Optimized instrument configurations for tandem particle mass analyzer and single particle-soot photometer experiments. (February 2022)

• Record Type: Journal Article
• Authors: Naseri, A.; Sipkens, T.A.; Rogak, S.N.; Olfert, J.S.
• Is Part Of: Journal of aerosol science. Volume 160(2022)
• Publication Date: 2022-02
• Subjects: Tandem measurements -- Centrifugal particle mass analyzer (CPMA) -- Single-particle soot photometer (SP2) -- Data inversion -- 1st order tikhonov regularization; Aerosols -- Periodicals; Aerosols -- Periodicals; Aérosols -- Périodiques; 541.34515
• DOI: 10.1016/j.jaerosci.2021.105897
• Languages: English
• ISSNs: 0021-8502

Abstract

Abstract : Tandem centrifugal particle mass analyzer (CPMA)-single-particle soot photometer (SP2) arrangements provide a measure of the non-refractory components of soot. In such a system, the CPMA is used to classify particles by mass-to-charge ratio ( i.e., total particle mass m p ), and the SP2 measures the mass of rBC ( i.e., m rBC ) within each particle. Data inversion can then be used to compute the two-dimensional total particle-non-refractory black carbon (rBC) ( m p - m rBC ) distribution, mapping out the distribution of non-refractory material on rBC particles. He present study derives the optimum sampling settings ( i.e., the number of CPMA setpoints per decade, the number of SP2 bins per decade, CPMA resolution, and the number of SP2 counts per CPMA setpoint) to accurately reconstruct m p - m rBC distributions. Monte Carlo sampling is used to realize the sensitivity of reconstruction error to experimental inputs across a range of distribution widths. General recommendations for a typical aged atmospheric aerosol include: (i) large numbers of SP2 bins per decade ( n s ' = 64), (ii) a preference for higher SP2 sampling counts per CPMA setpoint ( N s > 10 4 ), (iii) a moderate number of CPMA setpoints per decade ( n c ' = 3 to 8), (iv) CPMA resolution around 1.0, and (v) a high CPMA flow rate (1.5 L/min). These settings generally result in reconstruction accuracies below 3%. These recommendations vary based on the concentration of the aerosol, the time available for the measurement, and the width of the distribution. Optimized CPMA-SP2 settings are presented for example distributions as a function of aerosol concentration and desired measurement time.