MASS MONITORING OF CARBONACEOUS AEROSOLS WITH A SPECTROPHONE

The feasibility of using light absorption as an in situ mass monitor for carbonaceous aerosols has been studied. The absorption measurements were made using a helium-cadmium laser with a measured output of 3 mW at 4166 A chopped at 4000 Hz to power an acoustically resonant spectrophone. Coupling of the spectrophone with a laboratory flow tube system for generating carbonaceous aerosols has produced the following results: (1) spectrophone output is proportional to carbonaceous aerosol mass concentration as independently determined by filter collection and weighing; (2) the absorption coefficient of carbonaceous aerosols is 17 m2 g-1 at 4166 Å in rough agreement with previously measured values for bulk carbon and graphite samples of 1.4-15.0 m2 g-1. The spectrophone provides a means of continuous monitoring of carbonaceous aerosols and is for less time-consuming than filter collection techniques. Potential applications include real time monitoring of vehicle exhaust, laboratory combustion research studies and field measurements. © 1979.