Other
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p43a1652t&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P43A-1652
Other
[6015] Planetary Sciences: Comets And Small Bodies / Dust
Scientific paper
Many important measurements applying concentration determinations for small particles (e.g., determining cosmogenic exposure ages of presolar grains [1]) depend on the mass of a given particle. Masses of small μm-sized samples such as extraterrestrial dust returned by space missions are often not well constrained due to measurement limitations, and can be often only estimated. Although many of these particles have a known average density, their volume is hardly ever known with enough precision. Our project objective is therefore to develop a nondestructive method for quantitative volume determination of small dust particles. We start with volume analyses of small standard shapes using scanning electron microscope (SEM) images taken under different tilting angles. Aluminum and titanium spheres with three different diameters (0.794, 2.38, and 3.18 mm) were weighted on a micro-balance. Their volumes were determined using the dimensions given by the manufacturer, as well as by using the weights and the respective densities of the materials. The spheres were then imaged in an SEM under different tilting angles ranging from -50 to +50 degrees. Images were subsequently analyzed using the software MeX (Alicona, http://www.alicona.com), which was successfully used for comet dust impact craters [2]. The volumes determined using the diameters given by the manufacturer and by weighing the samples are consistent within uncertainties. With the software MeX we were able to reconstruct 3D objects that resembled hemispheres. This is expected because by looking at the sample under a total angle difference of 14 degrees, about 54% of the sphere is visible to the software. To improve the rendering process we masked the imaged sphere with a black background using ImageJ (http://rsbweb.nih.gov/ij/). Since the 3D model only showed the upper half of the sample, we assumed symmetry with the lower part that was not visible and multiplied the volume returned from MeX by a factor of two. Such an assumption is valid for spheres but will add uncertainty when analyzing asymmetric samples. The software-determined volumes fit well with the volumes determined as described above. We found volume differences of 17% for the big sphere, 27% for the medium sphere, and 32% for the small sphere. All volumes are too small which indicates that the 3D model contained less than half the sample. The smooth surfaces of spheres posed a problem for the software as there are no unique surface reference points in order to properly render the 3D model. We therefore expect to get better results for objects with more surface structure and edges. As a next step we mounted and imaged several euhedral mineral grains and will present results at the meeting. We are currently evaluating other software packages that allow the use of images at higher tilting angles, to increase the part of the sample that can be seen. We would like to thank Ben Myers, Northwestern University, for the opportunity to use the MeX software package and for his support.
Davis Aileen M.
Heck Ph. R.
Trappitsch R.
No associations
LandOfFree
Volume Measurement of Small Particles Using SEM Images does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Volume Measurement of Small Particles Using SEM Images, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Volume Measurement of Small Particles Using SEM Images will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-871897