Temperature-Controlled Dual-Beam Optical Trap for Single Particle Studies of Organic Aerosol

2021 ◽  
Author(s):  
Alexander Logozzo ◽  
Thomas C. Preston
Keyword(s):  
Single Particle ◽  
Optical Trap ◽  
Organic Aerosol ◽  
Dual Beam ◽  
Temperature Controlled

Trapping positions in a dual-beam optical trap

2021 ◽  
Vol 130 (18) ◽  
pp. 183105
Author(s):  
Aidan Rafferty ◽  
Thomas C. Preston
Keyword(s):  
Optical Trap ◽  
Dual Beam

A PZT-assisted single particle loading method for dual-fiber optical trap in air

2020 ◽  
Vol 126 ◽  
pp. 106115
Author(s):  
Guangzong Xiao ◽  
Tengfang Kuang ◽  
Wei Xiong ◽  
Xiang Han ◽  
Hui Luo
Keyword(s):  
Single Particle ◽  
Optical Trap ◽  
Particle Loading ◽  
Loading Method ◽  
Fiber Optical

scholarly journals A new aerosol flow reactor to study secondary organic aerosol

2019 ◽  
Vol 12 (8) ◽  
pp. 4519-4541 ◽  
Author(s):  
Kelly L. Pereira ◽  
Grazia Rovelli ◽  
Young C. Song ◽  
Alfred W. Mayhew ◽  
Jonathan P. Reid ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Chemical Composition ◽  
Relative Humidity ◽  
Single Particle ◽  
Physical State ◽  
Flow Reactor ◽  
Organic Aerosol ◽  
Physiochemical Properties ◽  
Formation Conditions

Abstract. Gas-particle equilibrium partitioning is a fundamental concept used to describe the growth and loss of secondary organic aerosol (SOA). However, recent literature has suggested that gas-particle partitioning may be kinetically limited, preventing volatilization from the aerosol phase as a result of the physical state of the aerosol (e.g. glassy, viscous). Experimental measurements of diffusion constants within viscous aerosol are limited and do not represent the complex chemical composition observed in SOA (i.e. multicomponent mixtures). Motivated by the need to address fundamental questions regarding the effect of the physical state and chemical composition of a particle on gas-particle partitioning, we present the design and operation of a newly built 0.3 m3 continuous-flow reactor (CFR), which can be used as a tool to gain considerable insights into the composition and physical state of SOA. The CFR was used to generate SOA from the photo-oxidation of α-pinene, limonene, β-caryophyllene and toluene under different experimental conditions (i.e. relative humidity, VOC and VOC∕NOx ratios). Up to 102 mg of SOA mass was collected per experiment, allowing the use of highly accurate compositional- and single-particle analysis techniques, which are not usually accessible due to the large quantity of organic aerosol mass required for analysis. A suite of offline analytical techniques was used to determine the chemical composition and physical state of the generated SOA, including attenuated total reflectance infrared spectroscopy; carbon, hydrogen, nitrogen, and sulfur (CHNS) elemental analysis; 1H and 1H-13C nuclear magnetic resonance spectroscopy (NMR); ultra-performance liquid chromatography ultra-high-resolution mass spectrometry (UHRMS); high-performance liquid chromatography ion-trap mass spectrometry (HPLC-ITMS); and an electrodynamic balance (EDB). The oxygen-to-carbon (O∕C) and hydrogen-to-carbon (H∕C) ratios of generated SOA samples (determined using a CHNS elemental analyser) displayed good agreement with literature values and were consistent with the characteristic Van Krevelen diagram trajectory, with an observed slope of −0.41. The elemental composition of two SOA samples formed in separate replicate experiments displayed excellent reproducibility, with the O∕C and H∕C ratios of the SOA samples observed to be within error of the analytical instrumentation (instrument accuracy ±0.15 % to a reference standard). The ability to use a highly accurate CHNS elemental analyser to determine the elemental composition of the SOA samples allowed us to evaluate the accuracy of reported SOA elemental compositions using UHRMS (a commonly used technique). In all of the experiments investigated, the SOA O∕C ratios obtained for each SOA sample using UHRMS were lower than the O∕C ratios obtained from the CHNS analyser (the more accurate and non-selective technique). The average difference in the ΔO∕C ratios ranged from 19 % to 45 % depending on the SOA precursor and formation conditions. α-pinene SOA standards were generated from the collected SOA mass using semi-preparative HPLC-ITMS coupled to an automated fraction collector, followed by 1H NMR spectroscopy. Up to 35.8±1.6 % (propagated error of the uncertainty in the slope of the calibrations graphs) of α-pinene SOA was quantified using this method; a considerable improvement from most previous studies. Single aerosol droplets were generated from the collected SOA samples and trapped within an EDB at different temperatures and relative humidities to investigate the dynamic changes in their physiochemical properties. The volatilization of organic components from toluene and β-caryophyllene SOA particles at 0 % relative humidity was found to be kinetically limited, owing to particle viscosity. The unconventional use of a newly built CFR, combined with comprehensive offline chemical characterization and single-particle measurements, offers a unique approach to further our understanding of the relationship between SOA formation conditions, chemical composition and physiochemical properties.

scholarly journals Viscoelastic deformation of lipid bilayer vesicles

Soft Matter ◽  
2015 ◽  
Vol 11 (37) ◽  
pp. 7385-7391 ◽  
Author(s):  
Shao-Hua Wu ◽  
Shalene Sankhagowit ◽  
Roshni Biswas ◽  
Shuyang Wu ◽  
Michelle L. Povinelli ◽  
...  
Keyword(s):  
Lipid Bilayer ◽  
Optical Trap ◽  
Strain Response ◽  
Viscoelastic Deformation ◽  
Stress Strain ◽  
Dual Beam ◽  
Lipid Bilayer Vesicles ◽  
Lipid Bilayer Vesicle ◽  
Bilayer Vesicle

A dual-beam optical trap (DBOT, left) is used to characterize a viscoelastic stress–strain response in a lipid bilayer vesicle (right).

scholarly journals The lensing effect of trapped particles in a dual-beam optical trap

2015 ◽  
Vol 23 (4) ◽  
pp. 5221 ◽  
Author(s):  
Steffen Grosser ◽  
Anatol W. Fritsch ◽  
Tobias R. Kießling ◽  
Roland Stange ◽  
Josef A. Käs
Keyword(s):  
Optical Trap ◽  
Trapped Particles ◽  
Dual Beam ◽  
Lensing Effect

Organic Aerosol Mixing Observed by Single-Particle Mass Spectrometry

2013 ◽  
Vol 117 (51) ◽  
pp. 13935-13945 ◽  
Author(s):  
Ellis Shipley Robinson ◽  
Rawad Saleh ◽  
Neil M. Donahue
Keyword(s):  
Mass Spectrometry ◽  
Single Particle ◽  
Organic Aerosol ◽  
Particle Mass ◽  
Single Particle Mass Spectrometry

scholarly journals Collection efficiency of α-pinene secondary organic aerosol particles explored via light scattering single particle aerosol mass spectrometry

2016 ◽  
Author(s):  
Ellis Shipley Robinson ◽  
Timothy B. Onasch ◽  
Douglas Worsnop ◽  
Neil M. Donahue
Keyword(s):  
Light Scattering ◽  
Single Particle ◽  
Secondary Organic Aerosol ◽  
Collection Efficiency ◽  
Organic Aerosol ◽  
Ionization Efficiency ◽  
Aerosol Mass ◽  
The Mean ◽  
Hot Surface ◽  
Effective Ionization

Abstract. We investigated the collection efficiency and effective ionization efficiency for secondary organic aerosol (SOA) particles made from α-pinene + O3 using the single-particle capabilities of the Aerosol Mass Spectrometer (AMS). The mean count-based collection efficiency (CEp) for SOA across these experiments is 0.30 (±0.04 S.D.), ranging from 0.25 to 0.40. The mean mass-based collection efficiency (CEm) is 0.49 (±0.07 S.D.). This sub-unit collection efficiency and delayed vaporization is attributable to particle bounce in the vaporization region. Using the coupled optical and chemical detection of the light scattering single-particle (LSSP) module 5 of the AMS, we provide clear evidence that ''delayed vaporization'' is somewhat of a misnomer for these particles: SOA particles that appear within the chopper window do not vaporize at a slow rate; rather, they flash-vaporize, but often not on the initial impact with the vaporizer, and instead upon a subsequent impact with a hot surface in the vaporization region. We also find that the effective ionization efficiency (defined as ions per particle, IPP) decreases with delayed arrival time. CEp is not a function of particle size (for the mobility diameter range investigated, 170–460 nm), but we did see a decrease in CEp with thermodenuder temperature, implying that oxidation state and/or volatility can affect CEp for SOA.

scholarly journals Single particle characterization of biomass burning organic aerosol (BBOA): evidence for non-uniform mixing of high molecular weight organics and potassium

2015 ◽  
Vol 15 (22) ◽  
pp. 32157-32183 ◽  
Author(s):  
A. K. Y. Lee ◽  
M. D. Willis ◽  
R. M. Healy ◽  
J. M. Wang ◽  
C.-H. Jeong ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Black Carbon ◽  
High Molecular Weight ◽  
Biomass Burning ◽  
Single Particle ◽  
Critical Role ◽  
Organic Aerosol ◽  
Mixing State ◽  
Particle Measurements ◽  
Near Ultraviolet

Abstract. Biomass burning is a major source of black carbon (BC) and primary organic aerosol globally. In particular, biomass burning organic aerosol (BBOA) is strongly associated with atmospheric brown carbon (BrC) that absorbs near ultraviolet and visible light, resulting in significant impacts on regional visibility degradation and radiative forcing. The mixing state of BBOA can play a critical role in the prediction of aerosol optical properties. In this work, single particle measurements from a soot-particle aerosol mass spectrometer coupled with a light scattering module (LS-SP-AMS) were performed to examine the mixing state of BBOA, refractory black carbon (rBC) and potassium (K+, a tracer for biomass burning aerosol) in an air mass influenced by aged biomass burning. Cluster analysis of single particle measurements identified five BBOA-related particle types. rBC accounted for 3–14 w.t. % of these particle types on average. Only one particle type exhibited a strong ion signal for K+, with mass spectra characterized by low molecular weight organic species. The remaining four particle types were classified based on the apparent molecular weight of the BBOA constituents. Two particle types were associated with low potassium content and significant amounts of high molecular weight (HMW) organic compounds. Our observations indicate non-uniform mixing of particles within a biomass burning plume in terms of molecular weight and illustrate that HMW BBOA can be a key contributor to low-volatility BrC observed in BBOA particles.

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