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Search Publications by: James Radney (Fed)

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Displaying 1 - 18 of 18

Absorption Spectra of Martian Dust Simulants

February 18, 2022
James Radney, Christopher D. Zangmeister
Understanding the climate of Mars requires a detailed understanding of the optical properties of Martian dust as it is a ubiquitous component of the atmosphere. The need for a consensus motivates measurements of terrestrial simulants under controlled

Hydration of Hydrophilic Cloth Facial Coverings Greatly Increases the Filtration Properties for Nanometer and Micrometer-sized Particles

March 8, 2021
Christopher D. Zangmeister, James Radney, Matthew E. Staymates, Edward P. Vicenzi, Jamie Weaver
Filtration efficiencies (FE) of natural, synthetic, and blended fabrics were measured as a function of relative humidity (RH) for particles with mobility diameters between 50 nm and 825 nm. Fabrics were equilibrated at 99 % RH, mimicking conditions

Comparison of three essential submicron aerosol measurements: mass, size and shape

May 28, 2020
Qi Yao, Akua Asa-Awuku, Christopher D. Zangmeister, James Radney
An instrumental trifecta now exists for aerosol separation and classification by mobility diameter (Dm), aerodynamic diameter (Dae) and mass (mp) utilizing a differential mobility analyzer (DMA), aerodynamic aerosol classifier (AAC) or aerosol particle

Measured In-situ Mass Absorption Spectra for Nine Forms of Highly-absorbing Carbonaceous Aerosol

April 23, 2018
Christopher D. Zangmeister, Rian You, Elizabeth M. Lunny, Arne Jacobson, Mitchio Okumura, Michael R. Zachariah, James G. Radney
Mass absorption coefficient spectra were measured between λ = 500 nm and 840 nm for nine forms of highly-absorbing carbonaceous aerosol: five samples generated from gas-, liquid- and solid- fueled flames; spark-discharge fullerene soot; graphene and

Light Source Effects on Aerosol Photoacoustic Spectroscopy Measurements

October 6, 2016
James G. Radney, Christopher D. Zangmeister
Photoacoustic spectroscopy measurements of flame-generated soot aerosol coated with small amounts of water yielded absorption enhancements that were dependent on the laser used: quasi- continuous wave (Q-CW, ≈ 650 ps pulse duration and 78 MHz repetition

Packing density of rigid aggregates is independent of scale

May 14, 2014
Christopher D. Zangmeister, James G. Radney, Michael R. Zachariah
Large planetary seedlings, comets, microscale pharmaceuticals, and nanoscale soot particles are made from rigid, aggregated subunits that are compacted under low compression into larger structures spanning over 10 orders of magnitude in dimensional space

Dependence of Soot Optical Properties on Particle Morphology: Measurements and Model Comparisons

February 18, 2014
James Radney, Rian You, Xiaofei Ma, Joseph Conny, Michael R. Zachariah, Joseph T. Hodges, Christopher D. Zangmeister
We measure the mass-specific absorption and extinction cross sections for laboratory-generated soot aerosols. Two soot morphologies are investigated, both comprising fractal aggregates of nearly spherical monomers. The first type consists of monomer chains

Direct measurements of mass-specific optical cross sections of single component aerosol mixtures

July 22, 2013
James Radney, Xiaofei Ma, Keith A. Gillis, Michael R. Zachariah, Joseph T. Hodges, Christopher D. Zangmeister
The optical properties of atmospheric aerosols vary widely, being dependent upon particle composition, morphology and mixing state. This diversity and complexity of aerosols motivates measurement techniques that can discriminate and quantify a variety of