Deploying the membranes
In addition to the transparency in a highly interesting and previously inaccessible energy region, the JAVU carbon membranes also offer surprisingly good mechanical integrity, chemical stability and UHV-compatibility. Nonetheless, there are some good practices that are recommended when dealing with the membranes.
Do consider the following
Don’t poke the membrane! Even the fiber from a very soft tissue will immediately break the membrane.
The ‘thickness’ of the membranes is of the order 100nm, about 1/1000 of a human hair. That means any fiber you can see, no matter how soft, is very likely to poke through the membrane and ruin it. Be very careful not to lay the frame with the membrane the wrong side down on any surface, definitely do not poke the membrane with tweezers and do not blow dust off the surface of the membrane without extreme caution.
The frame holding the membrane is made from silicon which is a very brittle and quite stiff material. Many frames have broken from mounting the frame the wrong way – do not press the frame against bare metals, no matter how smoothly machined their surfaces are! The good way – and proven to be successful – to hold the membranes is to clamp them between two rubber O-rings.
Modern beamlines at high brightness synchrotrons with well-focused, high-flux beams have sometimes been a challenge. The mechanism is not known, but for example in pure oxygen at the SAXES beamline at the SLS, the life-time was once as short as 1 hour – on the other hand it has also been over 24 hours. At this point it is not known how to predict the life-time of the membranes. For a perspective, an experienced user of different membranes characterized the JAVU carbon membranes as ‘impressively durable!’.
Precautions
Despite the surprisingly durable nature of the membranes, they are bound to break sooner or later. Hence, the beam-line scientist and the synchrotron managers will demand a fail-safe system that quickly closes valves to the beam-line when a gas or liquid is released in the end-station. It is also prudent to limit the amount of sample that can leak by closing the supply in case of a leak. Less critical, but users should consider splash guards and other precautions if acids or other liquids are being used in the experiment. It can be difficult to clean a high vacuum chamber if it is contaminated with corrosive liquids.
Contact us about your intended experiment to see if there is some existing experience to help you out.