What I want to do
The square glass bottles we've used for fluorescence spectroscopy are sold out, and the nail polish bottles we've used are hard to get small enough and with flat sides. @mathew and I have been brainstorming some other options.
The literature review I've been doing mentions that it's best to let the laser pass through as little liquid as possible since the liquid can filter out the laser somewhat, and more importantly, the liquid can filter out the fluorescence emitted by the sample, like in this post by @eustatic:
Nanodrop and ultra micro cuvettes
@gaudi and @dusjagr's nanodrop research note, DIY Nanodrop and patent research by @mathew show a lot of options related to suspending a droplet somehow, either between two sheets of clear glass or plastic, or in some kind of hole:
One thing I worry about is making a mess -- it's great if we can completely seal the sample so it doesn't get toxic sludge all over the spectrometer, or your hands, and so that samples can be stored and transported.
"Ultra micro cuvettes" narrow at the bottom for a 1mm beam path (the thickness of the sample), but until I found this type with a round top, we were worried about leakage -- square-topped cuvettes have to be kept upright or they leak.
These have round caps, are plastic, UV-friendly, and $84 per hundred pack, $372 per 500: http://www.spectrecology.com/Disposable_Cuvettes.html or here on Amazon: http://www.amazon.com/BrandTech-759230-UV-Transparent-Disposable-Ultra-Micro/dp/B003ULPARY
These have a "chemical compatibility chart" here: http://www.brandtech.com/cuvette_comp.asp
It'd be too bad to use a specialty material, but we're already getting really particular about the jars, so they're not universally available either.
But Mathew and I talked today and we came up with the idea of something like a rigid Otter Pop, which could be made from plastic thermally sealed over a butter knife, more or less.
We could make them by sealing a roll of plastic (like a candy shop) every 1cm or so and cut it in half lengthwise, so they're open at one end. It'd be nice if we could use something rigid so they could slot in like a projector slide, and we could edge-light them with a laser. This needs to be tried out! @Mathew has a sandwich bag sealer :-)
So we have a lot of things to try out, now!