Angular scattering of light by a homogeneous spherical particle in a zeroth-order Bessel beam and its relationship to plane wave scattering

Preston, Thomas C.; Reid, Jonathan P.

doi:10.1364/josaa.32.001053

Cited by 21 publications

(14 citation statements)

References 38 publications

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“…The variation in particle radius and n λ is determined by fitting the complete measured PF data set to Mie theory in a self-consistent step. We previously reported the algorithms used to perform this fitting (Cotterell et al, 2015a, b;Preston and Reid, 2015). For all hygroscopic response measurements reported in this work, the RI varies with the particle size.…”

Section: Size and Ri Retrieval Using Phase Function Imagesmentioning

confidence: 99%

A complete parameterisation of the relative humidity and wavelength dependence of the refractive index of hygroscopic inorganic aerosol particles

et al. 2017

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Abstract. Calculations of aerosol radiative forcing require knowledge of wavelength-dependent aerosol optical properties, such as single-scattering albedo. These aerosol optical properties can be calculated using Mie theory from knowledge of the key microphysical properties of particle size and refractive index, assuming that atmospheric particles are well-approximated to be spherical and homogeneous. We provide refractive index determinations for aqueous aerosol particles containing the key atmospherically relevant inorganic solutes of NaCl, NaNO 3 , (NH 4 ) 2 SO 4 , NH 4 HSO 4 and Na 2 SO 4 , reporting the refractive index variation with both wavelength (400-650 nm) and relative humidity (from 100 % to the efflorescence value of the salt). The accurate and precise retrieval of refractive index is performed using singleparticle cavity ring-down spectroscopy. This approach involves probing a single aerosol particle confined in a Bessel laser beam optical trap through a combination of extinction measurements using cavity ring-down spectroscopy and elastic light-scattering measurements. Further, we assess the accuracy of these refractive index measurements, comparing our data with previously reported data sets from different measurement techniques but at a single wavelength. Finally, we provide a Cauchy dispersion model that parameterises refractive index measurements in terms of both wavelength and relative humidity. Our parameterisations should provide useful information to researchers requiring an accurate and comprehensive treatment of the wavelength and relative humidity dependence of refractive index for the inorganic component of atmospheric aerosol.

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Section: Size and Ri Retrieval Using Phase Function Imagesmentioning

confidence: 99%

A complete parameterisation of the relative humidity and wavelength dependence of the refractive index of hygroscopic inorganic aerosol particles

et al. 2017

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“…Eqs. (46), (49), (59) and (69) are used to plot I x ∞,sc (θ , π /2) and I res,x ∞,sc (θ , π /2) in the bandwidth 5°≤ θ ≤ 15°.…”

Section: Far-field Directivity Patterns For the Normalized Scattered mentioning

confidence: 99%

“…When evaluating the resonance (normalized) intensity [using the coefficients given by Eq. (69)], this enhancement is removed. Since Eq.…”

Section: Far-field Directivity Patterns For the Normalized Scattered mentioning

confidence: 99%

Resonance scattering of a dielectric sphere illuminated by electromagnetic Bessel non-diffracting (vortex) beams with arbitrary incidence and selective polarizations

Mitri

Guo

et al. 2015

Annals of Physics

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“…A laser line filter removed light at 532 nm to ensure only 473 nm light was collected. Fitting the PFs to Mie theory allowed determination of the particle radius and RI at λ D 473 nm, using the fitting algorithms and procedures described in Cotterell et al (2015a,b) and Preston and Reid (2015).…”

Section: Experimental and Numerical Methodsmentioning

confidence: 99%

“…In data sets simulating measurements on evaporating single component aerosol, the RI was constant (m D n 0 ). In data sets simulating the hygroscopic response of inorganic aerosol, n varied with particle size and was described using Equation (2), where n 532,1 and n 532,2 dictate the variation in n with radius (Cotterell et al 2015a,b;Preston and Reid 2015).…”

Section: ¡3mentioning

confidence: 99%

Assessing the accuracy of complex refractive index retrievals from single aerosol particle cavity ring-down spectroscopy

Cotterell

Preston

Orr-Ewing

et al. 2016

Aerosol Science and Technology

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Cavity ring-down spectroscopy (CRDS) of single, optically manipulated aerosol particles affords quantitative retrieval of refractive indices for particles of fixed or evolving composition with high precision. Here, we quantify the accuracy with which refractive index determinations can be made by CRDS for single particles confined within the core of a Bessel laser beam and how that accuracy is degraded as the particle size is progressively reduced from the coarse mode (>1 mm radius) to the accumulation mode (<500 nm radius) regime. We apply generalized Lorenz-Mie theory to the intra-cavity standing wave to explore the effect of particle absorption on the distribution of extinction cross section determinations resulting from stochastic particle motion in the Bessel beam trap. The analysis provides an assessment of the accuracy with which the real, n, and imaginary, k, components of the refractive index can be determined for a single aerosol particle. EDITOR Spyros Pandis

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Angular scattering of light by a homogeneous spherical particle in a zeroth-order Bessel beam and its relationship to plane wave scattering

Cited by 21 publications

References 38 publications

A complete parameterisation of the relative humidity and wavelength dependence of the refractive index of hygroscopic inorganic aerosol particles

A complete parameterisation of the relative humidity and wavelength dependence of the refractive index of hygroscopic inorganic aerosol particles

Resonance scattering of a dielectric sphere illuminated by electromagnetic Bessel non-diffracting (vortex) beams with arbitrary incidence and selective polarizations

Assessing the accuracy of complex refractive index retrievals from single aerosol particle cavity ring-down spectroscopy

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