scholarly journals Tunable multi-wavelength absorption in mid-IR region based on a hybrid patterned graphene-hBN structure

2019 ◽  
Vol 27 (16) ◽  
pp. 23576 ◽  
Author(s):  
Guangsheng Deng ◽  
Xianglian Song ◽  
Sina Abedini Dereshgi ◽  
Haiqing Xu ◽  
Koray Aydin
Keyword(s):  
Multi Wavelength ◽  
Wavelength Absorption

scholarly journals Revealing soot maturity based on multi-wavelength absorption/emission measurements in laminar axisymmetric coflow ethylene diffusion flames

2021 ◽  
Vol 227 ◽  
pp. 147-161
Author(s):  
Jérôme Yon ◽  
Juan José Cruz ◽  
Felipe Escudero ◽  
José Morán ◽  
Fengshan Liu ◽  
...  
Keyword(s):  
Diffusion Flames ◽  
Multi Wavelength ◽  
Wavelength Absorption

scholarly journals Comparison of different Aethalometer correction schemes and a reference multi-wavelength absorption technique for ambient aerosol data

2017 ◽  
Vol 10 (8) ◽  
pp. 2837-2850 ◽  
Author(s):  
Jorge Saturno ◽  
Christopher Pöhlker ◽  
Dario Massabò ◽  
Joel Brito ◽  
Samara Carbone ◽  
...  
Keyword(s):  
Wavelength Dependence ◽  
Absorption Coefficients ◽  
Multiple Wavelength ◽  
Filter Loading ◽  
Multi Wavelength ◽  
Online Measurements ◽  
Loading Effects ◽  
Wavelength Absorption ◽  
Absorption Photometer ◽  
Absorption Measurements

Abstract. Deriving absorption coefficients from Aethalometer attenuation data requires different corrections to compensate for artifacts related to filter-loading effects, scattering by filter fibers, and scattering by aerosol particles. In this study, two different correction schemes were applied to seven-wavelength Aethalometer data, using multi-angle absorption photometer (MAAP) data as a reference absorption measurement at 637 nm. The compensation algorithms were compared to five-wavelength offline absorption measurements obtained with a multi-wavelength absorbance analyzer (MWAA), which serves as a multiple-wavelength reference measurement. The online measurements took place in the Amazon rainforest, from the wet-to-dry transition season to the dry season (June–September 2014). The mean absorption coefficient (at 637 nm) during this period was 1.8 ± 2.1 Mm−1, with a maximum of 15.9 Mm−1. Under these conditions, the filter-loading compensation was negligible. One of the correction schemes was found to artificially increase the short-wavelength absorption coefficients. It was found that accounting for the aerosol optical properties in the scattering compensation significantly affects the absorption Ångström exponent (åABS) retrievals. Proper Aethalometer data compensation schemes are crucial to retrieve the correct åABS, which is commonly implemented in brown carbon contribution calculations. Additionally, we found that the wavelength dependence of uncompensated Aethalometer attenuation data significantly correlates with the åABS retrieved from offline MWAA measurements.

Characterization of Particulate From Fires Burning Silicone Fluids

2000 ◽  
Vol 123 (6) ◽  
pp. 1093-1097 ◽  
Author(s):  
Yudaya Sivathanu ◽  
Anthony Hamins ◽  
George Mulholland ◽  
Takashi Kashiwagi ◽  
Robert Buch
Keyword(s):  
Hydrocarbon Flame ◽  
Burner Surface ◽  
Hydrocarbon Flames ◽  
Volume Fractions ◽  
Multi Wavelength ◽  
Wavelength Absorption ◽  
Gravimetric Sampling ◽  
Dominant Part ◽  
Particulate Volume

The optical properties of particulate emitted from fires burning two distinct polydimethylsiloxane fluids (D4 and M2 or MM, where D=CH32SiO and M=CH33SiO2) were obtained using a transmission cell-reciprocal nephelometer in conjunction with gravimetric sampling. The specific absorption coefficient of particulate ash from fires burning D4 and MM is significantly lower than that of particulate soot from an acetylene (hydrocarbon) flame. Scattering is the dominant part of extinction in fires burning the silicone fluids. This is very different from extinction by soot particles in hydrocarbon fires, where absorption is approximately five times greater than scattering. Temperatures and particulate volume fractions along the axis of a silicone fire D4 were measured using multi-wavelength absorption/emission spectroscopy. The structure of the D4 flames is markedly different from hydrocarbon flames. The temperatures and particulate volume fractions very close to the burner surface are much higher than in comparably sized hydrocarbon flames.

scholarly journals Measurement report: Determination of Black Carbon concentration in PM<sub>2.5</sub> fraction by Multi-wavelength absorption black carbon instrument (MABI)

2021 ◽  
Author(s):  
Anna Ryś ◽  
Lucyna Samek
Keyword(s):  
Seasonal Variation ◽  
Black Carbon ◽  
Biomass Burning ◽  
Fossil Fuel ◽  
Environmental Sciences ◽  
Absorption Coefficients ◽  
Multi Wavelength ◽  
Wavelength Absorption ◽  
The Mean

Abstract. The evaluation of black carbon (BC) sources is very important, especially in environmental sciences. This study shows how the contributions of biomass burning and fossil fuel/traffic to PM2.5 mass can be assessed. MABI was used for this purpose and gave the possibility to measure the transmission of light at different wavelengths. Absorption coefficients were calculated from measurements data and recalculated for concentrations of eBC. The samples of PM2.5 fraction were collected from February 1, 2020 to March 27, 2021 every third day in Krakow, Poland (50°04' N, 19°54'47" E). The concentrations of equivalent BC (eBC) from fossil fuel/traffic and biomass burning were in the range 0.82–11.64 μg m−3) and 0.007–0.84 μg m−3, respectively. At the same time, PM2.5 concentrations varied from 3.14 to 55.24 μg m−3. It means that about 18 % of PM2.5 mass belongs to eBC and 11.3 % of this value comes from biomass burning. The eBC contribution is the significant part of PM2.5 mass and we observed seasonal variation of the eBC concentration during the year with the peak in winter. The contribution of biomass burning to PM2.5 mass is more stable during the whole year. The eBC concentration during workdays is a bit higher than during weekend days but biomass burning is similar for both days (work and weekend taken as the mean for the whole period).

scholarly journals Deriving Brown Carbon from Multi-Wavelength Absorption Measurements: Method and Application to AERONET and Surface Observations

2016 ◽  
Author(s):  
Xuan Wang ◽  
Colette L. Heald ◽  
Arthur J. Sedlacek ◽  
Suzane S. de Sá ◽  
Scot T. Martin ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Cape Cod ◽  
Ambient Atmosphere ◽  
Brown Carbon ◽  
Radiative Impact ◽  
Multi Wavelength ◽  
Modelling Studies ◽  
Wavelength Absorption ◽  
Photochemical Aging ◽  
Absorption Measurements

Abstract. The radiative impact of organic aerosols (OA) is a large source of uncertainty in estimating the global direct radiative effect (DRE) of aerosols. This radiative impact includes not only light scattering but also light absorption from a subclass of OA referred to as brown carbon (BrC). However the absorption properties of BrC are poorly understood leading to large uncertainties in modelling studies. To obtain observational constraints from measurements, a simple Absorption Ångström Exponent (AAE) method is often used to separate the contribution of BrC absorption from that of black carbon (BC). However, this attribution method is based on assumptions regarding the spectral dependence of BC that are often violated in the ambient atmosphere. Here we develop a new method that decreases the uncertainties associated with estimating BrC absorption. By applying this method to multi-wavelength absorption aerosol optical depth (AAOD) measurements at AERONET sites worldwide and surface aerosol absorption measurements at multiple ambient sites, we estimate that BrC globally contributes 6–40 % of the absorption at 440 nm. We find that the mass absorption coefficient of OA (OA-MAC) is positively correlated with BC / OA mass ratio. Based on the variability of BC properties and BC / OA emission ratio, we estimate a range of 0.05–1.2 m2/g for OA-MAC at 440 nm. Using the combination of AERONET and OMI UV absorption observations we estimate that the AAE388/440 nm for BrC is generally ~ 4 world-wide, with a smaller value in Europe (< 2). Our analyses of two surface sites (Cape Cod, to the southeast of Boston, and the GoAmazon2014/5 T3 site, to the west of Manaus, Brazil) reveal no significant relationship between BrC absorptivity and photochemical aging in typical urban-influenced conditions. However, the absorption of BrC measured during the biomass burning season near Manaus is found to decrease with photochemical aging with a lifetime of ~ 1 day. This lifetime is comparable to previous observations within a biomass burning plume but much slower than estimated from laboratory studies.

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