Critical cluster size and droplet nucleation rate from growth and decay simulations of Lennard-Jones clusters

2000 ◽  
Vol 112 (9) ◽  
pp. 4193-4202 ◽  
Author(s):  
Hanna Vehkamäki ◽  
Ian J. Ford
Keyword(s):  
Nucleation Rate ◽  
Cluster Size ◽  
Critical Cluster ◽  
Lennard Jones ◽  
Droplet Nucleation ◽  
Critical Cluster Size

scholarly journals Performance of diethylene glycol-based particle counters in the sub-3 nm size range

2013 ◽  
Vol 6 (7) ◽  
pp. 1793-1804 ◽  
Author(s):  
D. Wimmer ◽  
K. Lehtipalo ◽  
A. Franchin ◽  
J. Kangasluoma ◽  
F. Kreissl ◽  
...  
Keyword(s):  
High Resolution ◽  
Laminar Flow ◽  
Nucleation Rate ◽  
Diethylene Glycol ◽  
Cluster Size ◽  
Detection Efficiency ◽  
Working Fluid ◽  
Critical Cluster ◽  
Mixing Ratios ◽  
Critical Cluster Size

Abstract. When studying new particle formation, the uncertainty in determining the "true" nucleation rate is considerably reduced when using condensation particle counters (CPCs) capable of measuring concentrations of aerosol particles at sizes close to or even at the critical cluster size (1–2 nm). Recently, CPCs able to reliably detect particles below 2 nm in size and even close to 1 nm became available. Using these instruments, the corrections needed for calculating nucleation rates are substantially reduced compared to scaling the observed formation rate to the nucleation rate at the critical cluster size. However, this improved instrumentation requires a careful characterization of their cut-off size and the shape of the detection efficiency curve because relatively small shifts in the cut-off size can translate into larger relative errors when measuring particles close to the cut-off size. Here we describe the development of two continuous-flow CPCs using diethylene glycol (DEG) as the working fluid. The design is based on two TSI 3776 counters. Several sets of measurements to characterize their performance at different temperature settings were carried out. Furthermore, two mixing-type particle size magnifiers (PSM) A09 from Airmodus were characterized in parallel. One PSM was operated at the highest mixing ratio (1 L min−1 saturator flow), and the other was operated in a scanning mode, where the mixing ratios are changed periodically, resulting in a range of cut-off sizes. The mixing ratios are determined by varying the saturator flow, where the aerosol flow stays constant at 2.5 L min−1. Different test aerosols were generated using a nano-differential mobility analyser (nano-DMA) or a high-resolution DMA, to obtain detection efficiency curves for all four CPCs. One calibration setup included a high-resolution mass spectrometer (APi-TOF) for the determination of the chemical composition of the generated clusters. The lowest cut-off sizes were achieved with negatively charged ammonium sulfate clusters, resulting in cut-offs of 1.4 nm for the laminar flow CPCs and 1.2 and 1.1 nm for the PSMs. A comparison of one of the laminar-flow CPCs and one of the PSMs measuring ambient and laboratory air showed good agreement between the instruments.

scholarly journals Performance of diethylene glycol based particle counters in the sub 3 nm size range

2013 ◽  
Vol 6 (1) ◽  
pp. 2151-2181 ◽  
Author(s):  
D. Wimmer ◽  
K. Lehtipalo ◽  
A. Franchin ◽  
J. Kangasluoma ◽  
F. Kreissl ◽  
...  
Keyword(s):  
High Resolution ◽  
Laminar Flow ◽  
Nucleation Rate ◽  
Diethylene Glycol ◽  
Cluster Size ◽  
Detection Efficiency ◽  
Formation Rate ◽  
Working Fluid ◽  
Critical Cluster ◽  
Critical Cluster Size

Abstract. When studying new particle formation, the uncertainty in determining the "true" nucleation rate is considerably reduced when using Condensation Particle Counters (CPCs) capable of measuring concentrations of aerosol particles at sizes close to or even at the critical cluster size (1–2 nm). Recently CPCs, able to reliably detect particles below 2 nm in size and even close to 1 nm became available. The corrections needed to calculate nucleation rates are substantially reduced compared to scaling the observed formation rate to the nucleation rate at the critical cluster size. However, this improved instrumentation requires a careful characterization of their cut-off size and the shape of the detection efficiency curve because relatively small shifts in the cut-off size can translate into larger relative errors when measuring particles close to the cut-off size. Here we describe the development of two continuous flow CPCs using diethylene glycol (DEG) as the working fluid. The design is based on two TSI 3776 counters. Several sets of measurements to characterize their performance at different temperature settings were carried out. Furthermore two mixing-type Particle Size Magnifiers (PSM) A09 from Airmodus were characterized in parallel. One PSM was operated at the highest mixing ratio (1 L min−1 saturator flow), and the other was operated in a scanning mode, where the mixing ratios are changed periodically, resulting in a range of cut-off sizes. Different test aerosols were generated using a nano-Differential Mobility Analyzer (nano-DMA) or a high resolution DMA, to obtain detection efficiency curves for all four CPCs. One calibration setup included a high resolution mass spectrometer (APi-TOF) for the determination of the chemical composition of the generated clusters. The lowest cut-off sizes were achieved with negatively charged ammonium sulphate clusters, resulting in cut-offs of 1.4 nm for the laminar flow CPCs and 1.2 and 1.1 nm for the PSMs. A comparison of one of the laminar-flow CPCs and one of the PSMs measuring ambient and laboratory air showed good agreement between the instruments.

scholarly journals Nucleation of Ga droplets self-assembly on GaAs(111)A substrates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Artur Tuktamyshev ◽  
Alexey Fedorov ◽  
Sergio Bietti ◽  
Stefano Vichi ◽  
Riccardo Tambone ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Size Distribution ◽  
Self Assembly ◽  
Cluster Size ◽  
Droplet Size Distribution ◽  
Local Environment ◽  
The Self ◽  
Critical Cluster ◽  
Droplet Nucleation ◽  
High Degree

AbstractWe investigated the nucleation of Ga droplets on singular GaAs(111)A substrates in the view of their use as the seeds for the self-assembled droplet epitaxial quantum dots. A small critical cluster size of 1–2 atoms characterizes the droplet nucleation. Low values of the Hopkins-Skellam index (as low as 0.35) demonstrate a high degree of a spatial order of the droplet ensemble. Around $$350\,^{\circ }\hbox {C}$$ 350 ∘ C the droplet size distribution becomes bimodal. We attribute this observation to the interplay between the local environment and the limitation to the adatom surface diffusion introduced by the Ehrlich–Schwöbel barrier at the terrace edges.

A study of the critical cluster size for water monolayer clusters on a model AgI basal substratea)

1983 ◽  
Vol 78 (1) ◽  
pp. 420-423 ◽  
Author(s):  
Richard C. Ward ◽  
Barbara N. Hale ◽  
Sergio Terrazas
Keyword(s):  
Cluster Size ◽  
Critical Cluster ◽  
Critical Cluster Size

Critical cluster size cannot in practice be determined by slope analysis in atmospherically relevant applications

2014 ◽  
Vol 77 ◽  
pp. 127-144 ◽  
Author(s):  
Oona Kupiainen-Määttä ◽  
Tinja Olenius ◽  
Hannele Korhonen ◽  
Jussi Malila ◽  
Miikka Dal Maso ◽  
...  
Keyword(s):  
Cluster Size ◽  
Critical Cluster ◽  
Slope Analysis ◽  
Critical Cluster Size ◽  
Atmospherically Relevant

Amorphous to Polycrystal Transition Assisted by Ion Beam Irradiation in Silicon

1989 ◽  
Vol 157 ◽  
Author(s):  
C. Spinella ◽  
S. Lombardo ◽  
S. U. Campisano
Keyword(s):  
Cluster Size ◽  
Thermal Process ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Chemical Vapor ◽  
Irradiation Temperature ◽  
Ion Beam Irradiation ◽  
Critical Cluster ◽  
Chemical Vapor Deposited ◽  
Critical Cluster Size

ABSTRACTThe ion beam induced growth of isolated silicon grains has been studied in chemical vapor deposited amorphous layers. The crystal radius increases linearly with the 1on dose and the growth rate depends in a complex way on the irradiation temperature in the 320 - 480 °C investigated temperature range. The grain density does not depend on the ion dose but it increases exponentially with increasing irradiation temperature. The grain density obtained after a pure thermal process on similar samples is In any case larger than the density appearing after ion irradiation. These facts may be explained by assuming that during ion irradiation only pre-existing seeds whose size is larger than a critical value can grow. This critical cluster size is larger than the critical cluster size for a pure thermal process.

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