SINGLE-PARTICLE CHARACTERIZATION BY TIME-OF-FLIGHT MASS-SPECTROMETRY

We have built a particle analyzer capable of real-time detection and characterization of individual particles. Particle analysis is accomplished by pulsed laser ablation of a particle followed by time-of-flight mass spectrometry of the resulting atomic and molecular ions. The detected ions are characteristic of a particle's molecular composition. Particles of different sizes (0.02-10 mu m) and compositions (ammonium sulfate, silica, rubidium nitrate, and cesium nitrate) have been detected and characterized. Even refractory materials, e.g. silica, are easily detected.