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About: Vapours is a(n) research topic. Over the lifetime, 1153 publication(s) have been published within this topic receiving 15022 citation(s).

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Journal ArticleDOI
Abstract: The dependence of the coefficient of diffusion, D, upon the porosity, S, of a granular solid is investigated experimentally. For steady state conditions, using carbon disulphide and acetone vapours, it is shown that a curve connecting D/D0 and S can be drawn which is independent of the nature of the solid, its moisture content and, within limits, its texture. For a limited range of values of S (0·0 < S < 0·7) a good approximation is D/D0 = 0·66S and over this range the diffusion coefficients are larger than those found by Buckingham for carbon dioxide.Investigation of the non-steady state shows that in soils the attainment of pressure equilibrium is retarded by adsorption, and it is suggested that Buckingham's low values for steady-state conditions can be attributed to premature observations of the diffusion rates; the steady state had probably not been attained when his measurements were made.

453 citations

Journal ArticleDOI
04 Apr 2002-Nature
TL;DR: It is shown, to the knowledge for the first time, that these newly formed particles are composed primarily of organic species, such as cis-pinonic acid and pinic acid, produced by oxidation of terpenes in organic vapours released from the canopy.
Abstract: Aerosol particles produced over forested areas may affect climate by acting as nuclei for cloud condensation, but their composition (and hence the chemical species that drive their production) remains an open question. Here we show, to our knowledge for the first time, that these newly formed particles (3–5 nm in diameter) are composed primarily of organic species, such as cis-pinonic acid and pinic acid, produced by oxidation of terpenes in organic vapours released from the canopy1,2,3,4.

411 citations

Journal ArticleDOI
Jasmin Tröstl1, Wayne Chuang2, Hamish Gordon3, Martin Heinritzi4, Chao Yan5, Ugo Molteni1, Lars Ahlm6, Carla Frege1, F. Bianchi5, F. Bianchi7, F. Bianchi1, Robert Wagner5, Mario Simon4, Katrianne Lehtipalo1, Katrianne Lehtipalo5, Christina Williamson8, Christina Williamson9, Christina Williamson4, J. S. Craven10, Jonathan Duplissy5, Jonathan Duplissy11, Alexey Adamov5, Joao Almeida3, Anne-Kathrin Bernhammer12, Martin Breitenlechner12, Sophia Brilke4, Antonio Dias3, Sebastian Ehrhart3, Richard C. Flagan10, Alessandro Franchin5, Claudia Fuchs1, Roberto Guida3, Martin Gysel1, Armin Hansel12, Christopher R. Hoyle1, Tuija Jokinen5, Heikki Junninen5, Juha Kangasluoma5, Helmi Keskinen9, Helmi Keskinen5, Helmi Keskinen13, Jaeseok Kim13, Jaeseok Kim9, Manuel Krapf1, Andreas Kürten4, Ari Laaksonen13, Ari Laaksonen14, Michael J. Lawler15, Michael J. Lawler13, Markus Leiminger4, Serge Mathot3, Ottmar Möhler16, Tuomo Nieminen11, Tuomo Nieminen5, Antti Onnela3, Tuukka Petäjä5, Felix Piel4, Pasi Miettinen13, Matti P. Rissanen5, Linda Rondo4, Nina Sarnela5, Siegfried Schobesberger5, Siegfried Schobesberger9, Kamalika Sengupta17, Mikko Sipilä5, James N. Smith13, James N. Smith18, Gerhard Steiner5, Gerhard Steiner19, Gerhard Steiner12, António Tomé20, Annele Virtanen13, Andrea Christine Wagner4, Ernest Weingartner9, Ernest Weingartner1, Daniela Wimmer4, Daniela Wimmer5, Paul M. Winkler19, Penglin Ye2, Kenneth S. Carslaw17, Joachim Curtius4, Josef Dommen1, Jasper Kirkby3, Jasper Kirkby4, Markku Kulmala5, Ilona Riipinen6, Douglas R. Worsnop11, Douglas R. Worsnop5, Neil M. Donahue2, Neil M. Donahue5, Urs Baltensperger1 
26 May 2016-Nature
TL;DR: It is shown that organic vapours alone can drive nucleation, and a particle growth model is presented that quantitatively reproduces the measurements and implements a parameterization of the first steps of growth in a global aerosol model that can change substantially in response to concentrations of atmospheric cloud concentration nuclei.
Abstract: About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer. Although recent studies predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon, and the presence of a possible Kelvin (curvature) effect, which inhibits organic vapour condensation on the smallest particles (the nano-Kohler theory), has so far remained ambiguous. Here we present experiments performed in a large chamber under atmospheric conditions that investigate the role of organic vapours in the initial growth of nucleated organic particles in the absence of inorganic acids and bases such as sulfuric acid or ammonia and amines, respectively. Using data from the same set of experiments, it has been shown that organic vapours alone can drive nucleation. We focus on the growth of nucleated particles and find that the organic vapours that drive initial growth have extremely low volatilities (saturation concentration less than 10(-4.5) micrograms per cubic metre). As the particles increase in size and the Kelvin barrier falls, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility (saturation concentrations of 10(-4.5) to 10(-0.5) micrograms per cubic metre). We present a particle growth model that quantitatively reproduces our measurements. Furthermore, we implement a parameterization of the first steps of growth in a global aerosol model and find that concentrations of atmospheric cloud concentration nuclei can change substantially in response, that is, by up to 50 per cent in comparison with previously assumed growth rate parameterizations.

387 citations

Journal ArticleDOI
Abstract: In situ catalytic upgrading of biomass derived fast pyrolysis vapours in a fixed bed reactor using mesoporous materials

247 citations

Journal ArticleDOI
Abstract: . Sulphuric acid and organic vapours have been identified as the key components in the ubiquitous secondary new particle formation in the atmosphere. In order to assess their relative contribution and spatial variability, we analysed altogether 36 new particle formation events observed at four European measurement sites during EUCAARI campaigns in 2007–2009. We tested models of several different nucleation mechanisms coupling the formation rate of neutral particles (J) with the concentration of sulphuric acid ([H2SO4]) or low-volatility organic vapours ([org]) condensing on sub-4 nm particles, or with a combination of both concentrations. Furthermore, we determined the related nucleation coefficients connecting the neutral nucleation rate J with the vapour concentrations in each mechanism. The main goal of the study was to identify the mechanism of new particle formation and subsequent growth that minimizes the difference between the modelled and measured nucleation rates. At three out of four measurement sites – Hyytiala (Finland), Melpitz (Germany) and San Pietro Capofiume (Italy) – the nucleation rate was closely connected to squared sulphuric acid concentration, whereas in Hohenpeissenberg (Germany) the low-volatility organic vapours were observed to be dominant. However, the nucleation rate at the sulphuric acid dominant sites could not be described with sulphuric acid concentration and a single value of the nucleation coefficient, as K in J=K [H2SO4]2, but the median coefficients for different sites varied over an order of magnitude. This inter-site variation was substantially smaller when the heteromolecular homogenous nucleation between H2SO4 and organic vapours was assumed to take place in addition to homogenous nucleation of H2SO4 alone, i.e., J=KSA1[H2SO4]2+KSA2[H2SO4][org]. By adding in this equation a term describing homomolecular organic vapour nucleation, Ks3[org]2, equally good results were achieved. In general, our results suggest that organic vapours do play a role, not only in the condensational growth of the particles, but also in the nucleation process, with a site-specific degree.

228 citations

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