Novel design of a resonant photoacoustic spectrophone for elemental carbon mass monitoring

An improved design of a resonant photoacoustic spectrophone is reported for aerosol absorption measurements by using a near‐infrared laser diode (λ=802 nm; P=450 mW) in combination with a double‐pass configuration for excitation of azimuthal modes and right‐angle mounting of two electret microphones for signal detection. As a result of the new spectrophone setup a small‐sized portable sensor system for real‐time in situ elemental carbon monitoring is presented. The detection limit is estimated to 4.5×10−8 cm−1 or 1.5 μg elemental carbon per m 3.