scholarly journals Light absorption efficiency and the package effect in the leaves of the seagrass Thalassia testudinum

2005 ◽  
Vol 289 ◽  
pp. 141-150 ◽  
Author(s):  
S Enríquez
Keyword(s):  
Light Absorption ◽  
Thalassia Testudinum ◽  
Absorption Efficiency ◽  
Package Effect

scholarly journals Development of Visible-Light-Driven Rh–TiO2–CeO2 Hybrid Photocatalysts for Hydrogen Production

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 848
Author(s):  
Jong-Wook Hong
Keyword(s):  
Hydrogen Production ◽  
Visible Light ◽  
Light Absorption ◽  
Photocatalytic Performance ◽  
Environmental Issues ◽  
Absorption Efficiency ◽  
Low Light ◽  
Practical Applications ◽  
Visible Light Driven ◽  
Poor Stability

Visible-light-driven hydrogen production through photocatalysis has attracted enormous interest owing to its great potential to address energy and environmental issues. However, photocatalysis possesses several limitations to overcome for practical applications, such as low light absorption efficiency, rapid charge recombination, and poor stability of photocatalysts. Here, the preparation of efficient noble metal–semiconductor hybrid photocatalysts for photocatalytic hydrogen production is presented. The prepared ternary Rh–TiO2–CeO2 hybrid photocatalysts exhibited excellent photocatalytic performance toward the hydrogen production reaction compared with their counterparts, ascribed to the synergistic combination of Rh, TiO2, and CeO2.

scholarly journals Phytoplankton light absorption and the package effect in relation to photosynthetic and photoprotective pigments in the northern tip of Antarctic Peninsula

2017 ◽  
Vol 122 (9) ◽  
pp. 7344-7363 ◽  
Author(s):  
Amabile Ferreira ◽  
Áurea M. Ciotti ◽  
Carlos Rafael B. Mendes ◽  
Julia Uitz ◽  
Annick Bricaud
Keyword(s):  
Antarctic Peninsula ◽  
Light Absorption ◽  
Package Effect

Brown carbon aerosol in urban Beijing: Significant contributions from biomass burning and secondary formation

2020 ◽  
Author(s):  
Ting Wang ◽  
Rujin Huang ◽  
Lu Yang ◽  
Wei Yuan ◽  
Yuquan Gong
Keyword(s):  
Biomass Burning ◽  
Light Absorption ◽  
Coal Combustion ◽  
Absorption Efficiency ◽  
Traffic Emission ◽  
Brown Carbon ◽  
Factorization Model ◽  
Secondary Formation ◽  
Vis Spectroscopy ◽  
The Impact

<p>Atmospheric brown carbon (BrC) has significant impact on Earth’s radiative budget. However, due to our very limited knowledge about the relationship between BrC light absorption and the associated sources, the estimation for radiative effects of BrC is still largely constrained. In this study, we combine ultraviolet−visible (UV−vis) spectroscopy measurements and chemical analyses of BrC samples collected from January to December 2015 in urban Beijing, to investigated the sources of atmospheric BrC. The multiple liner regression model was applied to apportion the contributions of individual primary and secondary organic aerosol (OA) source components to light absorption of BrC. Our results indicated that biomass burning emission and secondary formation are highly absorbing up to 500 nm, and their contributions increased with the wavelengths. In contrast, the contribution of traffic emission and coal combustion to total absorption decreased with the wavelength and the large contributions were mostly found at shorter wavelengths. Then the mass absorption efficiency (MAE) of major light-absorbing components were estimated, which can provide a support to estimate the impact of BrC from these sources on the climate. The positive matrix factorization model were also used to verify the contributions of different source components of BrC absorption at 365 nm. The results consistently demonstrate that the biomass burning and secondary formation contributes significantly to the overall absorption, followed by coal combustion and traffic emission.</p>

Light absorption properties, chromophore composition and sources of brown carbon aerosol in Xi’an, Northwest China

2020 ◽  
Author(s):  
Ru-Jin Huang ◽  
Wei Yuan ◽  
Lu Yang ◽  
Jie Guo ◽  
Jing Duan ◽  
...  
Keyword(s):  
Light Absorption ◽  
Coal Combustion ◽  
Radiative Forcing ◽  
Northwest China ◽  
Absorption Efficiency ◽  
Vehicular Emissions ◽  
Absorption Properties ◽  
Seasonal Differences ◽  
Brown Carbon ◽  
The Impact

<p>The impact of brown carbon aerosol (BrC) on the Earth’s radiative forcing balance has been widely recognized but remains uncertain, mainly because the relationships among BrC sources, chromophores, and optical properties of aerosol are poorly understood (Feng et al., 2013; Laskin et al., 2015). In this work, the light absorption properties and chromophore composition of BrC were investigated for samples collected in Xi’an, Northwest China from 2015 to 2016. Both absorption Ångström exponent and mass absorption efficiency show distinct seasonal differences, which could be attributed to the differences in sources and chromophore composition of BrC. Three groups of light-absorbing organics were found to be important BrC chromophores, including those show multiple absorption peaks at wavelength > 350 nm (12 polycyclic aromatic hydrocarbons and their derivatives) and those show single absorption peak at wavelength < 350 nm (10 nitrophenols and nitrosalicylic acids and 3 methoxyphenols). These measured BrC chromophores show distinct seasonal differences and contribute on average about 1.1% and 3.3% of light absorption of methanol-soluble BrC at 365 nm in summer and winter, respectively, about 7 and 5 times higher than the corresponding mass fractions in total organic carbon. The sources of BrC were resolved by positive matrix factorization (PMF) using these chromophores instead of commonly used non-light absorbing organic markers as model inputs. Our results show that in spring vehicular emissions and secondary formation are major sources of BrC (~70%), in fall coal combustion and vehicular emissions are major sources (~70%), in winter biomass burning and coal combustion become major sources (~80%), while in summer secondary BrC dominates (~60%).</p><p> </p><p>References:</p><p>Feng, Y., V. Ramanathan, and V. R. Kotamarthi: Brown carbon: A significant atmospheric absorber of solar radiation?, Atmos. Chem. Phys., 13, 8607-8621, doi:10.5194/acp-13-8607-2013, 2013.</p><p>Laskin, A., J. Laskin, and S. A. Nizkorodov: Chemistry of atmospheric brown carbon, Chem. Rev., 115, 4335-4382, doi:10.1021/cr5006167, 2015.</p>

scholarly journals Mass absorption efficiency of elemental carbon and water-soluble organic carbon in Beijing, China

2011 ◽  
Vol 11 (22) ◽  
pp. 11497-11510 ◽  
Author(s):  
Y. Cheng ◽  
K.-B. He ◽  
M. Zheng ◽  
F.-K. Duan ◽  
Z.-Y. Du ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Light Absorption ◽  
Elemental Carbon ◽  
Organic Aerosol ◽  
Absorption Efficiency ◽  
Water Soluble ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Mass Absorption Efficiency

Abstract. The mass absorption efficiency (MAE) of elemental carbon (EC) in Beijing was quantified using a thermal-optical carbon analyzer. The MAE measured at 632 nm was 8.45±1.71 and 9.41±1.92 m2 g−1 during winter and summer respectively. The daily variation of MAE was found to coincide with the abundance of organic carbon (OC), especially the OC to EC ratio, perhaps due to the enhancement by coating with organic aerosol (especially secondary organic aerosol, SOA) or the artifacts resulting from the redistribution of liquid-like organic particles during the filter-based absorption measurements. Using a converting approach that accounts for the discrepancy caused by measurements methods of both light absorption and EC concentration, previously published MAE values were converted to the equivalent-MAE, which is the estimated value if using the same measurement methods as used in this study. The equivalent-MAE was found to be much lower in the regions heavily impacted by biomass burning (e.g., below 2.7 m2 g−1 for two Indian cities). Results from source samples (including diesel exhaust samples and biomass smoke samples) also demonstrated that emissions from biomass burning would decrease the MAE of EC. Moreover, optical properties of water-soluble organic carbon (WSOC) in Beijing were presented. Light absorption by WSOC exhibited strong wavelength (λ) dependence such that absorption varied approximately as λ−7, which was characteristic of the brown carbon spectra. The MAE of WSOC (measured at 365 nm) was 1.79±0.24 and 0.71±0.20 m2 g−1 during winter and summer respectively. The large discrepancy between the MAE of WSOC during winter and summer was attributed to the difference in the precursors of SOA such that anthropogenic volatile organic compounds (AVOCs) should be more important as the precursors of SOA in winter. The MAE of WSOC in Beijing was much higher than results from the southeastern United States which were obtained using the same method as used in this study, perhaps due to the stronger emissions of biomass burning in China.

scholarly journals Quantifying black carbon light absorption enhancement by a novel statistical approach

2017 ◽  
Author(s):  
Cheng Wu ◽  
Dui Wu ◽  
Jian Zhen Yu
Keyword(s):  
Black Carbon ◽  
Light Absorption ◽  
Seasonal Pattern ◽  
Absorption Efficiency ◽  
Absorption Enhancement ◽  
Hygroscopic Growth ◽  
Pearl River Delta Region ◽  
Coating Materials ◽  
Air Masses ◽  
The Pearl River

Abstract. Black carbon (BC) particles in the atmosphere can absorb more light when coated by non-absorbing or weakly absorbing materials during atmospheric aging, due to the lensing effect. In this study, the light absorption enhancement factor, Eabs, was quantified using one year's measurement of mass absorption efficiency (MAE) in the Pearl River Delta region (PRD). A new approach for calculating primary MAE (MAEp), the key for Eabs estimation, is demonstrated using the Minimum R Squared (MRS) method, exploring the inherent source independency between BC and its coating materials. The annual average Eabs is found to be 1.52, exhibiting a clear seasonal pattern with higher values in summer and lower in the winter. Elevated Eabs in the rainy summer season is likely associated with aged air masses dominating from marine origin, along with long-range transport of biomass burning influenced air masses from Southeast Asia. Eabs induced by hygroscopic growth at elevated RH could be as high as 1.3. Core-shell Mie simulations along with measured Eabs and Angstrom absorption exponent (AAE) constraints suggest that in the PRD, the coating materials are unlikely to be dominated by brown carbon and the coating thickness is higher in the rainy season than the dry season. A negative correlation is found between AAE470–660 and RH, suggesting a dominant particle size of Dcore = 130 nm and Dshell/Dcore range of 2 to 4.

scholarly journals On the attribution of black and brown carbon light absorption using the Ångström exponent

2013 ◽  
Vol 13 (6) ◽  
pp. 15493-15515 ◽  
Author(s):  
D. A. Lack ◽  
J. M. Langridge
Keyword(s):  
Black Carbon ◽  
Light Absorption ◽  
Absorption Efficiency ◽  
Potential Range ◽  
Brown Carbon ◽  
Angstrom Exponent ◽  
Ångström Exponent ◽  
Absorbing Material ◽  
Visible Wavelengths ◽  
Ångstrom Exponent

Abstract. The absorption Ångström exponent (åAbs) of black carbon (BC), or BC internally mixed with non-absorbing material (BCInt), is often used to differentiate the contribution of black carbon, dust and brown carbon to light absorption at low-visible wavelengths. This attribution method contains assumptions with uncertainties that have not been formally assessed. We show that the potential range of åAbs for BC (or BCInt) in the atmosphere can reasonably lead to +7% to −22% uncertainty in BC (or BCInt) absorption at 404nm derived from measurements made at 658 nm. These uncertainties propagate to errors in the attributed absorption and mass absorption efficiency (MAE) of brown carbon (BrC). For data collected during a biomass-burning event, the mean uncertainty in MAE at 404 nm attributed to BrC using the åAbs method was found to be 34%. In order to yield attributed BrC absorption uncertainties of ±33%, 23% to 41% of total absorption must be sourced from BrC. In light of the potential for introducing significant and poorly constrained errors, we caution against the universal application of the åAbs attribution method.

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