Well, that's the kind of ampoule you'll need a deft touch with. The glass is thin and it will sag and constrict in an instant if you use too hot a
flame with a full -1 bar vacuum (or anything close) applied to it. When I seal those types of ampoules, a "vacuum" of 50 mm Hg is way more than
enough. In fact, a small rubber pipette bulb pulls plenty of vacuum to give a good seal. If you've never done it before, I'm sure you'll practice
first. If you can, it is highly desirable to melt the seal into a well-fused somewhat rounded end w/o a sharp point. On another front, your product
quality will likely depend more on your reductant than on the CsCl, which is usually 99 - 99.9 % pure, metals basis. The typical Li sample may contain
a per cent of Na or more. This will co-distill with the Cs. Ca is easier to get as a pure metal, but to get a good yield you need small clean filings
to achieve homogeneity in your charge as the reaction mixture is not very fluid at all. At least you don't need too much. Do this: Ca is available as
chunks on eBay. Get some, clean it with a wire wheel or brush, clamp it in a cleaned-off vice and file it while catching the filings in whatever you
have around. Do this right before before use. Not the day before, but immediately before. You could use high purity Li to best effect though. This
has become (easily) commercially available to the public in the last year. These are not new facts but they are vitally important. If you pay
attention to the little things you'll get Cs that is always solid at RT. |