source of high energy electrons at or near atmospheric pressure is disclosed. High energy electrons are used to ionize analyte molecules in ambient air through collisions with reactant ions. The device includes an electron emitter, electron optics, and a thin membrane in an evacuated tube. The electron emitter may include a photocathode surface mounted on an optically transparent window and an external source of UV photons. The transparent window may include a UV transparent window mounted on an evacuated tube and/or the evacuated tube may be a transparent tube on which a photocathode surface film is deposited. The electron optics may include successive electrodes biased at increasing voltages. The membrane may include a material transparent or semi-transparent to energetic electrons. Upon impacting the membrane, continuous or pulsed electron packets are partially transmitted through to a high pressure ionization region.

Abstract: For ion mobility spectrometry applications, a desired shape of a sensor structure may be created by forming a desired shape from a ceramic material, such as aluminum nitride. In various embodiments, the sensor structure may be formed using discrete individual ceramic sheets and/or from a preformed ceramic tube. Via holes are formed into the sensor structure to provide for efficient circuitry configurations of the IMS drift tube and/or providing electrical connections between the interior and exterior of the drift tube.

Abstract: A system and method for producing a continuous or pulsed source of high energy electrons at or near atmospheric pressure is disclosed. High energy electrons are used to ionize analyte molecules in ambient air through collisions with reactant ions. The device includes an electron emitter, electron optics, and a thin membrane in an evacuated tube. The electron emitter may include a photocathode surface mounted on an optically transparent window and an external source of UV photons. The transparent window may include a UV transparent window mounted on an evacuated tube and/or the evacuated tube may be a transparent tube on which a photocathode surface film is deposited. The electron optics may include successive electrodes biased at increasing voltages. The membrane may include a material transparent or semi-transparent to energetic electrons. Upon impacting the membrane, continuous or pulsed electron packets are partially transmitted through to a high pressure ionization region.

Abstract: An explosive and narcotics detection system detects the presence of trace particles of those materials that are adhering to surfaces. In order to detect such particles, it is necessary to first dislodge or release them from the surface, next to transport them to the detection instrument, and last to accumulate them on or in a particle collection device associated with the instrument. Narcotics and explosive particles are often bound tenaciously to the surface, and simple techniques, such as blowing air, will either remove only the largest particles or none at all. A nozzle to release particles of narcotics and explosives employs a coaxial configuration that permits particle release at an increased distance from the nozzle compared to existing devices.

Abstract: Selective ionization at atmospheric or near atmospheric pressure of a sample diluted in air is provided in multiple steps. Initially, components of air and/or other gas are ionized to generate reactive ions. The reactive ions are then filtered using a high frequency filter to yield selected reactive ions. Thereafter, the selected reactive ions are reacted with sample molecules of a sample being analyzed in a charge transfer process. Depending on the properties of the sample molecules, the filter may select some reactive ions to enter the sample zone and block others entirely thus controlling ion chemistry and charge transfer yields in the sample zone. The described system is directed to controlling ions at the ion source level, using a high frequency filter technique, in connection with subsequent analysis. The method generates the ions of choice for subsequent analysis in such platforms as ion mobility and differential mobility spectrometers.

Abstract: An explosive and narcotics detection system detects the presence of trace particles of those materials that are adhering to surfaces. In order to detect such particles, it is necessary to first dislodge or release them from the surface, next to transport them to the detection instrument, and last to accumulate them on or in a particle collection device associated with the instrument. Narcotics and explosive particles are often bound tenaciously to the surface, and simple techniques, such as blowing air, will either remove only the largest particles or none at all. A nozzle to release particles of narcotics and explosives employs a coaxial configuration that permits particle release at an increased distance from the nozzle compared to existing devices.

Abstract: A trace particle collection system accumulates trace particles of those materials that are adhering to target surfaces. The particles are removed from the surface, transported and collected in a particle collection medium, and then provided to a detection instrument. Trace particles are often bound tenaciously to the target surface, and simple techniques, such as blowing air, will either remove only the largest particles or none at all. The removal of trace particles is described which utilizes an aerosol mixture of frozen carbon dioxide aerosol particles in a gas stream to impact and more efficiently remove the target particles from the surface.

Abstract: A trace detection system includes at least two stages coupled to operate in series. An ion mobility spectrometer (IMS) stage has a sampling inlet to receive a sample to be analyzed. An ion source ionizes the sample. The IMS applies an electrical field to the ionized sample to move the ionized sample toward an IMS outlet. A differential mobility spectrometer (DMS) stage coupled in series with the IMS stage receives the ionized sample from the IMS stage. Preferably, the system includes a mass spectrometer (MS) stage coupled in series with the DMS stage to receive the ionized sample from the DMS stage via a vacuum interface. A roughing vacuum pump evacuates a first stage of the MS stage to a first pressure below atmospheric pressure. A high vacuum pump evacuates a second stage of the MS stage to a second pressure below the first pressure.

Abstract: An explosive and narcotics detection system detects the presence of trace particles of those materials that are adhering to surfaces. The particles are removed from the surface, transported and collected in a particle collection medium, and then provided to detection instrument. Narcotics and explosive particles are often bound tenaciously to the surface, and simple techniques, such as blowing air, will either remove only the largest particles or none at all. Techniques for the removal of narcotics and explosives particles are described which utilize an aerosol mixture of aerosol particles in a gas stream to impact and more efficiently remove the target narcotics and explosives particles from the surface.

Abstract: A chemical sample gas tube that is capable of being rapidly heated and cooled allows rapid purging of condensed chemical vapor from its inside surface. The tube may include a thin foil with an electrically conducting surface, a rigidly separated pair of clamps to shape the thin foil into a cylinder shape, and a temperature-controlled source of electricity that can flow sequentially through the clamps and thin foil for heating. The temperature of the cylindrical thin foil may be increased at a rate of at least 25 degrees Celsius per second, and may be cooled at a rate of at least 10 degrees Celsius per second. A temperature control sequence may be provided that includes at least one temperature that performs at least one of: condensing the chemical vapor, transmitting the chemical vapor, desorbing the condensed chemical vapor, and decomposing the condensed chemical vapor.

Abstract: A system and method for providing a pulsed atmospheric source of ions for chemical analysis includes a chamber containing a pair of electrodes and a second chamber with the sample gas. A narrow pulse of high voltage is applied between the electrodes to form an arc which emits ultraviolet light directly into the sample gas chamber through an aperture connecting the chambers. The ultraviolet photons ionize the sample gas and the resultant sample gas ions are then swept into a chemical detector by an electric field.

Abstract: An explosive and narcotics detection system using an ion mobility spectrometer detects the presence of vapor or trace particles of target chemicals. The calibration of the spectrometer depends in part on the stability of a calibrant chemical that may be periodically injected together with sample gas into the ionization region of the spectrometer. The calibrant chemical produces a signal with a drift time that is known relative to target chemicals and may be used to calibrate the expected target chemical drift times. A new calibrant chemical, 5-nitrovanillin, is disclosed for this purpose.

Abstract: An explosive detection system based on an ion mobility spectrometer detects the presence of trace molecules in air. Such instruments require an ion source to ionize the trace molecules. An ion source that does not require a radioactive source to operate can use the photoelectric effect to produce electrons. Such a photoelectric ion source will gradually be contaminated and lose its photoelectron emission properties when operated in the air. The photocathode of the ion source can be automatically regenerated by a heater in thermal communication with the photocathode. The heater may be activated when the photoelectron emission falls below a predetermined value ro may run or cycle continuously.