Author Topic: Spectral resolution and crystal size  (Read 6383 times)

wrigke

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Re: Spectral resolution and crystal size
« Reply #15 on: March 11, 2019, 03:18:29 pm »
My SX100R (shielded EPMA) was built around 2009.  I have the boxes in which the crystals shipped.  All of my crystals, layered and non-layered came from St Gobain, France.

I would like to have the opportunity to try new crystals with different geometries (e.g. Johann vs. Johannson) but would need to find a vendor who will make crystals on demand.  I think St. Gobain only sells through Cameca, not directly to the customer.

It would be nice to have some crystal manufacturers that could make high quality crystals on demand.

Karen Wright
« Last Edit: March 13, 2019, 07:41:41 am by wrigke »

Probeman

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Re: Spectral resolution and crystal size
« Reply #16 on: March 11, 2019, 04:57:18 pm »
My SX100R (shielded EPMA) was built around 2009.  I have the boxes in which the crystals shipped.  All of my crystals, layered and non-layered came from St Gobain, France.

Incidentally, one of my colleagues attempted to have St Gobain make a custom crystal for their EPMA.  St Gobain was very reluctant to do so, and when they finally did it, it was very poorly done and ultimately unusable.

It would be nice to have some crystal manufacturers that could make high quality crystals on demand.

Karen Wright

Hi Karen,
Do you have any other details?  Was it a normal crystal or a multi-layer?

Are you asking if there are other sources for Bragg crystals?  Where does JEOL get their WDS crystals?  Also Thermo uses WDS crystals, do anyone know where they get them from?

I only know of the soft x-ray optics group at LBL.  When I was there I worked with Jim Underwood to develop better LDE crystals for quantifying N ka.

http://www.cxro.lbl.gov/

Jim's researchgate link is:

https://www.researchgate.net/scientific-contributions/2091855472_James_H_Underwood
john
« Last Edit: March 11, 2019, 10:07:47 pm by Probeman »
The only stupid question is the one not asked!

Philipp Poeml

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Re: Spectral resolution and crystal size
« Reply #17 on: March 13, 2019, 01:50:14 am »
Did you take into account that most likely most large crystals are Johansson and most "normal" crystals are Johann?

To me it seems much more difficult to align a Johansson crystal, because it is fully focussing, than a Johann crystal.

Anyway I wanted to ask about your alignment procedures, but maybe in another thread. There is something I do not yet fully understand. Because there are multi parameters you can adjust while aligning a crystal: Peak position and the position on the Rowland circle.


Probeman

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Re: Spectral resolution and crystal size
« Reply #18 on: March 13, 2019, 09:26:35 am »
Did you take into account that most likely most large crystals are Johansson and most "normal" crystals are Johann?

To me it seems much more difficult to align a Johansson crystal, because it is fully focussing, than a Johann crystal.

Anyway I wanted to ask about your alignment procedures, but maybe in another thread. There is something I do not yet fully understand. Because there are multi parameters you can adjust while aligning a crystal: Peak position and the position on the Rowland circle.

I have notes on adjusting the Bragg crystals on Cameca spectrometers, but I have not done the procedure myself. However our instrument engineer recently devised a holder for a laser pointer that mounts in the spectrometer column separation window "tunnel", and used this light beam to align a PET crystal that he had moved from our old SX50 to our SX100 as described here:

https://probesoftware.com/smf/index.php?topic=18.msg6949#msg6949

There is also a topic on Bragg crystals here:

https://probesoftware.com/smf/index.php?topic=575.0
« Last Edit: March 13, 2019, 10:09:24 am by Probeman »
The only stupid question is the one not asked!

Philipp Poeml

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Re: Spectral resolution and crystal size
« Reply #19 on: March 13, 2019, 10:16:30 am »
I have notes on adjusting the Bragg crystals on Cameca spectrometers, but I have not done the procedure myself.

Are those notes available? I would be interested to learn more about that!

Probeman

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Re: Spectral resolution and crystal size
« Reply #20 on: March 13, 2019, 10:22:06 am »
I have notes on adjusting the Bragg crystals on Cameca spectrometers, but I have not done the procedure myself.

Are those notes available? I would be interested to learn more about that!

Next week when I'm back in the lab I will scan my old notes in the SX100 notebook.
The only stupid question is the one not asked!