Browsing by Subject "GAS"

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  • Feher, O.; Juvela, M.; Lunttila, T.; Montillaud, J.; Ristorcelli, I.; Zahorecz, S.; Toth, L. V. (2017)
    Context. The physical state of cold cloud clumps has a great impact on the process and efficiency of star formation and the masses of the forming stars inside these objects. The sub-millimetre survey of the Planck space observatory and the far-infrared follow-up mapping of the Herschel space telescope provide an unbiased, large sample of these cold objects. Aims. We have observed (CO)-C-12(1-0) and (CO)-C-13(1-0) emission in 35 high-density clumps in 26 Herschel fields sampling different environments in the Galaxy. Here, we aim to derive the physical properties of the objects and estimate their gravitational stability. Methods. The densities and temperatures of the clumps were calculated from both the dust continuum and the molecular line data. Kinematic distances were derived using (CO)-C-13(1-0) line velocities to verify previous distance estimates and the sizes and masses of the objects were calculated by fitting 2D Gaussian functions to their optical depth distribution maps on 250 mu m. The masses and virial masses were estimated assuming an upper and lower limit on the kinetic temperatures and considering uncertainties due to distance limitations. Results. The derived excitation temperatures are between 8.5-19.5 K, and for most clumps between 10 15 K, while the Herschel-derived dust colour temperatures are more uniform, between 12 16 K. The sizes (0.1-3 pc), (CO)-C-13 column densities (0.5-44 x 10(15) cm(-2)) and masses (from less than 0.1 M-circle dot to more than 1500 M-circle dot) of the objects all span broad ranges. We provide new kinematic distance estimates, identify gravitationally bound or unbound structures and discuss their nature. Conclusions. The sample contains objects on a wide scale of temperatures, densities and sizes. Eleven gravitationally unbound clumps were found, many of them smaller than 0.3 pc, but large, parsec-scale clouds with a few hundred solar masses appear as well. Colder clumps have generally high column densities but warmer objects appear at both low and higher column densities. The clump column densities derived from the line and dust observations correlate well, but are heavily affected by uncertainties of the dust properties, varying molecular abundances and optical depth effects.
  • Lu, Yiqun; Yan, Chao; Fu, Yueyun; Chen, Yan; Liu, Yiliang; Yang, Gan; Wang, Yuwei; Bianchi, Federico; Chu, Biwu; Zhou, Ying; Yin, Rujing; Baalbaki, Rima; Garmash, Olga; Deng, Chenjuan; Wang, Weigang; Liu, Yongchun; Petäjä, Tuukka; Kerminen, Veli-Matti; Jiang, Jingkun; Kulmala, Markku; Wang, Lin (2019)
    Gaseous sulfuric acid (H2SO4) is known as one of the key precursors for atmospheric new particle formation (NPF) processes, but its measurement remains challenging. Therefore, a proxy method that is able to derive gaseous sulfuric acid concentrations from parameters that can be measured relatively easily and accurately is highly desirable for the atmospheric chemistry community. Although such methods are available for clean atmospheric environments, a proxy that works well in a polluted atmosphere, such as that found in Chinese megacities, is yet to be developed. In this study, the gaseous sulfuric acid concentration was measured in February-March 2018, in urban Beijing using a nitrate based -long time-of-flight chemical ionization mass spectrometer (LToF-CIMS). A number of atmospheric parameters were recorded concurrently including the ultraviolet radiation B (UVB) intensity, the concentrations of O-3, NOx (sum of NO and NO2), SO2, and HONO, and aerosol particle number size distributions. A proxy for atmospheric daytime gaseous sulfuric acid concentration was derived via a statistical analysis method using the UVB intensity, [SO2], the condensation sink (CS), [O-3], and [HONO] (or [NOx]) as the predictor variables, where square brackets denote the concentrations of the corresponding species. In this proxy method, we considered the formation of gaseous sulfuric acid from reactions of SO2 and OH radicals during the daytime, and the loss of gaseous sulfuric acid due to its condensation onto the preexisting particles. In addition, we explored the formation of OH radicals from the conventional gas-phase photochemistry using O-3 as a proxy and from the photolysis of HONO using HONO (and subsequently NOx) as a proxy. Our results showed that the UVB intensity and [SO2] are dominant factors in the production of gaseous sulfuric acid, and that the simplest proxy could be constructed with the UVB intensity and [SO2] alone. When the OH radical production from both homogenously and heterogeneously formed precursors were considered, the relative errors were reduced by up to 20 %.
  • Liebmann, Jonathan; Sobanski, Nicolas; Schuladen, Jan; Karu, Einar; Hellen, Heidi; Hakola, Hannele; Zha, Qiaozhi; Ehn, Mikael; Riva, Matthieu; Heikkinen, Liine; Williams, Jonathan; Fischer, Horst; Lelieyeld, Jos; Crowley, John N. (2019)
    The formation of alkyl nitrates in various oxidation processes taking place throughout the diel cycle can represent an important sink of reactive nitrogen and mechanism for chain termination in atmospheric photo-oxidation cycles. The low-volatility alkyl nitrates (ANs) formed from biogenic volatile organic compounds (BVOCs), especially terpenoids, enhance rates of production and growth of secondary organic aerosol. Measurements of the NO3 reactivity and the mixing ratio of total alkyl nitrates (6 ANs) in the Finnish boreal forest enabled assessment of the relative importance of NO3-, O-3- and OH-initiated formation of alkyl nitrates from BVOCs in this environment. The high reactivity of the forest air towards NO3 resulted in reactions of the nitrate radical, with terpenes contributing substantially to formation of ANs not only during the night but also during daytime. Overall, night-time reactions of NO3 accounted for 49% of the local production rate of ANs, with contributions of 21 %, 18% and 12% for NO3, OH and O-3 during the day. The lifetimes of the gas-phase ANs formed in this environment were on the order of 2 h due to efficient uptake to aerosol (and dry deposition), resulting in the transfer of reactive nitrogen from anthropogenic sources to the forest ecosystem.
  • Tatematsu, Ken'ichi; Liu, Tie; Kim, Gwanjeong; Yi, Hee-Weon; Lee, Jeong-Eun; Hirano, Naomi; Liu, Sheng-Yuan; Ohashi, Satoshi; Sanhueza, Patricio; Di Francesco, James; Evans, Neal J.; Fuller, Gary A.; Kandori, Ryo; Choi, Minho; Kang, Miju; Feng, Siyi; Hirota, Tomoya; Sakai, Takeshi; Lu, Xing; Lu'o'ng, Quang Nguyen; Thompson, Mark A.; Wu, Yuefang; Li, Di; Kim, Kee-Tae; Wang, Ke; Ristorcelli, Isabelle; Juvela, Mika; Toth, L. Viktor (2020)
    We mapped two molecular cloud cores in the Orion A cloud with the 7 m Array of the Atacama Compact Array (ACA) of the Atacama Large Millimeter/submillimeterArray (ALMA) and with the Nobeyama 45 m radio telescope. These cores have bright N2D+ emission in single-pointing observations with the Nobeyama 45 m radio telescope, have a relatively high deuterium fraction, and are thought to be close to the onset of star formation. One is a star-forming core, and the other is starless. These cores are located along filaments observed in N2H+ and show narrow line widths of 0.41 km s(-1) and 0.45 km s(-1) in N2D+, respectively, with the Nobeyama 45 m telescope. Both cores were detected with the ALMA ACA 7 m Array in the continuum and molecular lines at Band 6. The starless core G211 shows a clumpy structure with several sub-cores, which in turn show chemical differences. Also, the sub-cores in G211 have internal motions that are almost purely thermal. The starless sub-core G211D, in particular, shows a hint of the inverse P Cygni profile, suggesting infall motion. The star-forming core G210 shows an interesting spatial feature of two N2D+ peaks of similar intensity and radial velocity located symmetrically with respect to the single dust continuum peak. One interpretation is that the two N2D+ peaks represent an edge-on pseudo-disk. The CO outflow lobes, however, are not directed perpendicular to the line connecting both N2D+ peaks.
  • D'Ambro, Emma L.; Schobesberger, Siegfried; Gaston, Cassandra J.; Lopez-Hilfiker, Felipe D.; Lee, Ben H.; Liu, Jiumeng; Zelenyuk, Alla; Bell, David; Cappa, Christopher D.; Helgestad, Taylor; Li, Ziyue; Guenther, Alex; Wang, Jian; Wise, Matthew; Caylor, Ryan; Surratt, Jason D.; Riedel, Theran; Hyttinen, Noora; Salo, Vili-Taneli; Hasan, Galib; Kurten, Theo; Shilling, John E.; Thornton, Joel A. (2019)
    We present measurements utilizing the Filter Inlet for Gases and Aerosols (FIGAERO) applied to chamber measurements of isoprene-derived epoxydiol (IEPOX) reactive uptake to aqueous acidic particles and associated secondary organic aerosol (SOA) formation. Similar to recent field observations with the same instrument, we detect two molecular components desorbing from the IEPOX SOA in high abundance: C5H12O4 and C5H10O3. The thermal desorption signal of the former, presumably 2-methyltetrols, exhibits two distinct maxima, suggesting it arises from at least two different SOA components with significantly different effective volatilities. Isothermal evaporation experiments illustrate that the most abundant component giving rise to C5H12O4 is semi-volatile, undergoing nearly complete evaporation within 1 h while the second, less volatile component remains unperturbed and even increases in abundance. We thus confirm, using controlled laboratory studies, recent analyses of ambient SOA measurements showing that IEPOX SOA is of very low volatility and commonly measured IEPOX SOA tracers such as C5H12O4 and C5H10O3, presumably 2-methyltetrols and C5-alkene triols or 3-MeTHF-3,4-diols, result predominantly from thermal decomposition in the FIGAERO-CIMS. We infer that other measurement techniques using thermal desorption or prolonged heating for analysis of SOA components may also lead to reported 2-methyltetrols and C5-alkene triols or 3-MeTHF-3,4-diol structures. We further show that IEPOX SOA volatility continues to evolve via acidity-enhanced accretion chemistry on the timescale of hours, potentially involving both 2-methyltetrols and organosulfates.
  • Riva, Matthieu; Heikkinen, Liine; Bell, David M.; Peräkylä, Otso; Zha, Qiaozhi; Rissanen, Matti; Imre, D.; Petäjä, Tuukka; Thornton, Joel; Zelenyuk, Alla; Ehn, Mikael (2019)
    Secondary organic aerosol (SOA) is known to impact both climate and air quality, yet molecular-level composition measurements remain challenging, hampering our understanding of SOA formation and evolution. Here, we reveal the importance of underestimated reaction pathways for the (trans) formation of SOA from monoterpenes, one of the largest SOA precursors globally. Utilizing mass spectrometric techniques to achieve a comprehensive characterization of molecular-level changes in the SOA, we were able to link the appearance of high-molecular weight (HMW) organic molecules to the concentration and level of neutralization of particulate sulfate. Interestingly, this oligomerization coincided with a decrease of highly oxygenated molecules (HOMs). Our findings highlight the role of particle-phase processing, and the underestimated importance of sulfate aerosol for monoterpene-SOA formation. The observations of these processes directly in the atmosphere reveal the need to account for the formation of HMW oligomers to fully understand the physicochemical properties of organic aerosol.
  • Lopez-Hilfiker, Felipe D.; Iyer, Siddharth; Mohr, Claudia; Lee, Ben H.; D'Ambro, Emma L.; Kurten, Theo; Thornton, Joel A. (2016)
    The sensitivity of a chemical ionization mass spectrometer (ions formed per number density of analytes) is fundamentally limited by the collision frequency between reagent ions and analytes, known as the collision limit, the ion-molecule reaction time, and the transmission efficiency of product ions to the detector. We use the response of a time-of-flight chemical ionization mass spectrometer (ToF-CIMS) to N2O5, known to react with iodide at the collision limit, to constrain the combined effects of ion-molecule reaction time, which is strongly influenced by mixing and ion losses in the ion-molecule reaction drift tube. A mass spectrometric voltage scanning procedure elucidates the relative binding energies of the ion adducts, which influence the transmission efficiency of molecular ions through the electric fields within the vacuum chamber. Together, this information provides a critical constraint on the sensitivity of a ToF-CIMS towards a wide suite of routinely detected multifunctional organic molecules for which no calibration standards exist. We describe the scanning procedure and collision limit determination, and we show results from the application of these constraints to the measurement of organic aerosol composition at two different field locations.
  • Farahi, Arya; Mulroy, Sarah L.; Evrard, August E.; Smith, Graham P.; Finoguenov, Alexis; Bourdin, Herve; Carlstrom, John E.; Haines, Chris P.; Marrone, Daniel P.; Martino, Rossella; Mazzotta, Pasquale; O'Donnell, Christine; Okabe, Nobuhiro (2019)
    The largest clusters of galaxies in the Universe contain vast amounts of dark matter, plus baryonic matter in two principal phases, a majority hot gas component and a minority cold stellar phase comprising stars, compact objects, and low-temperature gas. Hydrodynamic simulations indicate that the highest-mass systems retain the cosmic fraction of baryons, a natural consequence of which is anti-correlation between the masses of hot gas and stars within dark matter halos of fixed total mass. We report observational detection of this anti-correlation based on 4 elements of a 9 x 9-element covariance matrix for nine cluster properties, measured from multi-wavelength observations of 41 clusters from the Local Cluster Substructure Survey. These clusters were selected using explicit and quantitative selection rules that were then encoded in our hierarchical Bayesian model. Our detection of anti-correlation is consistent with predictions from contemporary hydrodynamic cosmological simulations that were not tuned to reproduce this signal.
  • Juvela, Mika; Neha, Sharma; Mannfors, Emma; Saajasto, Mika; Ysard, Nathalie; Pelkonen, Veli-Matti (2020)
    Context. LDN 1642 is a rare example of a star-forming, high-latitude molecular cloud. The dust emission of LDN 1642 has already been studied extensively in the past, but its location also makes it a good target for studies of light scattering.Aims. We wish to study the near-infrared (NIR) light scattering in LDN 1642, its correlation with the cloud structure, and the ability of dust models to simultaneously explain observations of sub-millimetre dust emission, NIR extinction, and NIR scattering.Methods. We used observations made with the HAWK-I instrument to measure the NIR surface brightness and extinction in LDN 1642. These data were compared with Herschel observations of dust emission and, with the help of radiative transfer modelling, with the predictions calculated for different dust models.Results. We find, for LDN 1642, an optical depth ratio tau (250 mu m)/tau (J) approximate to 10(-3), confirming earlier findings of enhanced sub-millimetre emissivity. The relationships between the column density derived from dust emission and the NIR colour excesses are linear and consistent with the shape of the standard NIR extinction curve. The extinction peaks at A(J) = 2.6 mag, and the NIR surface brightness remains correlated with N(H-2) without saturation. Radiative transfer models are able to fit the sub-millimetre data with any of the tested dust models. However, these predict an NIR extinction that is higher and an NIR surface brightness that is lower than based on NIR observations. If the dust sub-millimetre emissivity is rescaled to the observed value of tau (250 mu m)/tau (J), dust models with high NIR albedo can reach the observed level of NIR surface brightness. The NIR extinction of the models tends to be higher than in the direct extinction measurements, which is also reflected in the shape of the NIR surface brightness spectra.Conclusions. The combination of emission, extinction, and scattering measurements provides strong constraints on dust models. The observations of LDN 1642 indicate clear dust evolution, including a strong increase in the sub-millimetre emissivity, which has not been fully explained by the current dust models yet.
  • Neitola, Kimmo; Brus, David; Makkonen, Ulla; Sipila, Mikko; Lihavainen, Heikki; Kulmala, Markku (2014)
  • Harju, Jorma; Pineda, Jaime E.; Vasyunin, Anton; Caselli, Paola; Offner, Stella S. R.; Goodman, Alyssa A.; Juvela, Mika; Sipilä, Olli; Faure, Alexandre; Le Gal, Romane; Hily-Blant, Pierre; Alves, Joao; Bizzocchi, Luca; Burkert, Andreas; Chen, Hope; Friesen, Rachel K.; Guesten, Rolf; Myers, Philip C.; Punanova, Anna; Rist, Claire; Rosolowsky, Erik; Schlemmer, Stephan; Shirley, Yancy; Spezzano, Silvia; Vastel, Charlotte; Wiesenfeld, Laurent (2020)
    We present Atacama Large Millimeter/submillimeter Array maps of the starless molecular cloud core Ophiuchus/H-MM1 in the lines of deuterated ammonia (ortho-NH2D), methanol (CH3OH), and sulfur monoxide (SO). The dense core is seen in NH2D emission, whereas the CH3OH and SO distributions form a halo surrounding the core. Because methanol is formed on grain surfaces, its emission highlights regions where desorption from grains is particularly efficient. Methanol and sulfur monoxide are most abundant in a narrow zone that follows the eastern side of the core. This side is sheltered from the stronger external radiation field coming from the west. We show that photodissociation on the illuminated side can give rise to an asymmetric methanol distribution but that the stark contrast observed in H-MM1 is hard to explain without assuming enhanced desorption on the shaded side. The region of the brightest emission has a wavy structure that rolls up at one end. This is the signature of Kelvin-Helmholtz instability occurring in sheared flows. We suggest that in this zone, methanol and sulfur are released as a result of grain-grain collisions induced by shear vorticity.
  • Sahyoun, Maher; Freney, Evelyn; Brito, Joel; Duplissy, Jonathan; Gouhier, Mathieu; Colomb, Aurélie; Dupuy, Regis; Bourianne, Thierry; Nowak, John B.; Yan, Chao; Petäjä, Tuukka; Kulmala, Markku; Schwarzenboeck, Alfons; Planche, Céline; Sellegri, Karine (2019)
    Abstract Volcanic emissions can significantly affect the Earth's radiation budget by emitting aerosol particles and gas-phase species that can result in the new particle formation (NPF). These particles can scatter solar radiation or modify cloud properties, with consequences on health, weather, and climate. To our knowledge, this is the first dedicated study detailing how gas-phase precursors emitted from volcanic plumes can influence the NPF. A series of airborne measurements were performed around the Etna and Stromboli volcanoes within the framework of the CLerVolc and STRAP projects. The ATR-42 aircraft was equipped with a range of instrumentation allowing the measurement of particle number concentration in diameter range above 2.5 nm, and gaseous species to investigate the aerosol dynamics and the processes governing the NPF and their growth within the volcanic plumes. We demonstrate that NPF occurs within the volcanic plumes in the Free Troposphere (FT) and Boundary Layer (BL). Typically, the NPF events were more pronounced in the FT, where the condensational sink was up to two orders of magnitude smaller and the temperature was ~20°C lower than in the BL. Within the passive volcanic plume, the concentration of sulfur dioxide, sulfuric acid, and N2.5 were as high as 92 ppbV, 5.65?108 and 2.4?105 cm?3, respectively. Using these measurements, we propose a new parameterization for NPF rate (J2.5) within the passive volcanic plume in the FT. These results can be incorporated into mesoscale models to better assess the impact of the particle formed by natural processes, i.e. volcanic plumes, on climate.
  • Zhao, Junlei; Cao, Lu; Palmer, Richard E.; Nordlund, Kai; Djurabekova, Flyura (2017)
    In this paper, we study the mechanisms of growth of Ag nanoclusters in a solid Ar matrix and the emission of these nanoclusters from the matrix by a combination of experimental and theoretical methods. The molecular dynamics simulations show that the cluster growth mechanism can be described as "thermal spike-enhanced clustering" in multiple sequential ion impact events. We further show that experimentally observed large sputtered metal clusters cannot be formed by direct sputtering of Ag mixed in the Ar. Instead, we describe the mechanism of emission of the metal nanocluster that, at first, is formed in the cryogenic matrix due to multiple ion impacts, and then is emitted as a result of the simultaneous effects of interface boiling and spring force. We also develop an analytical model describing this size-dependent cluster emission. The model bridges the atomistic simulations and experimental time and length scales, and allows increasing the controllability of fast generation of nanoclusters in experiments with a high production rate.
  • Lee, Ben H.; Mohr, Claudia; Lopez-Hilfiker, Felipe D.; Lutz, Anna; Hallquist, Mattias; Lee, Lance; Romer, Paul; Cohen, Ronald C.; Iyer, Siddharth; Kurten, Theo; Hu, Weiwei; Day, Douglas A.; Campuzano-Jost, Pedro; Jimenez, Jose L.; Xu, Lu; Ng, Nga Lee; Guo, Hongyu; Weber, Rodney J.; Wild, Robert J.; Brown, Steven S.; Koss, Abigail; de Gouw, Joost; Olson, Kevin; Goldstein, Allen H.; Seco, Roger; Kim, Saewung; McAvey, Kevin; Shepson, Paul B.; Starn, Tim; Baumann, Karsten; Edgerton, Eric S.; Liu, Jiumeng; Shilling, John E.; Miller, David O.; Brune, William; Schobesberger, Siegfried; D'Ambro, Emma L.; Thornton, Joel A. (2016)
    Speciated particle-phase organic nitrates (pONs) were quantified using online chemical ionization MS during June and July of 2013 in rural Alabama as part of the Southern Oxidant and Aerosol Study. A large fraction of pONs is highly functionalized, possessing between six and eight oxygen atoms within each carbon number group, and is not the common first generation alkyl nitrates previously reported. Using calibrations for isoprene hydroxynitrates and the measured molecular compositions, we estimate that pONs account for 3% and 8% of total submicrometer organic aerosol mass, on average, during the day and night, respectively. Each of the isoprene-and monoterpenes-derived groups exhibited a strong diel trend consistent with the emission patterns of likely biogenic hydrocarbon precursors. An observationally constrained diel box model can replicate the observed pON assuming that pONs (i) are produced in the gas phase and rapidly establish gas-particle equilibrium and (ii) have a short particle-phase lifetime (similar to 2-4 h). Such dynamic behavior has significant implications for the production and phase partitioning of pONs, organic aerosol mass, and reactive nitrogen speciation in a forested environment.
  • Dingilian, Kayane K.; Halonen, Roope; Tikkanen, Valtteri; Reischl, Bernhard; Vehkamaki, Hanna; Wyslouzil, Barbara E. (2020)
    We studied the homogeneous nucleation of carbon dioxide in the carrier gas argon for concentrations of CO(2)ranging from 2 to 39 mole percent using three experimental methods. Position-resolved pressure trace measurements (PTM) determined that the onset of nucleation occurred at temperatures between 75 and 92 K with corresponding CO(2)partial pressures of 39 to 793 Pa. Small angle X-ray scattering (SAXS) measurements provided particle size distributions and aerosol number densities. Number densities of approximately 10(12)cm(-3), and characteristic times ranging from 6 to 13 mu s, resulted in measured nucleation rates on the order of 5 x 10(17)cm(-3)s(-1), values that are consistent with other nucleation rate measurements in supersonic nozzles. Finally, we used Fourier transform infrared (FTIR) spectroscopy to identify that the condensed CO(2)particles were crystalline cubic solids with either sharp or rounded corners. Molecular dynamics simulations, however, suggest that CO(2)forms liquid-like critical clusters before transitioning to the solid phase. Furthermore, the critical clusters are not in thermal equilibrium with the carrier gas. Comparisons with nucleation theories were therefore made assuming liquid-like critical clusters and incorporating non-isothermal correction factors.
  • Patton, David R.; Wilson, Kieran D.; Metrow, Colin J.; Ellison, Sara L.; Torrey, Paul; Brown, Westley; Hani, Maan H.; McAlpine, Stuart; Moreno, Jorge; Woo, Joanna (2020)
    We use the IllustrisTNG cosmological hydrodynamical simulations to investigate how the specific star formation rates (sSFRs) of massive galaxies (M-* > 10(10) M-circle dot) depend on the distance to their closest companions. We estimate sSFR enhancements by comparing with control samples that are matched in redshift, stellar mass, local density, and isolation, and we restrict our analysis to pairs with stellar mass ratios of 0.1 to 10. At small separations (similar to 15 kpc), the mean sSFR is enhanced by a factor of 2.0 +/- 0.1 in the flagship (110.7Mpc)(3) simulation (TNG100-1). Statistically significant enhancements extend out to 3D separations of 280 kpc in the (302.6Mpc)(3) simulation (TNG300-1). We find similar trends in the EAGLE and Illustris simulations, although their sSFR enhancements are lower than those in TNG100-1 by about a factor of two. Enhancements in IllustrisTNG galaxies are seen throughout the redshift range explored (0
  • Li, Xinpei; Lan, Hangzhen; Hartonen, Kari; Jussila, Matti; Wang, Xinghua; Riekkola, Marja-Liisa (2020)
    Today, wide variety of adsorbents have been developed for sample pretreatment to concentrate and separate harmful substances. However, only a few solid phase microextraction Arrow adsorbents are commercially available. In this study, we developed a new solid phase microextraction Arrow coating, in which nanosheets layered double hydroxides and poly(vinylpyrrolidone) were utilized as the extraction phase and poly(vinyl chloride) as the adhesive. This new coating entailed higher extraction capacity for several volatile organic compounds (allyl methyl sulfide, methyl propyl sulfide, 3-pentanone, 2-butanone, and methyl isobutyl ketone) compared to the commercial Carboxen 1000/polydimethylsiloxane coating. Fabrication parameters for the coating were optimized and extraction and desorption conditions were investigated. The validation of the new solid phase microextraction Arrow coating was accomplished using water sample spiked with volatile organic compounds. Under the optimal conditions, the limits of quantification for the five volatile organic compounds by the new solid phase microextraction Arrow coating and developed gas chromatography with mass spectrometry method were in the range of 0.2-4.6 ng/mL. The proposed method was briefly applied for enrichment of volatile organic compounds in sludge.
  • Deshev, Boris; Haines, Christopher; Hwang, Ho Seong; Finoguenov, Alexis; Taylor, Rhys; Orlitova, Ivana; Einasto, Maret; Ziegler, Bodo (2020)
    Aims. We qualitatively assess and map the relative contribution of pre-processing and cluster related processes to the build-up of A963, a massive cluster at z=0.2 showing an unusually high fraction of star forming galaxies in its interior.Methods. We use Voronoi binning of positions of cluster members on the plane of the sky in order to map the 2D variations of galaxy properties in the centre and infall region of A963. We map four galaxy parameters (fraction of star forming galaxies, specific star formation rate, HI deficiency and age of the stellar population) based on full SED fitting, 21 cm imaging and optical spectroscopy.Results. We find an extended region dominated by passive galaxies along a north-south axis crossing the cluster centre, possibly associated with known filaments of the large-scale structure. There are signs that the passive galaxies in this region were quenched long before their arrival in the vicinity of the cluster. Contrary to that, to the east and west of the cluster centre lie regions of recent accretion dominated by gas rich, actively star forming galaxies not associated with any substructure or filament. The few passive galaxies in this region appear to be recently quenched, and some gas rich galaxies show signs of ongoing ram-pressure stripping. We report the first tentative observations at 21 cm of ongoing ram-pressure stripping at z=0.2, as well as observed inflow of low-entropy gas into the cluster along filaments of the large-scale structure.Conclusions. The observed galaxy content of A963 is a result of strongly anisotropic accretion of galaxies with different properties. Gas rich, star forming galaxies are being accreted from the east and west of the cluster and these galaxies are being quenched at r<R-200, likely by ram-pressure stripping. The bulk of the accretion onto the cluster, containing multiple groups, happens along the north-south axis and brings mostly passive galaxies, likely quenched before entering A963.
  • Roldin, P.; Liao, L.; Mogensen, D.; Dal Maso, M.; Rusanen, A.; Kerminen, V. -M.; Mentel, T. F.; Wildt, J.; Kleist, E.; Kiendler-Scharr, A.; Tillmann, R.; Ehn, M.; Kulmala, Markku; Boy, M. (2015)
    We used the Aerosol Dynamics gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM) to simulate the contribution of BVOC plant emissions to the observed new particle formation during photooxidation experiments performed in the Julich Plant-Atmosphere Chamber and to evaluate how well smog chamber experiments can mimic the atmospheric conditions during new particle formation events. ADCHAM couples the detailed gas-phase chemistry from Master Chemical Mechanism with a novel aerosol dynamics and particle phase chemistry module. Our model simulations reveal that the observed particle growth may have either been controlled by the formation rate of semi- and low-volatility organic compounds in the gas phase or by acid catalysed heterogeneous reactions between semi-volatility organic compounds in the particle surface layer (e.g. peroxyhemiacetal dimer formation). The contribution of extremely low-volatility organic gas-phase compounds to the particle formation and growth was suppressed because of their rapid and irreversible wall losses, which decreased their contribution to the nano-CN formation and growth compared to the atmospheric situation. The best agreement between the modelled and measured total particle number concentration (R-2 > 0.95) was achieved if the nano-CN was formed by kinetic nucleation involving both sulphuric acid and organic compounds formed from OH oxidation of BVOCs.
  • Mohr, Claudia; Thornton, Joel A.; Heitto, Arto; Lopez-Hilfiker, Felipe D.; Lutz, Anna; Riipinen, Ilona; Hong, Juan; Donahue, Neil M.; Hallquist, Mattias; Petaja, Tuukka; Kulmala, Markku; Yli-Juuti, Taina (2019)
    Particles formed in the atmosphere via nucleation provide about half the number of atmospheric cloud condensation nuclei, but in many locations, this process is limited by the growth of the newly formed particles. That growth is often via condensation of organic vapors. Identification of these vapors and their sources is thus fundamental for simulating changes to aerosol-cloud interactions, which are one of the most uncertain aspects of anthropogenic climate forcing. Here we present direct molecular-level observations of a distribution of organic vapors in a forested environment that can explain simultaneously observed atmospheric nanoparticle growth from 3 to 50 nm. Furthermore, the volatility distribution of these vapors is sufficient to explain nanoparticle growth without invoking particle-phase processes. The agreement between observed mass growth, and the growth predicted from the observed mass of condensing vapors in a forested environment thus represents an important step forward in the characterization of atmospheric particle growth.