I want to make optical measurements (fluorescence) of a liquid sample (fluorophore dissolved in 2-methyltetrahydrofuran) inside of a cryostat. The problem is that when I make my sample (in a cuvette) and introduce it into the cryostat once I put it under vacuum the seal on the cuvette does not always withstand the high vacuum of the cryostat. As a result I will sometimes evaporate my solvent before I freeze it.
I would also like to make measurements above the freezing point of the solvent but at temperature that need me to keep the vacuum running this also leads to solvent evaporation. This changes the concentration of the sample possibly adding additional error to the measurement.
I am currently using a 1 or 2 mm pathlenght cuvette with a Teflon plug that I hole down with Teflon tape but this is not working that well.
Are there any special sample holders for this kind of measurement?
if yes, what are they and where can I get them?
If not, is there anybody with experience using cryostats that can offer me some advice on how to make my measurements?
HPLC equipment, which basically deals with an optical measurement has a well designed leak proof sample cell suitable for studying the abosrption coefficient of liquids. Maybe you can look at these designs and carefully modify them for cryo applications.
K. Sreenivas
Would something like the cuvette holder sold by Janis work for you? It has a spring that holds down the lid.
http://www.janis.com/Products/AccessoriesandAncillaryEquipment/CryogenicAccessories.aspx
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