We're doing photocatalysis with the catalyst fixed to a 2" Si wafer, washing an aqueous solution (methylene blue, the concentration varies but in the picture I believe it's 0.1 mMol/l) over the top in beakers that look like this

enter image description here

(the lid is the heatsink for the 365 nm UV LED that drives the reaction; that part is pretty much optimised).

The few we have are custom made, and we need some more. I can't find a source of anything comparable, but I'm only a physicist who doesn't necessarily know what's available or what terms to search for.

It needs two hose barbs as near the bottom as possible, and a flat base wide enough to lift a 2" wafer out (i.e. about a 60 mm minimum internal diameter).

They're also visible in this timelapse video of the reaction.

If such a thing exists, what's it called? Or is there something we could repurpose? Both the cost and the lead time of custom glassware are a bit high.

  • $\begingroup$ Does the vessel have to be glass? You could modify a plastic beaker of the right size with bulkhead unions and some O-rings/grommets. $\endgroup$
    – J. Ari
    Jan 30, 2018 at 22:19
  • $\begingroup$ @J.Ari I wondered about that. But I might have to go through the base because of the curvature, which is greater than the thickness of the o rings in my bulkhead fittings over the width of the fitting $\endgroup$
    – Chris H
    Jan 31, 2018 at 6:51

2 Answers 2


A beaker / reactor of such type would be rather expensive as well. If design and elegance do not matter you can easily adapt every suitably sized beaker by holding two pipes at the levels at which the hose barbs are supposed to be. Perhaps you choose a beaker a bit wider so there will be no turbulence or differences of sort as compared to what you are using.

Any flask or other container, combined with two small tubes and a couple of stands will effectively let you save money and time. Perhaps you must get space for the inlet and outlet through the led holder lid.

  • $\begingroup$ I wrote a rather detailed comment but it hasn't appeared, neither has my upvote. In summary: I assume you mean run the hoses from the top. A wider beaker would be needed to avoid shadowing the wafer, which would increase the system volume or decrease depth, but might be workable. Turbulence is good for mixing. Priming the pump (not shown) would be tricky. Modifying the metal lid is much easier the modifying the glass. I'm not sure about this approach but it's worth a shot. $\endgroup$
    – Chris H
    Jan 30, 2018 at 21:40
  • $\begingroup$ I think it must work with limited adjustment. Really. I mentioned a wider container so you can have space to go in with the in/out pipes even without touching the lid (avoid drill holing it ). I assume you can work in system open to air. Glad it may help $\endgroup$
    – Alchimista
    Jan 30, 2018 at 21:53
  • $\begingroup$ A non-vented system would be another experiment, and we'd machine a reaction vessel out of metal for that. Drilling holes in the lid changes less than a bigger beaker, plus that way I can mock something up tomorrow using one of these beakers with the hoses clamped off - I can make some assumptions about the light pattern to account for shadowing. $\endgroup$
    – Chris H
    Jan 30, 2018 at 22:01

I don't think these are UV LED. Most likely vanilla blue LED. You can buy strips of blue LED light and wrap it around a 500 mL beaker. Run your reaction in a second vessel inside that larger beaker. or else, you can use a aluminium sheet, cut vertical perforations and wrap the LED strips around it. Place the photocage around your reaction vessel.

  • $\begingroup$ I bought the LEDs. They're 365 nm. But the beaker is full of about 1 mMol methylene blue solution. $\endgroup$
    – Chris H
    Jan 30, 2018 at 21:36

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