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: A system and method for making nanoparticles. The system includes a first cathode including a first metal tube associated with a first end and a second end, a first anode including a second metal tube associated with a third end and a fourth end, and a first container including a first gas inlet. The first end and the third end are located inside the first container. The first end and the third end are separated by a first gap, the first metal tube is configured to allow a first gas to flow from the second end to the first end, and the first container is configured to allow a second gas to flow from the first gas inlet into the second metal tube through at least a first part of the first gap.

Abstract: A method, system, apparatus, and article of manufacture provide a cross-flow migration classifier capable of separating particles. The classifier provides a channel through which a sample, having one or more particles, passes in a first direction, wherein the channel comprises two or more walls that are permeable to a flow of fluid. A cross-flow enters the channel through one of the permeable walls and exits through another of the permeable walls. An imposed field is applied in a second direction that is counter to the cross-flow and having an orthogonal component to the first direction. The imposed field causes one or more of the particles to migrate at a first velocity opposite and/or equal to a second velocity of the cross-flow. The particles that migrate opposite to the cross-flow are continuously discharged from the cross-flow migration classifier.

Abstract: A process for forming an aerosol of semiconductor nanoparticles includes pyrolyzing a semiconductor material-containing gas then quenching the gas being pyrolyzed to control particle size and prevent uncontrolled coagulation. The aerosol is heated to densify the particles and form crystalline nanoparticles. In an exemplary embodiment, the crystalline particles are advantageously classified by size using a differential mobility analyzer and particles having diameters outside of a pre-selected range of sizes, are removed from the aerosol. In an exemplary embodiment, the crystalline, classified and densified nanoparticles are oxidized to form a continuous oxide shell over the semiconductor core of the particles. The cores include a density which approaches the bulk density of the pure material of which the cores are composed and the majority of the particle cores are single crystalline. The oxidized particles are deposited on a substrate using thermophoretic, electrophoretic, or other deposition means.

Abstract: A method, system, apparatus, and article of manufacture provide a cross-flow migration classifier capable of separating particles. The classifier provides a channel through which a sample, having one or more particles, passes in a first direction, wherein the channel comprises two or more walls that are permeable to a flow of fluid. A cross-flow enters the channel through one of the permeable walls and exits through another of the permeable walls. An imposed field is applied in a second direction that is counter to the cross-flow and having an orthogonal component to the first direction. The imposed field causes one or more of the particles to migrate at a first velocity opposite and/or equal to a second velocity of the cross-flow. The particles that migrate opposite to the cross-flow are continuously discharged from the cross-flow migration classifier.

Abstract: A stratum or discontinuous monolayer of dielectric-coated semiconductor particles includes a high density of semiconductor nanoparticles with a tightly controlled range of particle sizes in the nanometer range. In an exemplary embodiment, the nanoparticles of the stratum are substantially the same size and include cores which are crystalline, preferably single crystalline, and include a density which is approximately the same as the bulk density of the semiconductor material of which the particle cores are formed. In an exemplary embodiment, the cores and particles are preferably spherical in shape. The stratum is characterized by a uniform particle density on the order of 1012 to 1013 particles/cm2. A plurality of adjacent particles contact each other, but the dielectric shells provide electrical isolation and prevent lateral conduction between the particles of the stratum. The stratum includes a density of foreign atom contamination of less than 1011 atoms/cm2.

Abstract: A fast mixing condensation nucleus counter useful for detecting particles entrained in a sample gas stream is provided. The fast mixing condensation nucleus counter comprises a detector and a mixing condensation device having a mixing chamber adapted to allow gas to flow from an inlet to an outlet, wherein the outlet directs the gas flow to the detector. The mixing chamber has an inlet for introducing vapor-laden gas into the chamber and at least one nozzle for introducing a sample gas having particles entrained therein into the chamber. The inlet and nozzle are arranged such that the vapor-laden gas and sample gas mix turbulently. The mixing chamber is configured such that the particles flow through the mixing chamber at a substantially uniform relative velocity.

Abstract: A cloud condensation nucleus spectrometer having a streamwise segmented condensation nucleus growth column. The condensation nucleus growth column includes alternating hot and cold temperature-maintaining segments arranged next to one another. The temperature difference between adjacent hot and cold temperature-maintaining segments increases from the input opening to an output opening of the condensation nucleus growth column to produce a supersaturation distribution that increases from the input opening to the output opening.

Abstract: A process for forming an aerosol of semiconductor nanoparticles includes pyrolyzing a semiconductor material-containing gas then quenching the gas being pyrolyzed to control particle size and prevent uncontrolled coagulation. The aerosol is heated to densify the particles and form crystalline nanoparticles. In an exemplary embodiment, the crystalline particles are advantageously classified by size using a differential mobility analyzer and particles having diameters outside of a pre-selected range of sizes, are removed from the aerosol. In an exemplary embodiment, the crystalline, classified and densified nanoparticles are oxidized to form a continuous oxide shell over the semiconductor core of the particles. The cores include a density which approaches the bulk density of the pure material of which the cores are composed and the majority of the particle cores are single crystalline. The oxidized particles are deposited on a substrate using thermophoretic, electrophoretic, or other deposition means.

Abstract: A stratum or discontinuous monolayer of dielectric-coated semiconductor particles includes a high density of semiconductor nanoparticles with a tightly controlled range of particle sizes in the nanometer range. In an exemplary embodiment, the nanoparticles of the stratum are substantially the same size and include cores which are crystalline, preferably single crystalline, and include a density which is approximately the same as the bulk density of the semiconductor material of which the particle cores are formed. In an exemplary embodiment, the cores and particles are preferably spherical in shape. The stratum is characterized by a uniform particle density on the order of 1012 to 1013 particles/cm2. A plurality of adjacent particles contact each other, but the dielectric shells provide electrical isolation and prevent lateral conduction between the particles of the stratum. The stratum includes a density of foreign atom contamination of less than 1011 atoms/cm2.

Abstract: A cloud condensation nucleus spectrometer having a streamwise segmented condensation nucleus growth column. The condensation nucleus growth column includes alternating hot and cold temperature-maintaining segments arranged next to one another. The temperature difference between adjacent hot and cold temperature-maintaining segments increases from the input opening to an output opening of the condensation nucleus growth column to produce a supersaturation distribution that increases from the input to the output opening.

Abstract: A cloud condensation nucleus spectrometer having a streamwise segmented condensation nucleus growth column. The condensation nucleus growth column includes alternating hot and cold temperature-maintaining segments arranged next to one another. The temperature difference between adjacent hot and cold temperature-maintaining segments increases from the input opening to an output opening of the condensation nucleus growth column to produce a supersaturation distribution that increases from the input opening to the output opening.

Abstract: An aerosol detection system for measuring particle number distribution with respect to particle dimension in an aerosol sample. The system includes an alternating dual-bag sampler, a radially classified differential mobility analyzer, and a condensation nucleus counter. Pressure variations in sampling are compensated by feedback control of volumetric flow rates using a plurality of flow control elements.

Abstract: A scanning differential mobility analysis system having a charging device, a scanning differential mobility analyzer, a flow control, and a particle detector. The charging probability and the flow rates can be dynamically adjusted according to the instant size of the particles under measurement.

Abstract: An aerosol detection system for measuring particle number distribution with respect to particle dimension in an aerosol sample. The system includes an alternating dual-bag sampler, a radially classified differential mobility analyzer, and a condensation nucleus counter. Pressure variations in sampling are compensated by feedback control of volumetric flow rates.

Abstract: The present invention provides a differential mobility analyzer for the classification of aerosols, comprising a chamber having two generally parallel faces and means to confine gases in the chamber, one of the faces having a generally arcuate, annular sheath air channel having an axis of symmetry, other of the faces having a generally arcuate, annular aerosol channel having an axis of symmetry generally coincident with the axis of symmetry of the sheath air channel, a first one of the faces having a sample flow aperture generally aligned with the axis of symmetry of the sheath air channel, a second one of the faces having an excess flow aperture generally aligned with the axis of symmetry of the sheath air channel, and means for maintaining an electric potential difference between the faces.

Abstract: The present invention provides a differential mobility analyzer for the classification of aerosols, comprising a chamber having two generally parallel faces and means to confine gases in the chamber, one of the faces having a generally arcuate, annular sheath air channel having an axis of symmetry, other of the faces having a generally arcuate, annular aerosol channel having an axis of symmetry generally coincident with the axis of symmetry of the sheath air channel, a first one of the faces having a sample flow aperture generally aligned with the axis of symmetry of the sheath air channel, a second one of the faces having an excess flow aperture generally aligned with the axis of symmetry of the sheath air channel, and means for maintaining an electric potential difference between the faces.

Abstract: A method of producing submicron nonagglomerated particles in a single stage reactor includes introducing a reactant or mixture of reactants at one end while varying the temperature along the reactor to initiate reactions at a low rate. As homogeneously small numbers of seed particles generated in the initial section of the reactor progress through the reactor, the reaction is gradually accelerated through programmed increases in temperature along the length of the reactor to promote particle growth by chemical vapor deposition while minimizing agglomerate formation by maintaining a sufficiently low number concentration of particles in the reactor such that coagulation is inhibited within the residence time of particles in the reactor. The maximum temperature and minimum residence time is defined by a combination of temperature and residence time that is necessary to bring the reaction to completion.

Abstract: An automated rain water collector is disclosed to collect a plurality of successive rain water samples, comprised of a reservoir into which rain water is collected and discharged, and a motor-driven turntable which holds a plurality of sample bottles. When the reservoir is filled to a predetermined volume, means, such as a liquid level sensor, actuates a valve to open same and discharge the liquid sample from the reservoir into one of the bottles at a filling station on the turntable. The valve then closes and the turntable rotates to index the next bottle beneath the reservoir at the filling station, and the operation is repeated to fill the latter bottle. When all of the bottles on the turntable have been filled, the indexing means is deactivated and liquid accumulating in the reservoir is diverted to an overflow bottle.

Abstract: A cloud water collector is disclosed comprised of a sampler duct having a plurality of spaced Teflon strands, in the form of screens, mounted across the conduit at an acute angle facing the open inlet of the conduit. Droplets in a cloud sample are drawn into the conduit by a fan located at the back end of the conduit, impact upon the Teflon strands and are drawn down to the lower ends of the strands, where they drop and the accumulated droplets are diverted to a sample bottle for collection. The cloud water collector can be automated to collect a plurality of successive cloud water samples by an automated sampler containing a reservoir into which cloud water obtained in the cloud water collector is discharged. A motor-driven turntable is provided which holds a plurality of sample bottles.