Hi,
We often use transmission gas cells with continuous gas flow for measurements in the soft X-ray range, and we are wondering if these cells are also a good option for measuring air/moisture-sensitive samples in the hard X-ray range.
Two ~150 nm SiN windows isolate the sample and the gas from the environment, and we have never had problems with X-ray-induced window damage or leaks. Even with continuous helium flow, the pressure in the chamber was <1E-6 mbar.
A single window is sufficient for emission experiments and the design can be adapted to allow for large take-off angles.
Does somebody already have experience using cells with SiN/SiC membranes in the hard X-ray range and know what the challenges or limitations are?
Best
Richard
On 24/03/2025 20:35, Matt Newville via Ifeffit wrote:
Hi Helen,
+1 on using Aluminized Mylar and Aluminized Kapton (and we have some of
each at sector 13 if you want to borrow some).
The aluminum layer on Mylar is very thin (you can see visible light
through) but it holds helium. In an undulator beam, Mylar might last 10
seconds. The thin aluminum layer helps a lot, but I would not guarantee
this by itself for multiple hours.
Kapton is leaky but holds up better in an undulator beam (but you can burn
a micro-hole in it over several hours with 10^13 photons/sec in a few
square microns: loving APS-U!) The Aluminized version is a non-trivial
thickness (several microns) of aluminum, so not suitable for tender beams,
but should be OK above 5 keV (wait, which "V" in VTC -- Yb K or L3 edge?).
I'll say that we have had decent luck (with old APS undulator) with samples
in an otherwise regular Ziplock bag with a Kapton film window (held on with
carefully cut packing tape) for X-rays in and out and over-pressuring the
bag with blow-off N2 (which is free) or helium (which is not). But,
oxygen-sensitivity can vary a lot, so I’m not sure there is a single “best”
solution.
--Matt
On Sat, Mar 22, 2025 at 3:06 PM matthew marcus via Ifeffit <
ifeffit@millenia.cars.aps.anl.govmailto:ifeffit@millenia.cars.aps.anl.gov> wrote:
Aluminized mylar has a much lower permeability to oxygen than polyethylene
and still works with a heat-sealer. I'm assuming you're in the hard- or
tender X-ray range. mam On 3/22/2025 12: 16 PM, Carlo Segre via Ifeffit
wrote: > Hi Helen, We
ZjQcmQRYFpfptBannerStart
This Message Is From an External Sender
This message came from outside your organization.
ZjQcmQRYFpfptBannerEnd
Aluminized mylar has a much lower permeability to oxygen than
polyethylene and still works with a heat-sealer. I'm assuming you're in
the hard- or tender X-ray range.
mam
On 3/22/2025 12:16 PM, Carlo Segre via Ifeffit wrote:
Hi Helen, We have had luck using a vacuum sealing system such as used
for food. However the Polyethylene is subject to degradation under the
beam so that wrapping with Kapton is helpful as well as double bagging
it. Finally, if you keep it under
ZjQcmQRYFpfptBannerStart
This Message Is From an External Sender
This message came from outside your organization.
ZjQcmQRYFpfptBannerEnd
Hi Helen,
We have had luck using a vacuum sealing system such as used for food.
However the Polyethylene is subject to degradation under the beam so
that wrapping with Kapton is helpful as well as double bagging it.
Finally, if you keep it under Argon when transporting it to the beamline
and then in a helium filled chamber, you should avoid the oxidation.
Carlo
--
Carlo Segre, Duchossois Professor of Physics
Illinois Institute of Technology
------------------------------------------------------------------------
*From:* Helen Chen via Ifeffit