Study of the OH and Cl-Initiated Oxidation, IR Absorption Cross-Section, Radiative Forcing, and Global Warming Potential of Four C4-Hydrofluoroethers

2004 ◽  
Vol 38 (21) ◽  
pp. 5567-5576 ◽  
Author(s):  
Nathan Oyaro ◽  
Stig R. Sellevåg ◽  
Claus J. Nielsen
Keyword(s):  
Global Warming ◽  
Cross Section ◽  
Global Warming Potential ◽  
Absorption Cross Section ◽  
Radiative Forcing ◽  
Ir Absorption ◽  
Absorption Cross

scholarly journals An Exploratory Approach Using Regression and Machine Learning in the Analysis of Mass Absorption Cross Section of Black Carbon Aerosols: Model Development and Evaluation

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1185
Author(s):  
Hanyang Li ◽  
Andrew A. May
Keyword(s):  
Support Vector Machine ◽  
Black Carbon ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Radiative Forcing ◽  
Support Vector ◽  
Absorption Cross ◽  
Mass Absorption ◽  
Theoretical Approaches ◽  
Analytical Approaches

Mass absorption cross-section of black carbon (MACBC) describes the absorptive cross-section per unit mass of black carbon, and is, thus, an essential parameter to estimate the radiative forcing of black carbon. Many studies have sought to estimate MACBC from a theoretical perspective, but these studies require the knowledge of a set of aerosol properties, which are difficult and/or labor-intensive to measure. We therefore investigate the ability of seven data analytical approaches (including different multivariate regressions, support vector machine, and neural networks) in predicting MACBC for both ambient and biomass burning measurements. Our model utilizes multi-wavelength light absorption and scattering as well as the aerosol size distributions as input variables to predict MACBC across different wavelengths. We assessed the applicability of the proposed approaches in estimating MACBC using different statistical metrics (such as coefficient of determination (R2), mean square error (MSE), fractional error, and fractional bias). Overall, the approaches used in this study can estimate MACBC appropriately, but the prediction performance varies across approaches and atmospheric environments. Based on an uncertainty evaluation of our models and the empirical and theoretical approaches to predict MACBC, we preliminarily put forth support vector machine (SVM) as a recommended data analytical technique for use. We provide an operational tool built with the approaches presented in this paper to facilitate this procedure for future users.

scholarly journals Photolysis of frozen iodate salts as a source of active iodine in the polar environment

2015 ◽  
Vol 15 (19) ◽  
pp. 27917-27942 ◽  
Author(s):  
O. Gálvez ◽  
M. T. Baeza-Romero ◽  
M. Sanz ◽  
A. Saiz-Lopez
Keyword(s):  
Ir Spectroscopy ◽  
Absorption Coefficient ◽  
Ir Spectra ◽  
Cross Section ◽  
Absorption Cross Section ◽  
Low Temperatures ◽  
Ir Absorption ◽  
Absorption Cross ◽  
Polar Environment ◽  
First Time

Abstract. Reactive halogens play a key role in the oxidation capacity of the polar troposphere. However, sources and mechanisms, particularly those involving active iodine, are still poorly understood. In this paper, the photolysis of an atmospherically relevant frozen iodate salt has been experimentally studied using infrared (IR) spectroscopy. The samples were generated at low temperatures in the presence of different amounts of water. The IR spectra have confirmed that under near-UV/Vis radiation iodate is efficiently photolyzed. The integrated IR absorption coefficient of the iodate anion on the band at 750 cm−1 has been measured to be A = 9.5 × 10−17 cm molec−1. Using this value, a lower limit of the integrated absorption cross section of iodate, in an ammonium frozen salt, has been estimated for the first time at wavelengths relevant for tropospheric studies (σ = 1.1 × 10−20 cm2 nm molec−1 from 300 to 900 nm). According to this, we suggest that the photolysis of iodate in frozen salt can potentially provide a pathway for the release of active iodine to the polar atmosphere.

A Quadruply Azulene-Fused Porphyrin with Intense Near-IR Absorption and a Large Two-Photon Absorption Cross Section

2006 ◽  
Vol 118 (24) ◽  
pp. 4048-4051 ◽  
Author(s):  
Kei Kurotobi ◽  
Kil Suk Kim ◽  
Su Bum Noh ◽  
Dongho Kim ◽  
Atsuhiro Osuka
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Photon Absorption ◽  
Ir Absorption ◽  
Absorption Cross ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Near Ir

scholarly journals Photoelectric absorption cross section of silicon near the bandgap from room temperature to sub-Kelvin temperature

AIP Advances ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 025120
Author(s):  
C. Stanford ◽  
M. J. Wilson ◽  
B. Cabrera ◽  
M. Diamond ◽  
N. A. Kurinsky ◽  
...  
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Room Temperature ◽  
Absorption Cross ◽  
Photoelectric Absorption

scholarly journals Ultraviolet Absorption Cross-Sections of Ammonia at Elevated Temperatures for Nonintrusive Quantitative Detection in Combustion Environments

2021 ◽  
pp. 000370282199044
Author(s):  
Wubin Weng ◽  
Shen Li ◽  
Marcus Aldén ◽  
Zhongshan Li
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absorption Cross Section ◽  
Elevated Temperatures ◽  
Uv Absorption ◽  
Energy Utilization ◽  
Quantitative Detection ◽  
Absorption Cross ◽  
Hot Gas

Ammonia (NH3) is regarded as an important nitrogen oxides (NOx) precursor and also as an effective reductant for NOx removal in energy utilization through combustion, and it has recently become an attractive non-carbon alternative fuel. To have a better understanding of thermochemical properties of NH3, accurate in situ detection of NH3 in high temperature environments is desirable. Ultraviolet (UV) absorption spectroscopy is a feasible technique. To achieve quantitative measurements, spectrally resolved UV absorption cross-sections of NH3 in hot gas environments at different temperatures from 295 K to 590 K were experimentally measured for the first time. Based on the experimental results, vibrational constants of NH3 were determined and used for the calculation of the absorption cross-section of NH3 at high temperatures above 590 K using the PGOPHER software. The investigated UV spectra covered the range of wavelengths from 190 nm to 230 nm, where spectral structures of the [Formula: see text] transition of NH3 in the umbrella bending mode, v2, were recognized. The absorption cross-section was found to decrease at higher temperatures. For example, the absorption cross-section peak of the (6, 0) vibrational band of NH3 decreases from ∼2 × 10−17 to ∼0.5 × 10−17 cm2/molecule with the increase of temperature from 295 K to 1570 K. Using the obtained absorption cross-section, in situ nonintrusive quantification of NH3 in different hot gas environments was achieved with a detection limit varying from below 10 parts per million (ppm) to around 200 ppm as temperature increased from 295 K to 1570 K. The quantitative measurement was applied to an experimental investigation of NH3 combustion process. The concentrations of NH3 and nitric oxide (NO) in the post flame zone of NH3–methane (CH4)–air premixed flames at different equivalence ratios were measured.

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