WDS window material and thickness

[SteveSeddio]

Does anyone happen to know what the material and thickness is of the windows between the WDS and chamber on Cameca probes?

Thanks!
-Steve

[Probeman]

Does anyone happen to know what the material and thickness is of the windows between the WDS and chamber on Cameca probes?

Thanks!
-Steve

Hi Steve,
Here are the Moxtec specs which we usually buy direct from them now.  That's where Cameca gets them!

LWN00015 Column Separation Windows have 1500A polymer film with no coating (we offer 3000A, 6000A, and 12000A Polymer film). However, we can do coating if needed (Standard Al coating thickness is 100A). Price is $250. Send us the column separation windows (for example, stainless steel holders with PTFE sealing washers) that you need repaired and we will replace the film that is on the plastic ring. This is a standard service that we offer for column separator windows.

I'm sure it is a polypropylene film. If it is, the formula is (C3H6)n, and if it's 0.15 um thick and assuming 1.0 density, here are some calculations for x-ray transmission (using CalcZAF):

F Ka, X-ray transmission fraction of thickness  .15 um (average u/p =  5475.972) =  .9211434
O Ka, X-ray transmission fraction of thickness  .15 um (average u/p =  10617.65) =  .8527705
N Ka, X-ray transmission fraction of thickness  .15 um (average u/p =  21847.58) =  .7205693
C Ka, X-ray transmission fraction of thickness  .15 um (average u/p =  2070.655) =  .9694176
B Ka, X-ray transmission fraction of thickness  .15 um (average u/p =  5674.668) =  .9184021
Be ka, X-ray transmission fraction of thickness  .15 um (average u/p =  18116.66) =  .7620448

Nitrogen Ka is of course heavily absorbed by carbon.

[SteveSeddio]

Thanks, Probeman!

I guessed polypropylene with a 0.2 um thickness... so close!

[BenjaminWade]

Just on windows but slightly off topic, a little while back we had a talk from EDAX about some EDS detectors and they focussed on their Si3N4 windows and how much better they were for mechanical robustness and better light element x-ray sensitivity (35% better for O), despite the windows being less than 100nm thick. Can anyone tell me why this material isn't used for the separation windows in electron microprobe, especially in FE-EPMA at low voltage? Am I missing something crucial here?

Here are a couple of links:
http://www.edax.com/products/eds/detectors/octane-elite-sdd-series.aspx
http://www.edax.com/videos/material-properties-of-silicon-nitride-windows.aspx