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Re: SEM Gloat
Posted: Tue Dec 02, 2014 11:57 pm
by Jerry
If you have samples just send them to me.
Done a bunch of work. I found out that the EDX controller I have also has digital capture capabilities. I found the external Digital Beam Control box on ebay for $110 shipped and ordered a couple fiber optic cables to connect it to it's mainframe. I got it all hooked up today and it works well. This is the first digital capture out of the scope, 30x image of a 1/8" dia screw head on a sample holder and the edge of a dime:
SCREW by
macona, on Flickr
Re: SEM Gloat
Posted: Wed Dec 03, 2014 1:35 pm
by Doug Coulter
Awesome! And, I bet it even looked pretty clean to the naked eye. Amazing how the right tool shows you what it really is like. I know I spill one cat hair into a vacuum and my mass spec can see it for a long time, even though I can't. One fingerprint stays for a week or so...even with some baking. Suddenly there's all these high-mass lines from complex hydrocarbons.
Re: SEM Gloat
Posted: Thu Dec 25, 2014 1:40 am
by Jerry
Got the EDX running, EDX allows you to do elemental analysis by sampling the x-rays that are created when the electron beam hits the target in the microscope.
I picked up a 50L dewar of liquid nitrogen Monday and filled the dewar on the EDX head. You need to let it sit from 4-10 hours to make sure the sensor is cooled. If the sensor is not cool (cryogenic temps) the sensor will be ruined.
I threw a dime in the chamber and scanned it and did an acquisition with the software and it showed me some peaks, a dime's outer plating is about 75% copper and 25% nickel. The histogram showed some peaks pretty close to where they should be, it needs to be calibrated and the gains adjusted but it is pretty good for just hooking it up. I need to go through the manual some more and do all the adjustments.
I also picked up another sensor head off ebay the other day. It has different windows you can use as well as a windowless operation mode that will allow you to sample light elements like carbon and oxygen. The standard sensor used a beryllium window which makes it hard to see light elements.
dimeedx by
macona, on Flickr
Re: SEM Gloat
Posted: Thu Dec 25, 2014 5:28 pm
by Doug Coulter
That's VERY nice. I suppose you could check precious metals for adulteration too - but if that gets known you'll be swamped with requests
Re: SEM Gloat
Posted: Fri Dec 26, 2014 2:49 am
by Jerry
I calibrated the EDX tonight, the software uses a sample with aluminum and copper to create a spectrum and then figures out the offset and gain to get the peaks in the right place. With that done I zoomed into the little screw in the picture with the dime edge and did an acquisition. This is what I got and the analysis side says the screw is composed of the following:
Code: Select all
Element Line Weight% K-Ratio Cnts/s Atomic%
---------------------------------------------------------
Al Ka 6.26 0.0115 90.84 13.78
Fe Ka 1.68 0.0206 77.55 1.79
Ni Ka 1.06 0.0130 39.00 1.08
Cu Ka 55.95 0.5566 1483.97 52.35
Zn Ka 31.62 0.3132 728.50 28.76
Sr La 1.91 0.0066 19.13 1.30
Mo La 1.51 0.0079 23.45 0.94
Total 99.99
This works out to be a brass with aluminum added. Adding aluminum increases the strength of brass and makes it more corrosion resistant.
screwspectrum by
macona, on Flickr
Re: SEM Gloat
Posted: Sun Dec 28, 2014 3:49 am
by Jerry
I threw a piece if U Ore in the scope to see what it would show, here it is:
Code: Select all
[A N A L Y S I S R E P O R T]
GENERAL CONDITIONS
------------------
Result File : UORE
File Version : 1
Background Method : Foil
Decon Method : Gaussian
Decon ChiSquared : 6.13
Analysis Date : 28-DEC-2014
Microscope : SEM
Comments :
ANALYSIS CONDITIONS
-------------------
Quant. Method : XPP/ASAP
Acquire Time : 400 secs
Normalization Factor: 100.00
SAMPLE CONDITIONS
-----------------
kV : 30.0
Beam Current : 100.0 picoAmps
Working Distance : 25.0 mm
Tilt Angle : 30.0 Degrees
TakeOff Angle : 35.0 Degrees
Solid Angle*BeamCurrent: 0.9
Element Line Weight% K-Ratio Cnts/s Atomic%
---------------------------------------------------------
Mg Ka 3.16 0.0117 9.87 5.37
Al Ka 8.21 0.0365 33.43 12.59
Si Ka 40.97 0.2064 194.23 60.36
Ca Ka 7.39 0.0471 33.73 7.63
Ti Ka 0.00 0.0000 0.00 0.00
Fe Ka 8.69 0.0743 32.49 6.44
Cu Ka 3.47 0.0309 9.58 2.26
Pd La 0.00 0.0000 0.00 0.00
Au La 12.69 0.1014 8.26 2.67
U La 15.42 0.1138 2.89 2.68
Total 100.00
I was surprised by the gold. I guess I should have not been, U was first found in Gold mines so says the internets. But I am scanning a very tiny piece of the ore so who knows if it is homogenous throughout the sample.
UOre by
macona, on Flickr
Re: SEM Gloat
Posted: Fri Jan 02, 2015 9:14 pm
by Jerry
Tried the Map mode of the EDX for the first time last night. In the center window you can see an image of the sample (U Ore) and the surrounding images are heat maps of different elements that are found in that image. the more towards the red end of the spectrum, the more of that element was found. This was a "quick" 256x256 scan at 15ms per pixel dwell time. It took 15 minutes. Looks like it is a very time consuming process but still pretty neat.
uoremap by
macona, on Flickr
I analyzed a piece of goldish metal that came out of a machine that was used for washing silicon wafers. It is 81% gold, 11% rubidium, 3% Iron, and the rest copper. I was not expecting to find this in the flake, this is at 490x.
GOLDFLAE by
macona, on Flickr
Re: SEM Gloat
Posted: Wed Jan 07, 2015 3:05 pm
by Doug Coulter
This is all just total, utter awesomeness! I want one, but also wish I had room for one. Darnit.