A gaseous sample and a reference volume are traversed by electromagnetic radiation and the absorption caused by the sample, as given by the difference between the radiation intensities after passage through the sample and the reference volume, is measured and used as a measurement value.PPBy means of radiation of a wavelength in the range between 3.8 and 4.15 m, the specific mass of particles characterized by broadband absorption--especially graphitic particles--is determined; by means of radiation of a frequency band centered in the wavelength range of 3.35 to 3.5 m, whose 3 dB bandwidth does not exceed 0.3 m, the specific total mass of aerosol particles is determined, and by the additional measurement of the resonance absorption at a wavelength in the range of 3.35 to 3.5 m the percentages of both graphitic and organically soluble particles are determined separately. PPIn a device for the implementation of the method a beam splitter transmits the radiation of a common radiation source to the sample and the reference volume; by means of a deflection unit the partial beams are reunited and transmitted to an evaluation unit in front of a common detector. With the aid of two transparent plates with parallel faces which are inclined against the incident beam at the Brewster angle, and are inserted in the beam splitter and in the deflection unit, the partial beams are polarized differently; as selector unit a rotatable polarization analyzer is used.
展开▼
