An instrument has been developed to analyze the size and chemical comp
osition of individual, air-borne particles. The particles are introduc
ed into the vacuum chamber of a time-of-flight mass spectrometer where
they are detected and sized using an aerodynamic principle. After siz
ing, the particles are vaporized by an excimer laser and the resulting
ions are analyzed. Experiments have shown that polystyrene particles
1 mu m in diameter are not fully vaporized by the laser pulse. The ins
trument has been characterized and some examples of measurements on am
bient and artificial aerosols are presented. Coyright (C) 1996 Elsevie
r Science Ltd