scholarly journals Elastic back-scattering patterns via particle surface roughness and orientation from single trapped airborne aerosol particles

2017 ◽  
Vol 187 ◽  
pp. 224-231 ◽  
Author(s):  
Richard Fu ◽  
Chuji Wang ◽  
Olga Muñoz ◽  
Gorden Videen ◽  
Joshua L. Santarpia ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Aerosol Particles ◽  
Particle Surface ◽  
Back Scattering

Effects of Particle Surface Roughness on In-Die Flow and Tableting Behavior of Lactose

2019 ◽  
Vol 108 (9) ◽  
pp. 3011-3019 ◽  
Author(s):  
Justin Yong Soon Tay ◽  
Berlinda Wen Ting Kok ◽  
Celine Valeria Liew ◽  
Paul Wan Sia Heng
Keyword(s):  
Surface Roughness ◽  
Particle Surface

Nondestructive Characterization of GaN Films Grown at Low and High Temperatures

1999 ◽  
Vol 591 ◽  
Author(s):  
C.H. Yana ◽  
H.W. Yao ◽  
J.M. Van Hove ◽  
A.M. Wowchak ◽  
P.P. Chow ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Temperatures ◽  
Sapphire Substrates ◽  
Wurtzite Crystal Structure ◽  
Phonon Spectra ◽  
Scattering Geometry ◽  
Back Scattering ◽  
Nondestructive Characterization

ABSTRACTGaN films grown on GaAs and sapphire substrates by molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE) at both low and high temperatures (LT and HT) were characterized by Raman scattering and variable angle spectroscopic ellipsometry (VASE). Optical phonon spectra of GaN films are obtained through back-scattering geometry. Crystal quality of these films was qualitatively examined using phonon line-width. Phonon spectra showed that the HT GaN has wurtzite crystal structure, while LT GaN and GaN/GaAs have cubic-like structures. Thickness nonuniformity and defect-related absorption can be characterized by pseudo dielectric functions directly. Surface roughness also can be determined by using an effective-medium approximation (EMA) over-layer in a VASE analysis. Anisotropic optical constants of GaN, both ordinary and extraordinary, were obtained in the spectral range of 0.75 to 6.5 eV with the consideration of surface roughness, through the small and large angles of incidence, respectively. The film thickness of the GaN was accurately determined via the analysis as well.

scholarly journals Measurement of back-scattering patterns from single laser trapped aerosol particles in air

2016 ◽  
Vol 56 (3) ◽  
pp. B1 ◽  
Author(s):  
Yong-Le Pan ◽  
Chuji Wang ◽  
Leonid A. Beresnev ◽  
Alex J. Yuffa ◽  
Gorden Videen ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Single Laser ◽  
Back Scattering

scholarly journals A method for the direct measurement of surface tension of collected atmospherically relevant aerosol particles using atomic force microscopy

2016 ◽  
Vol 16 (15) ◽  
pp. 9761-9769 ◽  
Author(s):  
Andrew D. Hritz ◽  
Timothy M. Raymond ◽  
Dabrina D. Dutcher
Keyword(s):  
Surface Tension ◽  
Atomic Force Microscopy ◽  
Atmospheric Aerosol ◽  
Aerosol Particles ◽  
Particle Surface ◽  
Ex Situ ◽  
Force Microscopy ◽  
Atomic Force ◽  
Direct Measurements ◽  
Dry Conditions

Abstract. Accurate estimates of particle surface tension are required for models concerning atmospheric aerosol nucleation and activation. However, it is difficult to collect the volumes of atmospheric aerosol required by typical instruments that measure surface tension, such as goniometers or Wilhelmy plates. In this work, a method that measures, ex situ, the surface tension of collected liquid nanoparticles using atomic force microscopy is presented. A film of particles is collected via impaction and is probed using nanoneedle tips with the atomic force microscope. This micro-Wilhelmy method allows for direct measurements of the surface tension of small amounts of sample. This method was verified using liquids, whose surface tensions were known. Particles of ozone oxidized α-pinene, a well-characterized system, were then produced, collected, and analyzed using this method to demonstrate its applicability for liquid aerosol samples. It was determined that oxidized α-pinene particles formed in dry conditions have a surface tension similar to that of pure α-pinene, and oxidized α-pinene particles formed in more humid conditions have a surface tension that is significantly higher.

scholarly journals Spherical tarball particles form through rapid chemical and physical changes of organic matter in biomass-burning smoke

2019 ◽  
Vol 116 (39) ◽  
pp. 19336-19341 ◽  
Author(s):  
Kouji Adachi ◽  
Arthur J. Sedlacek ◽  
Lawrence Kleinman ◽  
Stephen R. Springston ◽  
Jian Wang ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Radiative Forcing ◽  
Global Climate ◽  
Aerosol Particles ◽  
Particle Surface ◽  
Spherical Particles ◽  
Transmission Electron Microscopy Analysis ◽  
Chemical Changes ◽  
Physical Processing ◽  
Organic Particles

Biomass burning (BB) emits enormous amounts of aerosol particles and gases into the atmosphere and thereby significantly influences regional air quality and global climate. A dominant particle type from BB is spherical organic aerosol particles commonly referred to as tarballs. Currently, tarballs can only be identified, using microscopy, from their uniquely spherical shapes following impaction onto a grid. Despite their abundance and potential significance for climate, many unanswered questions related to their formation, emission inventory, removal processes, and optical properties still remain. Here, we report analysis that supports tarball formation in which primary organic particles undergo chemical and physical processing within ∼3 h of emission. Transmission electron microscopy analysis reveals that the number fractions of tarballs and the ratios of N and O relative to K, the latter a conserved tracer, increase with particle age and that the more-spherical particles on the substrates had higher ratios of N and O relative to K. Scanning transmission X-ray spectrometry and electron energy loss spectrometry analyses show that these chemical changes are accompanied by the formation of organic compounds that contain nitrogen and carboxylic acid. The results imply that the chemical changes increase the particle sphericity on the substrates, which correlates with particle surface tension and viscosity, and contribute to tarball formation during aging in BB smoke. These findings will enable models to better partition tarball contributions to BB radiative forcing and, in so doing, better help constrain radiative forcing models of BB events.

scholarly journals A Novel Multi-Scale Particle Morphology Descriptor with the Application of SPHERICAL Harmonics

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3286
Author(s):  
Wei Xiong ◽  
Jianfeng Wang ◽  
Zhuang Cheng
Keyword(s):  
Surface Roughness ◽  
Scale Effect ◽  
Scale Effects ◽  
Particle Surface ◽  
Relative Length ◽  
Particle Morphology ◽  
Length Scale ◽  
Multi Scale ◽  
Rate Of Increase ◽  
Macro Scale

Particle morphology is of great significance to the grain- and macro-scale behaviors of granular soils. Most existing traditional morphology descriptors have three perennial limitations, i.e., dissensus of definition, inter-scale effect, and surface roughness heterogeneity, which limit the accurate representation of particle morphology. The inter-scale effect refers to the inaccurate representation of the morphological features at the target relative length scale (RLS, i.e., length scale with respective to particle size) caused by the inclusion of additional morphological details existing at other RLS. To effectively eliminate the inter-scale effect and reflect surface roughness heterogeneity, a novel spherical harmonic-based multi-scale morphology descriptor Rinc is proposed to depict the incremental morphology variation (IMV) at different RLS. The following conclusions were drawn: (1) the IMV at each RLS decreases with decreasing RLS while the corresponding particle surface is, in general, getting rougher; (2) artificial neural network (ANN)-based mean impact values (MIVs) of Rinc at different RLS are calculated and the results prove the effective elimination of inter-scale effects by using Rinc; (3) Rinc shows a positive correlation with the rate of increase of surface area RSA at all RLS; (4) Rinc can be utilized to quantify the irregularity and roughness; (5) the surface morphology of a given particle shows different morphology variation in different sections, as well as different variation trends at different RLS. With the capability of eliminating the existing limitations of traditional morphology descriptors, the novel multi-scale descriptor proposed in this paper is very suitable for acting as a morphological gene to represent the multi-scale feature of particle morphology.

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