Recently in SEM applications Category

DIY scanning electron microscope

OK, here's a project for all the do-it-yourselfers out there. Build your own SEM! This guy did it and does a really good job of explaining how an SEM actually works.

I guess first hand knowledge on how one is put together really helps to understand the fundamentals of how all the pieces work together to make a microscope.

Makes me wish I had more time and a better supplied garage.

Very Small (and temporary) Holiday Greeting

Some folks at the University of Leeds, with a ton of holiday cheer, (and perhaps not enough work to do) have created a video showing how they put a Merry Christmas greeting onto a snowflake. The fine folks at Wired Magazine have the details.

Sedimentologists use many properties of individual sediment particles to help determine the environment that the sediments were deposited from. By examining the micro-scale surface morphology of particles of quartz it is possible to infer if that grain was deposited in an aeolian (wind), glacial (ice), or fluvial (river) environment as a couple of examples. Quartz is most commo9nly used because it is both abundant (most abundant mineral in the earth's crust) and resistant to weathering (so it retains microfeatures and is preserved in sedimentary rocks). This is extermely useful information to a sedimentologist.

But what do you do when you are trying to study environments with very few quartz grains? Well, a group from Massey University have done preliminary work to show that magnetite may be an adequate substitute for quartz. They observed features on magentite particles from glacial moraine deposits that are very similar to features on quartz particles from the same environments. While there are some inconsistencies between quartz and magnetite, it is a good preliminary study showing the potential to use another mineral to do this kind of analysis.

SEM/EDS-Analysis in Art History

A quick read on a case study on the use of SEM and EDS analysis of historical paintings was recently put up by Imaging & Microscopy. The analysis of paint pigments by light microscopy is a powerful application in the field of art history and conservation. Bay adding SEM and EDS analysis it is possible to add even more information about the use of various pigments and help understand the painting styles of significant artists. Also, from a historical perspective it is useful to track the trade in certain materials across cultures and geographies. But, perhaps most importantly, it is possible to detect fraudulent or counterfeit art before it goes to auction and ends up on display as an original work.

Moth wings by SEM

Interesting paper just put out in Microscopy Research and Technique. I'm no entomologist, but I do know that certain species of insects look different when imaged using non-visible wavelengths of light (UV or IR). This paper shows how the silk moth species Antheraea assamensis actually does it. The moths were imaged using UV photography, then the wing scales were imaged using SEM. Based on the SEM observation of the scale morphology the authors explained the optical properties and showed how the mating behavior changed under different lighting conditions.

Micropaleontoloty application

Came across this blog post this afternoon. An application of SEM to a field I am not terribly familar with. Using forams for dating is an interesting concept that I know next to noting about and is yet another application of SEM to geoscience.

An excerpt from the post:

Forams are microscopic plankton, and they leave a calcium carbonate shell behind when they die. When people go out on the IODP legs, one thing they use Foraminfera for is to date the layers of sediment that they are drilling. To make their identifications we need good reference pictures to see what the minute details of these shells are, what they texture of their shell wall is, etc.

SEM proves its worth in mining

News release from Constantine Metal Resources speaks about MLA (mineral liberation analysis) done with an SEM that provided detailed mineralogical identification, grain size, copper, zinc and lead distribution within mineral phases and the proportion of locked and liberated grains of ore minerals.

This kind of analysis is extremely useful in exploration geology. It allows a company to add information to the usual bulk assay analysis they are likely doing in parallel. It is critical to know what minerals the metals to be extracted are present in. But it is also critical to know how big the mineral grains are and how they are mixed with other minerals in the ore rock. These last two pieces of information dictate how the ore rock is processed (or if it is practical to process it at all) to extract the metals.

The MLA information coupled with bulk assay data have a major impact on determining whether or not an ore body is economical to mine.

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