Calibration of a photoacoustic spectrometer cell using light absorbing aerosols. A technical note.

Multi-pass photoacoustic spectrometer (PAS) is an important tool for the direct measurement of light absorption by atmospheric aerosol. And accurate PAS measurements require an accurate calibration of its signal. Ozone is often used for calibrating the PAS by relating the instrument signal to the absorption coefficient measured by an independent method such as cavity ring down spectroscopy (CRD), cavity enhanced spectroscopy (CES) or an ozone monitor. We report here a calibration method that uses measured absorption coefficients of aerosolized, light absorbing organic materials and offer an alternative approach to calibrate the PAS at 404 nm. To implement this method we first determined the complex refractive index of an organic dye using spectroscopic ellipsometry, and then we use this well characterized material as a standard material for PAS calibration. [ABSTRACT FROM AUTHOR]