Method and apparatus for characterization of aerosols

A method for the quantitative and qualitative characterization of hydrocarbon containing particles in an aerosol, comprising:

• using an aerosol, which has been brought to at least one predetermined temperature sufficient for evaporation or decomposition or preventing condensation of molecules on particles of said aerosol;
• exposing said aerosol to an electromagnetic radiation having photon energies which are below the ionization energy of the carrier gas of the aerosol and above the work function of said aerosol particles for activating said aerosol particles to cause said aerosol particles to emit electrons and attain an electric charge corresponsingly;
• and
• measuring said electric charge of said aerosol particles.

An apparatus for characterization of particles in an aerosol, said apparatus comprising:

• an essentially closed chamber comprising a gas inlet, a gas outlet, and means for establishing an aerosol flow through said chamber;
• means mounted in the interior of said essentially closed chamber in the region of said inlet for electrically neutralizing said aerosol;
• means for heating said aerosol, said heating means comprising measuring and control means for establishing a predetermined aerosol temperature;
• radiation means arranged within the interior of said essentially closed chamber and defining an irradiation zone for activating the heated aerosol flowing therethrough;
• said irradiation zone comprising a wall surface held at a defined electric potential and having a conductivity which is high enough to conduct the charge of ions produced by irradiation and movable to said wall surface to said defined electric potential;
• and
• at least one collector electrode mounted in the interior of said essentially closed chamber downstream of said irradiation zone for collecting electrically charged particles and electrically connected to a current or charge meter;
• said at least one collector electrode comprising a size selective particle filter mounted downstream of said irradiation zone and arranged in the flow of said aerosol, said size selective particle filter comprising an electric capacitor having two electrodes in spaced relationship and an electric field between said two electrodes, said aerosol flowing through the space between said two electrodes and said electric field having a magnitude which is high enough to deposit at least a part of the charged particles of said aerosol on the negative electrode of said capacitor, and control means connected to said electrodes of said capacitor in order to periodically change the field strength of said electric field between a lower value and a higher value.

An apparatus for characterization of particles in an aerosol, said apparatus comprising:

• an essentially closed chamber comprising a gas inlet, a gas outlet, and means for establishing an aerosol flow through said chamber;
• means mounted in the interior of said essentially closed chamber in the region of said inlet for electrically neutralizing said aerosol;
• means for bringing said aerosol to at least one predetermined temperature sufficient for evaporation or decomposition or preventing condensation of molecules on particles of said aerosol;
• radiation means arranged within the interior of said essentially closed chamber and defining an irradiation zone for activating the heated aerosol flowing therethrough;
• said irradiation zone comprising a wall surface held at a defined electric potential and having a conductivity which is high enough to conduct the charge of ions produced by irradiation and movable to said wall surface to said defined electric potential;
• and
• at least one collector electrode mounted in the interior of said essentially closed chamber downstream of said irradiation zone for collecting electrically charged particles and electrically connected to a current or charge meter.