Dimers in nucleating vapors

Lushnikov, A. A.; Kulmala, Markku

doi:10.1103/physreve.58.3157

Cited by 43 publications

(25 citation statements)

References 13 publications

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“…The proposed activation processes involve sulphuric acid either as the activating vapour or as a constituent of the activated clusters. This theory is supported by the recent study by Sihto et al (2006), which reports the cluster activation as a potential formation mechanism, along with kinetic nucleation (McMurry and Friedlander, 1979;Lushnikov and Kulmala, 1998). Spracklen et al (2006) have implemented the cluster activation scheme as the particle formation mechanism in a global aerosol microphysics model.…”

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confidence: 69%

Connections between atmospheric sulphuric acid and new particle formation during QUEST III–IV campaigns in Heidelberg and Hyytiälä

et al. 2007

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Abstract. This study investigates the connections between atmospheric sulphuric acid and new particle formation during QUEST III and BACCI/QUEST IV campaigns. The campaigns have been conducted in Heidelberg (2004) and Hyytiälä (2005), the first representing a polluted site surrounded by deciduous forest, and the second a rural site in a boreal forest environment. We have studied the role of sulphuric acid in particle formation and growth by determining 1) the power-law dependencies between sulphuric acid ([H 2 SO 4 ]), and particle concentrations (N 3−6 ) or formation rates at 1 nm and 3 nm (J 1 and J 3 ); 2) the time delays between [H 2 SO 4 ] and N 3−6 or J 3 , and the growth rates for 1-3 nm particles; 3) the empirical nucleation coefficients A and K in relations J 1 =A[H 2 SO 4 ] and J 1 =K[H 2 SO 4 ] 2 , respectively; 4) theoretical predictions for J 1 and J 3 for the days when no significant particle formation is observed, based on the observed sulphuric acid concentrations and condensation sinks. In both environments, N 3−6 or J 3 and [H 2 SO 4 ] were linked via a power-law relation with exponents typically ranging from 1 to 2. The result suggests that the cluster activation theory and kinetic nucleation have the potential to explain the observed particle formation. However, some differences between the sites existed: The nucleation coefficients were about an order of magnitude greater in Heidelberg than in Hyytiälä conditions. The time lags between J 3 and [H 2 SO 4 ] were consistently lower than the corresponding Correspondence to: I. Riipinen (ilona.riipinen@helsinki.fi) delays between N 3−6 and [H 2 SO 4 ]. The exponents in the J 3 ∝[H 2 SO 4 ] n J 3 -connection were consistently higher than or equal to the exponents in the relation N 3−6 ∝[H 2 SO 4 ] n N36 . In the J 1 values, no significant differences were found between the observed rates on particle formation event days and the predictions on non-event days. The J 3 values predicted by the cluster activation or kinetic nucleation hypotheses, on the other hand, were considerably lower on non-event days than the rates observed on particle formation event days. This study provides clear evidence implying that the main process limiting the observable particle formation is the competition between the growth of the freshly formed particles and their loss by scavenging, rather than the initial particle production by nucleation of sulphuric acid. In general, it can be concluded that the simple models based on sulphuric acid concentrations and particle formation by cluster activation or kinetic nucleation can predict the occurence of atmospheric particle formation and growth well, if the particle scavenging is accurately accounted for.

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confidence: 69%

Connections between atmospheric sulphuric acid and new particle formation during QUEST III–IV campaigns in Heidelberg and Hyytiälä

et al. 2007

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“…It is important to focus on the fundamental point is that a cluster will participate in birth and death-style population dynamics if its decay probability is Markovian. This is equivalent in spirit to the frequently discussed criterion that the cluster should be long-lived [16,17]. This means that the typical lifetime, or inverse mean decay rate, is longer than typical timescales in the molecular dynamics: the decay rate is then presumed to be free of memory effects.…”

Section: Introductionmentioning

confidence: 90%

A dynamical definition of quasibound molecular clusters

Harris

Ford

2003

The Journal of Chemical Physics

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Molecular configurations which count as snapshots of a quasi-bound cluster are identified through a retrospective dynamical definition. The trajectory of a molecular cluster is followed, and a clear evaporation event is considered to have occurred when a molecule moves a very long distance away from the others. The cluster is judged to have broken before this condition is satisfied, however, at the instant that the energy of the departing molecule in the centre of mass frame becomes positive. The decay of a cluster is therefore defined dynamically as the production of a molecule with positive energy on a separating trajectory. Not all positive energy molecules created by the system follow such a trajectory, hence the need to examine the subsequent behaviour in molecular dynamics. We simulate a sequence of decays by repairing broken clusters as they occur. This approach enables us to calculate mean decay rates of isolated Lennard-Jones clusters in what promises to be a physically realistic fashion.

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“…The kinetic theory (McMurry and Friedlander, 1979;Lushnikov and Kulmala, 1998) suggests that critical clusters are formed by collisions of two sulfuric acid molecules. According to kinetic gas theory, the collision frequency of two molecules is correlated with the concentration of both molecules.…”

Section: Determination Of the Nucleation Coefficientsmentioning

confidence: 99%

Evaluation on the role of sulfuric acid in the mechanisms of new particle formation for Beijing case

Wang

Yue

et al. 2011

Atmos. Chem. Phys.

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Abstract. New particle formation (NPF) is considered as an important mechanism for gas-to-particle transformation, and gaseous sulfuric acid is believed as a crucial precursor. Up to now few field-based studies on nucleation mechanisms and the role of sulfuric acid were conducted in China. In this study, simultaneously measurements of particle number size distributions and gaseous sulfuric acid concentrations were performed from July to September in 2008. Totally, 22 new particle formation events were observed during the entire 85 campaign days. The results show that in the case of both higher source and sink values, the result of the competition between source and sink is more likely the key limiting factor to determine the observation of NPF events in Beijing. The concentrations of gaseous sulfuric acid show good correlations with freshly nucleated particles (N 3−6 ) and formation rates (J 3 and J 1.5 ). The power-law relationship between H 2 SO 4 concentration and N 3−6 or J is adopted to explore the nucleation mechanism. The exponents are showed a great range (from 1 to 7). More than half of the NPF events exhibit an exponent larger than 2.5. For these cases, the thermodynamic process works better than the activation or kinetic nucleation theories to explain the nucleation events in urban atmosphere of Beijing.

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Dimers in nucleating vapors

Cited by 43 publications

References 13 publications

Connections between atmospheric sulphuric acid and new particle formation during QUEST III–IV campaigns in Heidelberg and Hyytiälä

Connections between atmospheric sulphuric acid and new particle formation during QUEST III–IV campaigns in Heidelberg and Hyytiälä

A dynamical definition of quasibound molecular clusters

Evaluation on the role of sulfuric acid in the mechanisms of new particle formation for Beijing case

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