Aerosol optical absorption and spectral dependence measurement with photoacoustic spectroscopy

2020 ◽  
Author(s):  
Yuan Cao ◽  
Kun Liu ◽  
Weidong Chen ◽  
Xiaoming Gao
Keyword(s):  
Optical Absorption ◽  
Biomass Burning ◽  
Light Absorption ◽  
Optical Absorption Coefficient ◽  
Time Range ◽  
Photoacoustic Spectrometer ◽  
Multi Wavelength ◽  
Winter Time ◽  
Absorption Characteristics

<p>Light-absorbing carbonaceous aerosols mainly generated from the combustion of biomass and fossil fuels, play an important role in the global environment <sup>[1]</sup>. Multi-wavelength in-situ measurement of carbonaceous aerosol optical absorption is important both for reduce errors in assessing radiative forcing and component identification or source appointment of aerosols (such as biomass burning and diesel soot) with absorption Ångström exponent (AAE) <sup>[2]</sup>. A differential photoacoustic spectrometer (PAS) using a 438 nm laser diode was developed for simultaneously measure the aerosol optical absorption coefficient and the concentration of NO<sub>2</sub>. In order to evaluate the reliability of the differential photoacoustic spectrometer, we compared the NO<sub>2 </sub>concentration measured by PAS with the data from environmental monitoring station and showed good consistency. In the actual atmospheric measurement process, we observed a good correlation between the light absorption characteristics of aerosols and the concentration of NO<sub>2</sub> within a certain time range. In addition, a novel multi-wavelength photoacoustic spectrometer (MW-PAS) was developed to measure the aerosol optical absorption coefficients and its wavelength-dependent characteristics in the UV-VIS-NIR bands (405, 638, 808 nm). The performance of MW-PAS was evaluated by measuring the light absorption characteristics of kerosene soot aerosol. The measurement results are agreed with the results reported in literatures <sup>[3]</sup>.</p><p> </p><p>Reference</p><p>[1] J.G. Radney, R. You, M.R. Zachariah, C.D. Zangmeister, Direct in-situ mass specific absorption spectra of biomass burning particles generated from smoldering hard and softwoods. Environ. Sci. Technol. <strong>51</strong>, 5622-5629 (2017)</p><p>[2] T. Ajtai, N. Utry, M. Pintér, B. Major, G. Szabó, A method for segregating the optical absorption properties and the mass concentration of winter time urban aerosol. Atmos. Environ.<strong>122</strong>, 313-320 (2015)</p><p>[3] M. Gyawali, W.P. Arnott, R.A. Zaveri, C. Song, H. Moosmüller, L. Liu, M.I. Mishchenko, L.-W.A. Chen, M.C. Green, J.G. Watson, and J.C. Chow, Photoacoustic optical properties at UV, VIS, and near IR wavelengths for laboratory generated and winter time ambient urban aerosols. Atmos. Chem. Phys. <strong>12</strong>, 2587-2601 (2012)</p>

scholarly journals Investigation of Light Absorption in a ZnS Quantum Dot

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Hojjatollah K. Salehani ◽  
Maedeh Zakeri
Keyword(s):  
Magnetic Field ◽  
Optical Absorption ◽  
Quantum Dot ◽  
Excited States ◽  
Light Absorption ◽  
Blue Shift ◽  
Optical Absorption Coefficient ◽  
Parabolic Confinement ◽  
Parabolic Confinement Potential ◽  
The Magnetic Field

The light absorption of a ZnS quantum dot with a parabolic confinement potential is studied in this paper in the presence of magnetic field perpendicular to dot plane. The Schrodinger equation of a single electron is solved numerically, and energy spectra and wave functions are obtained. Then, the optical absorption coefficients in transition from ground state to different excited states are calculated. The effects the magnetic field and quantum dot width on the optical absorption are investigated. It is found that the optical absorption coefficient has a blue shift by increasing of magnetic field or confinement strength of quantum dot.

scholarly journals Light absorption of brown carbon in eastern China based on 3-year multi-wavelength aerosol optical property observations at the SORPES station and an improved Absorption Ångstrom exponent segregation method

2018 ◽  
Author(s):  
Jiaping Wang ◽  
Wei Nie ◽  
Yafang Cheng ◽  
Yicheng Shen ◽  
Xuguang Chi ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Light Absorption ◽  
Mie Theory ◽  
Brown Carbon ◽  
Angstrom Exponent ◽  
Lagrangian Modeling ◽  
Ångström Exponent ◽  
Multi Wavelength ◽  
Ångstrom Exponent

Abstract. Brown carbon (BrC), a certain group of organic carbon (OC) with strong absorption from the visible to ultraviolet (UV) wavelengths, makes considerable contribution to light absorption on both global and regional scales. High concentration and proportion of OC has been reported in China, but studies of BrC absorption based on long-term observations are rather limited in this region. In this study, we reported 3-year results of light absorption of BrC based on continuous measurement at the Station for Observation Regional Processes of the Earth System (SORPES) in the Yangtze River Delta, China combined with Mie-theory calculation. Light absorption of BrC was obtained using an improved Absorption Ångstrom exponent (AAE) segregation method to calculate AAE of pure and non-absorbing coated black carbon (BC) at each time step based on Mie-theory simulation and measurement of multi-wavelength aerosol light absorption. By using this improved method, the variation of AAE over time is taken into consideration, making it applicable for long-term analysis. The yearly average light absorption of BrC (babs_BrC) at 370 nm was 4.3 Mm−1 at the SORPES station. The contribution of BrC to total aerosol absorption (PBrC) at 370 nm ranged from 6 % to 18 % (10th and 90th percentiles, respectively), and reached up to ~ 28 % in biomass burning-dominant season and winter. Both babs_BrC and PBrC exhibited clear seasonal cycles with two peaks in later spring/early summer (May–June, babs_BrC ~ 4 Mm−1, PBrC ~ 11 %) and winter (December, babs_BrC ~ 12 Mm−1, PBrC ~ 17 %), respectively. Lagrangian modeling and chemical signature observed at the site suggested that open biomass burning and residential emissions were the dominate sources influencing BrC in the two seasons.

scholarly journals Absorbing aerosol in the troposphere of the Western Arctic during the 2008 ARCTAS/ARCPAC airborne field campaigns

2011 ◽  
Vol 11 (1) ◽  
pp. 1543-1594 ◽  
Author(s):  
C. S. Mc Naughton ◽  
A. D. Clarke ◽  
S. Freitag ◽  
V. N. Kapustin ◽  
Y. Kondo ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Aerosol Size Distribution ◽  
Brown Carbon ◽  
Middle Troposphere ◽  
Mass Absorption ◽  
Western Arctic ◽  
Field Campaigns

Abstract. In the spring of 2008 NASA and NOAA funded the ARCTAS and ARCPAC field campaigns as contributions to POLARCAT, a core IPY activity. During the campaigns the NASA DC-8, P-3B and NOAA WP-3D aircraft conducted over 150 h of in-situ sampling between 0.1 and 12 km throughout the Western Arctic north of 55° N (i.e. Alaska to Greenland). All aircraft were equipped with multiple wavelength measurements of aerosol optics, trace gas and aerosol chemistry measurements, as well as direct measurements of black carbon mass and the aerosol size distribution. Late April of 2008 proved to be exceptional in terms of Asian biomass burning emissions transported to the Western Arctic. Though these smoke plumes account for only 11–14% of the samples within the Western Arctic domain, they account for 43–47% of the total burden of black carbon. Light absorbing carbon from urban/industrial activities and biomass burning together account for 93–98% of total light absorption in the middle troposphere. Light absorption by mineral dust accounts for the remaining absorption in the middle troposphere, but up to 14% near the surface and in the upper troposphere below the tropopause. Stratifying the data to reduce the influence of dust allows us to determine mass absorption efficiencies for black carbon of 11.2±0.8, 9.5±0.6 and 7.4±0.7 m2 g−1 at 470, 530 and 660 nm wavelengths. These estimates are consistent with 35–80% enhancements in 530 nm absorption due to clear or slightly absorbing coatings of pure black carbon particulate. Assuming a 1/λ wavelength dependence for BC absorption, and assuming that refractory aerosol (420 °C, τ = 0.1 s) in low-dust samples is dominated by brown carbon, we derive mass absorption efficiencies for brown carbon of 0.83±0.15 and 0.27±0.08 m2 g−1 at 470 and 530 nm wavelengths. Estimates for the mass absorption efficiencies of Asian Dust are 0.034 m2 g−1 and 0.017 m2 g−1. However the values are highly uncertain due to the limitations imposed by PSAP instrument noise. In-situ ARCTAS/ARCPAC measurements during the IPY provide valuable constraints for absorbing aerosol over the Western Arctic, species which are currently poorly simulated over a region that is critically under-sampled.

scholarly journals Absorbing aerosol in the troposphere of the Western Arctic during the 2008 ARCTAS/ARCPAC airborne field campaigns

2011 ◽  
Vol 11 (15) ◽  
pp. 7561-7582 ◽  
Author(s):  
C. S. McNaughton ◽  
A. D. Clarke ◽  
S. Freitag ◽  
V. N. Kapustin ◽  
Y. Kondo ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Carbonaceous Aerosol ◽  
Brown Carbon ◽  
Mass Absorption ◽  
Total Light ◽  
Western Arctic ◽  
Field Campaigns

Abstract. In the spring of 2008 NASA and NOAA funded the ARCTAS and ARCPAC field campaigns as contributions to POLARCAT, a core IPY activity. During the campaigns the NASA DC-8, P-3B and NOAA WP-3D aircraft conducted over 160 h of in-situ sampling between 0.1 and 12 km throughout the Western Arctic north of 55° N (i.e. Alaska to Greenland). All aircraft were equipped with multiple wavelength measurements of aerosol optics, trace gas and aerosol chemistry measurements, as well as direct measurements of the aerosol size distributions and black carbon mass. Late April of 2008 proved to be exceptional in terms of Asian biomass burning emissions transported to the Western Arctic. Though these smoke plumes account for only 11–14 % of the samples within the Western Arctic domain, they account for 42–47 % of the total burden of black carbon. Dust was also commonly observed but only contributes to 4–12 % and 3–8 % of total light absorption at 470 and 530 nm wavelengths above 6 km. Below 6 km, light absorption by carbonaceous aerosol derived from urban/industrial and biomass burning emissions account for 97–99 % of total light absorption by aerosol. Stratifying the data to reduce the influence of dust allows us to determine mass absorption efficiencies for black carbon of 11.2±0.8, 9.5±0.6 and 7.4±0.7 m2 g−1 at 470, 530 and 660 nm wavelengths. These estimates are consistent with 35–80 % enhancements in 530 nm absorption due to clear or slightly absorbing coatings of pure black carbon particulate. Assuming a 1/λ wavelength dependence for BC absorption, and assuming that refractory aerosol (420 °C, τ = 0.1 s) in low-dust samples is dominated by brown carbon, we derive mass absorption efficiencies for brown carbon of 0.83±0.15 and 0.27±0.08 m2 g−1 at 470 and 530 nm wavelengths. Estimates for the mass absorption efficiencies of Asian dust are 0.034 m2 g−1 and 0.017 m2 g−1. However the absorption efficiency estimates for dust are highly uncertain due to the limitations imposed by PSAP instrument noise. In-situ ARCTAS/ARCPAC measurements during the IPY provide valuable constraints for absorbing aerosol over the Western Arctic, species which are currently poorly simulated over a region that is critically under-sampled.

Multi-wavelength measurements of aerosol optical absorption coefficients using a photoacoustic spectrometer

2014 ◽  
Vol 23 (6) ◽  
pp. 064205 ◽  
Author(s):  
Qiang Liu ◽  
Hong-Hua Huang ◽  
Yao Wang ◽  
Gui-Shi Wang ◽  
Zhen-Song Cao ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Coefficients ◽  
Photoacoustic Spectrometer ◽  
Multi Wavelength
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