Search results for "absorptio"

Multi-component gas emission measurements of the active lava lake of Nyiragongo, DR Congo

2017

Between 2007 and 2011 four measurement campaigns (June 2007, July 2010, June 2011, and December 2011) were carried out at the crater rim of Nyiragongo volcano, DR Congo. Nyiragongo is one of the most active volcanoes in Africa. The ground-based remote sensing technique Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS), which uses scattered sunlight, the in-situ Multi-Component Gas Analyzer System (Multi-GAS) and alkaline impregnated filter were simultaneously applied during all field trips. The bromine monoxide to sulfur dioxide (BrO/SO2) and carbon dioxide to sulfur dioxide (CO2/SO2) molar ratios were determined, among other ratios. During the different field trips variati…

Measurements of volcanic SO2 and CO2 fluxes by combined DOAS, Multi-GAS and FTIR observations: a case study from Turrialba and Telica volcanoes

2014

Over the past few decades, substantial progress has been made to overcome the technical difficulties of continuously measuring volcanic SO2 emissions. However, measurements of CO2 emissions still present many difficulties, partly due to the lack of instruments that can directly measure CO2 emissions and partly due to its strong atmospheric background. In order to overcome these difficulties, a commonly taken approach is to combine differential optical absorption spectroscopy (DOAS) by using NOVAC scan-DOAS instruments for continuous measurements of crateric SO2 emissions, and electrochemical/NDIR multi-component gas analyser system (multi-GAS) instruments for measuring CO2/SO2 ratios of exc…

Multicopter measurements of volcanic gas emissions at Masaya (Nicaragua), Turrialba (Costa Rica) and Stromboli (Italy) volcanoes: Applications for vo…

2017

Abstract. Volcanoes are a natural source of several reactive gases (e.g. sulfur and halogen containing species), as well as non-reactive gases (e.g. carbon dioxide). Besides that, halogen chemistry in volcanic plumes might have important impacts on atmospheric chemistry, carbon to sulfur ratios and sulfur dioxide fluxes are important established parameters to gain information on subsurface processes. In this study we demonstrate the successful deployment of a multirotor UAV (quadcopter) system with custom-made lightweight payloads on board for the compositional analysis and gas flux estimation of volcanic plumes. The various applications and their potential with such new measurement strateg…

Volcanic CO2 flux measurement at Campi Flegrei by tunable diode laser absorption spectroscopy

2014

Near-infrared room-temperature Tunable Diode Lasers (TDL) have recently found increased usage in atmospheric chemistry and air monitoring research, but applications in volcanology are still limited to a few examples. Here, we explored the potential of a commercial infrared laser unit (GasFinder 2.0 from Boreal Laser Ltd) for measurement of volcanic CO2 mixing ratios, and ultimately for estimating the volcanic CO2 flux. Our field tests were conducted at Campi Flegrei near Pozzuoli, Southern Italy, where the GasFinder was used during three campaigns in October 2012, January 2013 and May 2013 to repeatedly measure the path-integrated mixing ratios of CO2 along cross-sections of the atmospheric…

First measurement of the Sivers asymmetry for gluons using SIDIS data

2017

The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. It was extracted from measurements of the azimuthal asymmetry of hadrons produced in semi-inclusive deep inelastic scattering of leptons off transversely polarised nucleon targets, and it turned out to be non-zero for quarks. In this letter the evaluation of the Sivers asymmetry for gluons in the same process is presented. The analysis method is based on a Monte Carlo simulation that includes three hard processes: photon-gluon fusion, QCD Compton scattering and leading-order virtual-photon absorption process. The Sivers asymmetries of the three processes are simul…

Modelling molecular iodine emissions in a coastal marine environment: The link to new particle formation

2006

International audience; A model of iodine chemistry in the marine boundary layer (MBL) has been used to investigate the impact of daytime coastal emissions of molecular iodine (I2). The model contains a full treatment of gas-phase iodine chemistry, combined with a description of the nucleation and growth, by condensation and coagulation, of iodine oxide nano-particles. In-situ measurements of coastal emissions of I2 made by the broadband cavity ring-down spectroscopy (BBCRDS) and inductively coupled plasma-mass spectrometry (ICP/MS) techniques are presented and compared to long path differential optical absorption spectroscopy (DOAS) observations of I2 at Mace Head, Ireland. Simultaneous me…

Revisited Dual Luminescence of 2,2′-Dipyridylamine Hydrochloride in Solution and Physical Processes behind It

2018

Ball milling and AlB2 addition effects on the hydrogen sorption properties of the CaH2 + MgB2 system

2010

Among the borohydrides proposed for solid state hydrogen storage,Ca(BH4)2 is particularly interesting because of its favourable thermodynamics and relatively cheap price.Composite systems,whereother species are present in addition to the borohydride,show some advantages in hydrogen sorption properties with respect to the borohydrides alone,despite a reduction of the theoretical storage capacity. We have investigated the milling time influence on the sorption properties of the CaH2 +MgB2 system from which Ca(BH4)2 and MgH2 can be synthesized by hydrogen absorption process.Manometric and calorimetric measurements showed better kinetics forlong time milled samples.We found that the total subst…

Kehon koostumuksen arvioiminen ihopoimumittauksella, biosähköisellä impedanssilla ja kaksienergisen röntgensäteilyn absorptiometrialla

2010

Ojala, Paula Emilia. Kehon koostumuksen arvioiminen ihopoimumittauksella, biosähköisellä impedanssilla ja kaksienergisen röntgensäteilyn absorptiometrialla. Liikuntafysiologian kandidaatintutkielma. Liikuntabiologian laitos, Jyväskylän yliopisto. Syksy 2010. 56s. Tutkimuksen tarkoituksena oli selvittää ovatko kaksienergisen röntgensäteilyn absorptiometrialla (DXA), biosähköisellä impedanssilla (BIA) ja ihopoimujen paksuusmittauksella (SF) arvioidut kehon rasvaprosentit yhtäläisiä. Vedenalaisesta punnitusmenetelmästä on suurimmaksi osaksi jo luovuttu maailmalla ja DXA on todettu luotettavaksi ja tarkaksi menetelmäksi kehon koostumuksen arvioimisessa. Sen vuoksi BIA:n ja SF:n tuloksia verratt…

Superoxide-driven autocatalytic dark production of hydroxyl radicals in the presence of complexes of natural dissolved organic matter and iron

2020

We introduced superoxide as potassium superoxide (KO2) to artificial lake water containing dissolved organic matter (DOM) without or with introduced ferric iron complexes (DOM-Fe), and monitored the production rate of hydroxyl radicals as well as changes in the absorption and fluorescence properties of DOM. The introduction of KO2 decreased the absorption by DOM but increased the spectral slope coefficient of DOM more with complexed ferric Fe than without it. The introduction of KO2 increased the fluorescence of humic-like components in DOM without introduced ferric Fe but resulted in the loss of fluorescence in DOM with introduced ferric Fe. A single introduction of 13 μmol L−1 KO2 produce…