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: 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: 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 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: 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: 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: 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: 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.

Abstract: An explosive and narcotics detection system detects the presence of trace particles of materials that are adhering to surfaces. In order to detect such particles, to the particles are first dislodged or released from the surface, then transported to the detection instrument, and then accumulated on or in a particle collection device. When the sample collecting system and the target surface are in relative motion across the line-of-sight greater than fifteen centimeters per second, non-contact sample collection may be accomplished using a vortex or vortex attractor particle collector together with a plurality of air or aerosol jets. A plurality of large diameter vortex collectors may obtain samples at relative line-of-sight velocities greater than five feet per second over a large surface area and for a complex-shaped surface.

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: Vapor concentrators are used to provide a higher concentration of trace target vapor than would normally be available in the environment. This is accomplished by allowing the trace target vapor to adsorb onto a concentrating surface and subsequently releasing the trace target vapor by heating the surface. An improved desorbing method is providing by a fast pulse of photons, which only heats the near surface region, rather than the entire mass of the substrate on which the concentrating surface resides. Since all of the trace target vapor is released in a short time interval, the vapor is less diluted by carrier gas than would occur during the slower temperature ramp that results when the entire substrate mass is heated. A more highly concentrated target vapor is produced with less input of energy.

Abstract: The presence of trace molecules in air is often determined using high sensitivity gas sensing instruments, such as an ion mobility spectrometer. Such devices are commonly utilized in the fields of explosives detection, identification of narcotics, and in applications characterized by the presence of very low airborne concentrations of organic molecules of special interest. The sensitivity of such instruments is dependent on the concentration of target gas in the sample. The sampling efficiency can be greatly improved when the target object is warmed, even by only a few degrees. A directed emission of photons in the range between infrared and ultraviolet light can be used to significantly enhance vapor emission.

Abstract: The presence of trace molecules in air may be determined using an ion mobility spectrometer. Such devices may be used in the fields of explosives detection, identification of narcotics, and in applications characterized by the presence of very low airborne concentrations of organic molecules of special interest. The sensitivity of such instruments may depend upon on the method of gas sampling utilized. A virtual wall gas sampling system can greatly improve the sampling efficiency, particularly when the sampling needs to be performed at a distance from the air intake and large volumes need to be sampled. The virtual wall gas sampling system consists of an intake gas flow and a separate group of one or more sheet-like gas flows, which may be either mutually deflected to move with a circular motion or may be formed into a cylindrical bounding surface.

Abstract: The presence of trace molecules in air is often determined using a well-known device called an ion mobility spectrometer. Such devices are commonly utilized in the fields of explosives detection, identification of narcotics, and in applications characterized by the presence of very low airborne concentrations of organic molecules of special interest. The sensitivity of such instruments is dependent on the method of gas sampling utilized. The vortex sampling nozzle consists of an intake gas flow and a separate coaxial heated, emitted gas flow that is deflected to move with a circular motion. A heated vortex sampling nozzle can greatly improve the sampling efficiency for low volatility target molecules, particularly when the sampling needs to be performed at a distance from the air intake and the vapor pressure of the target molecules is very low.

Abstract: The presence of trace molecules in air may be determined using an ion mobility spectrometer. Such devices may be used in the fields of explosives detection, identification of narcotics, and in applications characterized by the presence of very low airborne concentrations of organic molecules of special interest. The sensitivity of such instruments is dependent on the method of gas sampling utilized. A cyclone sampling nozzle can greatly improve the sampling efficiency, particularly when the sampling needs to be performed at a distance from the air intake. The cyclone sampling nozzle consists of an intake gas flow and a separate coaxial emitted gas flow which is deflected to move with a circular motion.

Abstract: Vapor concentrators are used to provide a higher concentration of trace target vapor than would normally be available in the environment. This is accomplished by allowing the trace target vapor to adsorb onto a concentrating surface and subsequently releasing the trace target vapor by heating the surface. An improved desorbing method is providing by a fast pulse of photons, which only heats the near surface region, rather than the entire mass of the substrate on which the concentrating surface resides. Since all of the trace target vapor is released in a short time interval, the vapor is less diluted by carrier gas than would occur during the slower temperature ramp that results when the entire substrate mass is heated. A more highly concentrated target vapor is produced with less input of energy.