The optical and chemical properties of discharge generated organic haze using in-situ real-time techniques

Optical and physicochemical properties of secondary organic aerosol and aerosol generated from humic substances

“…Truncating the Mie fits at successively larger minimum particle diameters did not significantly change the best-fit values of the optical constants, indicating that extinction due to MCPs was negligible over the chosen size range. the literature values, and with the light scattering measurement results for AS in this work, 3,68,80,126,148 The comparisons, summarized in Table 2.1, confirm the accuracy of the calibration procedure and the experimental approach used for determining aerosol optical constants for both absorbing and scattering samples. We also note that our experimental error is comparable to the reported errors from other studies employing related techniques.…”

“…103 The early work along these lines was hampered by experimental uncertainties in the particle size distribution and number concentration, which are required for quantitative comparisons between experiment and theory. 99,119 The first two careful studies to compare experimental CW-CRDS aerosol extinction data with corresponding Mie theory model calculations were Since that time, many groups have devoted extensive effort to aerosol extinction studies using CRDS methods, for a variety of aerosol systems: laboratory scale measurements of standard materials, 70,80,98,[103][104] lab synthesized SOA, 105,[122][123] field collected atmospheric aerosol samples, 70 aerosol generated from humic substances, 80 studies of relative humidity effects (RH) on optical properties, 124 coated aerosol particles, 125 organic atmospheric haze, 126 and single particle analysis. [127][128][129][130] Other groups have focused on improving the accuracy and sensitivity of the CRDS methods by investigating errors associated with statistical fluctuations due to low particle number concentrations, 101,103,[131][132][133] and uncertainties resulting from instrumental calibration effects.…”

Glyoxal's impact on dry ammonium salts: fast and reversible surface aerosol browning

“…Glyoxal inlet concentrations, flow mixing ratios, and wall loss rates were then used to estimate glyoxal chamber concentrations. Aerosol particles were sampled via diffusion driers by Q-AMS (Aerodyne), 75 CAPS-ssa (Aerodyne, 450 nm), SMPS (TSI), CRD (530 nm) (Ugelow et al, 2017), and photoacoustic spectrometers (PAS, 405 and 530 nm) (Ugelow et al, 2017). RH sensors monitored humidity levels at the aerosol inlet, chamber outlet, and dried chamber outlet flows.…”

A novel approach to calibrating a photoacoustic absorption spectrometer using polydisperse absorbing aerosol

“…In addition to the issues of generating a monodisperse distribution, this approach to particle-based calibration requires exact knowledge of the real and imaginary refractive index of the calibration particles. The refractive index of nigrosin dye has been tested by several groups as an aerosol calibration standard, and three different groups have published estimates of the complex refractive index (RI) of nigrosin at 405 nm (Bluvshtein et al, 2017;Ugelow et al, 2017;Washenfelder et al, 2013). The three studies differ in the retrieved imaginary RI at a given wavelength by 15 %, indicating that nigrosin does not have consistent optical properties between different batches and is probably not an ideal candidate for an absorption calibration standard.…”