Complex refractive indices in the TeraHertz domain of samples from atmospheric aerosol sources

Detailed knowledge of the complex refractive indices (m) of fine- and coarse-mode aerosols is important for enhancing understanding of the effect of atmospheric aerosol on climate. However, studies on obtaining aerosol modal m values are particularly scarce. This study proposes a method for inferring m values of fine- and coarse-mode aerosol using the inversion products from the AERONET ground-based aerosol robotic network. By identifying the aerosol type, modal m values are constrained and then inferred based on a maximum likelihood method. Numerical tests showed that compared with the reference values, our method slightly overestimates the real parts of the refractive indices (n), but underestimates the imaginary parts (k) by 2.11% ± 11.59% and 8.4% ± 26.42% for fine and coarse modes, respectively. We applied this method to 21 AERONET sites around China, which yielded annual mean m values of (1.45 ± 0.04) + (0.0109 ± 0.0046)i and (1.53 ± 0.01) + (0.0039 ± 0.0011)i for fine- and coarse-mode aerosols, respectively. It is observed that the fine mode n decreased from 1.53 to 1.39 with increasing latitude, while fine mode k values were generally larger than 0.008 over most of China. The coarse-mode n and k ranged from 1.52 to 1.56 and from 0.002 to 0.006, respectively.

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Tracing of atmospheric aerosol sources using stable carbon isotopes

Lithuanian Journal of Physics ◽

10.3952/lithjphys.48309 ◽

2008 ◽

Vol 48 (3) ◽

pp. 259-264 ◽

Cited By ~ 23

Author(s):

A. Garbaras

Keyword(s):

Carbon Isotopes ◽

Atmospheric Aerosol ◽

Stable Carbon Isotopes ◽

Stable Carbon ◽

Aerosol Sources

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Nuclear Magnetic Resonance Characterization of Water Soluble Organic Carbon of Atmospheric Aerosol Types

Natural Product Communications ◽

10.1177/1934578x19849972 ◽

2019 ◽

Vol 14 (5) ◽

pp. 1934578X1984997 ◽

Cited By ~ 3

Author(s):

Marie-Cecile G. Chalbot ◽

Ilias G. Kavouras

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Organic Carbon ◽

Atmospheric Aerosol ◽

Road Dust ◽

Water Soluble ◽

Natural Soil ◽

Water Soluble Organic Carbon ◽

Soluble Organic Carbon ◽

Aerosol Sources

The water soluble organic carbon of the prevalent atmospheric aerosol sources (traffic exhausts, paved road dust, agricultural soil, native soil, wood combustion, epicuticular waxes from pine and broad-leaved trees, and pollen) has been characterized using 1H (1-dimensional), 1H-1H-correlation spectroscopy and 1H-13C-heteronuclear single quantum correlation 2-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy. Traffic exhaust particles were mainly constituted of primary alcohols, carbohydrates, functionalized olefins, C3 and C4 oxy- and hydroxyl-carboxylic acids, and short-chain alkanes. Road dust was a mixture of soil particles and traffic components. Agricultural, natural, road dust, and traffic particles contained broad signals that were attributed to poly-carboxylic compounds typically found in humic compounds and humic-like substances. Traces of traffic particles (ie, peaks in the 7.3-7.5 ppm [phthalic acid derivatives] and signals found in the 0.5-3 ppm originating from functionalized carboxylic acids) were also found in natural soil dust. Long-chain (>C3) fatty acids and amino acids were found in road dust, natural soil, pine trees waxes, pollen, and woodburning. The aromatic region mainly constituted of lignin derivatives and cellulose/hemicellulose pyrolysis products (signals in 2D-NMR) in woodburning. Primary biogenic and woodburning particles were uniquely clustered as compared to traffic exhausts, road, agricultural, and natural dust based on the relative ratio of hydro-oxygenated functional groups (H-C-O and H-C-C=O) to the sum of aliphatics. Overall, source-specific NMR spectrometric fingerprints, functional composition profiles, and several organic compounds were identified allowing for the reconciliation of ambient organic aerosol sources including the degree of atmospheric aging.

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Contribution of Aerosol Sources to Health Impacts

Atmosphere ◽

10.3390/atmos12060730 ◽

2021 ◽

Vol 12 (6) ◽

pp. 730

Author(s):

Daniele Contini ◽

Ying-Hsuan Lin ◽

Otto Hänninen ◽

Mar Viana

Keyword(s):

Risk Factors ◽

Human Health ◽

Environmental Risk ◽

Atmospheric Aerosol ◽

Environmental Risk Factors ◽

Health Impacts ◽

Premature Deaths ◽

Aerosol Sources

Atmospheric aerosol is one of the major leading environmental risk factors for human health worldwide, potentially causing several million premature deaths per year [1,2]. [...]

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Modification, Calibration, and Performance of the Ultra-High Sensitivity Aerosol Spectrometer for Particle Size Distribution and Volatility Measurements During the Atmospheric Tomography (ATom) Airborne Campaign

10.5194/amt-2017-293 ◽

2017 ◽

Cited By ~ 1

Author(s):

Agnieszka Kupc ◽

Christina Williamson ◽

Nicholas L. Wagner ◽

Mathews Richardson ◽

Charles A. Brock

Keyword(s):

Refractive Index ◽

Ammonium Sulfate ◽

Atmospheric Aerosol ◽

High Sensitivity ◽

Chemical Processes ◽

Refractive Indices ◽

Ambient Particles ◽

And Performance ◽

Counting Statistics ◽

Area And Volume

Abstract. Atmospheric aerosol is a key component of the chemistry and climate of the Earth's atmosphere. Accurate measurement of the concentration of atmospheric particles as a function of their size is fundamental to investigations of particle microphysics, optical characteristics, and chemical processes. We describe the modification, calibration, and performance of two commercially available, ultra-high sensitivity aerosol spectrometers (UHSASs) as used on the NASA DC-8 aircraft during the Atmospheric Tomography Mission (ATom). To avoid sample flow issues related to pressure variations during aircraft altitude changes, we installed a laminar flow meter on each instrument to measure sample flow directly at the inlet as well as flow controllers to maintain constant volumetric sheath flows. In addition, we added a compact thermodenuder operating at 300 °C to the inlet line of one of the instruments. With these modifications, the instruments are capable of making accurate (ranging from 7 % for Dp 0.13 μm), precise ( 1000 to 225 hPa, while simultaneously providing information on particle volatility. We assessed the effect of uncertainty in the refractive index (n) of ambient particles that are sized by the UHSAS assuming the refractive index of ammonium sulfate (n = 1.52). For calibration particles with n between 1.44 and 1.58, the UHSAS diameter varies by +4/−10 % relative to ammonium sulfate. This diameter uncertainty associated with the range of refractive indices (i.e. particle composition) translates to aerosol surface area and volume uncertainties of +8.4/−17.8 % and +12.4/−27.5 % respectively. Additional to sizing uncertainty, low counting statistics can lead to uncertainties of

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The spindle stage: A powerful optical tool

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100102341 ◽

1988 ◽

Vol 46 ◽

pp. 52-53

Author(s):

Mickey E. Gunter ◽

F. Donald Bloss

Keyword(s):

Significant Error ◽

Optical Data ◽

Refractive Indices ◽

Axis Of Rotation ◽

Polarizing Microscope ◽

Microscope Stage

A single, reasonably homogeneous, nonopaque 30-to-300 μm crystal, mounted on a spindle stage and studied by immersion methods under a polarizing microscope, yields optical data frequently sufficient to identify and characterize a substance unequivocally. The data obtainable include (1) the orientation of the crystal's principal vibration axes and (2) its principal refractive indices, to within 0.0002 if desired, for light vibrating along these principal vibration axes. Spindle stages tend to be simple and relatively inexpensive, some costing less than $50. They permit rotation of the crystal about a single axis which is parallel to the microscope stage. This spindle or S-axis is thus perpendicular to the M-axis, namely the microscope stage's axis of rotation.A spindle stage excels when studying anisotropic crystals. It orients uniaxial crystals within minutes and biaxial crystals almost as quickly so that their principal refractive indices - ɛ and ω (uniaxial); α, β and γ (biaxial) - can be determined without significant error from crystal misorientation.

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Light microscopy of ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015037x ◽

1993 ◽

Vol 51 ◽

pp. 908-909

Author(s):

Walter C. McCrone

Keyword(s):

Refractive Index ◽

Light Microscopy ◽

Light Microscope ◽

Polarized Light ◽

Refractive Indices ◽

Complete Coverage ◽

The Subject ◽

Lower Refractive Index

An excellent chapter on this subject by V.D. Fréchette appeared in a book edited by L.L. Hench and R.W. Gould in 1971 (1). That chapter with the references cited there provides a very complete coverage of the subject. I will add a more complete coverage of an important polarized light microscope (PLM) technique developed more recently (2). Dispersion staining is based on refractive index and its variation with wavelength (dispersion of index). A particle of, say almandite, a garnet, has refractive indices of nF = 1.789 nm, nD = 1.780 nm and nC = 1.775 nm. A Cargille refractive index liquid having nD = 1.780 nm will have nF = 1.810 and nC = 1.768 nm. Almandite grains will disappear in that liquid when observed with a beam of 589 nm light (D-line), but it will have a lower refractive index than that liquid with 486 nm light (F-line), and a higher index than that liquid with 656 nm light (C-line).

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