Extinction efficiencies of coated absorbing aerosols measured by cavity ring down aerosol spectrometry

Riziq, A. Abo; Trainic, Miri; Erlick, Carynelisa; Segre, Enrico; Rudich, Yinon

doi:10.5194/acp-8-1823-2008

Cited by 66 publications

(63 citation statements)

References 54 publications

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“…This method is only appropriate for a monodisperse size distribution, and required that we correct the measured optical extinction for multiple-charged particles. The assumed refractive index used for the subtraction of extinction due to multiple-charged particles was 1.52 + 0i (Abo Riziq et al, 2008), with no wavelength dependence. The refractive index was independently determined for 13 aerosol diameters from 200-800 nm, with an average value of 1.51 (±0.01) + 0.02 (±0.01)i.…”

Section: Determination Of Complex Refractive Index For Ammonium Sulfamentioning

confidence: 99%

“…For example, commercial aethalometer instruments have provided filter-based measurements over a wide spectral range of discrete wavelengths (e.g., Rizzo et al, 2011), but may be subject to artifacts, for example due to particles on the filter . Recent advances in photo-acoustic spectroscopy (PAS) (Arnott et al, 1999;Lack et al, 2006Lack et al, , 2012 and cavity ring-down spectroscopy (CRDS) (Strawa et al, 2003;Baynard et al, 2007;Abo Riziq et al, 2008;Langridge et al, 2011) allow rapid, accurate, in situ measurements of optical absorption and extinction, but have so far been limited to single, discrete wavelengths. Similarly, cavity attenuated phase shift spectroscopy (CAPS) instruments may employ broadband LED light sources, but do not resolve the extinction as a function of wavelength (Kebabian et al, 2007;Massoli et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Broadband measurements of aerosol extinction in the ultraviolet spectral region

et al. 2013

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Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360–390 and 385–420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye). We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross sections over the 360–420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with the literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (± 0.03) + 0.19 (± 0.08)i at 360 nm and 1.63 (± 0.03) + 0.21 (± 0.05)i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (± 0.02) + 0.07 (± 0.06)i at 360 nm and 1.66 (± 0.02) + 0.06 (± 0.04)i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross section, and complex refractive index as a function of wavelength

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Section: Determination Of Complex Refractive Index For Ammonium Sulfamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Broadband measurements of aerosol extinction in the ultraviolet spectral region

et al. 2013

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“…The index of refraction is varied as described in Eqs. (8) and (10). The contrast term used in the calculations is n 1 − n 0 = 0.07.…”

Section: B Concentric Fluctuationsmentioning

confidence: 99%

“…scattering and absorption cross sections [10]. A candidate for detecting small changes in the relative positions of a core-shell system is ellipsometric light scattering (ELS), as it has been demonstrated to be very sensitive to changes in shell thickness and index of refraction [11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Mie scattering by soft core-shell particles and its applications to ellipsometric light scattering

Ross

Sigel

2012

Phys. Rev. E

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Through the use of Mie theory generalized to multiple spheres, the derivatives of the scattering matrix elements and ellipsometric scattering variables are found as a function of shell thickness and nonconcentricity for core-shell particles. In particular, for the case of a core-shell sphere system where the centers are not concentric, the derivatives are taken with respect to the line segment describing the distance between spherical centers. The derivatives of the scattering matrix elements can be used to calculate the changes in ellipsometric light scattering, allowing for sensitivity and precision in quantitative models of fluctuations in core-shell systems. Computed results giving model contrast for a variety of sizes and fluctuation modes are used to design and guide novel light-scattering experiments currently underway.

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“…To date, CRDS has been used in both field [30,[34][35][36][37][38] and laboratory studies [13,31,[39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57], using both pulsed [13,30,36,37,[39][40][41][42]53,[58][59][60] and cw-laser [31,43,44,46,52] systems. Aerosol extinction at wavelengths ranging from the near UV [12,30] to the infrared [31,43,44,47] has been studied, with most measurements performed in the visible region.…”

Section: Cavity Ring Down Measurements Of Light Extinction By Aerosolmentioning

confidence: 99%

Novel optical techniques for measurements of light extinction, scattering and absorption by single aerosol particles

Miles¹,

Carruthers²,

Reid³

2011

Laser & Photonics Reviews

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Aerosol particles play important roles in a broad range of scientific disciplines, from atmospheric chemistry and physics, to the delivery of fuels for combustion and drugs to the lungs, and extending to industrial processes such as spray drying. Measurements of the light extinction, scattering and absorption by ensembles of aerosol particles can be used to non-intrusively characterise aerosol particle samples. However, such measurements often lead to ambiguity in interpreting the properties and processes occurring on individual particles. In this review, recent developments in the use of laser based techniques to isolate and manipulate single particles and to characterise them will be highlighted. In particular, the use of cavity ring down spectroscopy, Bessel beams and optical tweezers for investigating light extinction, scattering and absorption, respectively, will be considered. The prospects for using optical techniques to interrogate the fundamental processes occurring in aerosol at the single particle level are discussed.

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Extinction efficiencies of coated absorbing aerosols measured by cavity ring down aerosol spectrometry

Cited by 66 publications

References 54 publications

Broadband measurements of aerosol extinction in the ultraviolet spectral region

Broadband measurements of aerosol extinction in the ultraviolet spectral region

Mie scattering by soft core-shell particles and its applications to ellipsometric light scattering

Novel optical techniques for measurements of light extinction, scattering and absorption by single aerosol particles

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