One technique to prepare a sample for IR spectroscopy is to make a nujol mull.
A small amount of your compound is ground to a very fine powder using a mortar and pestle.
A few drops of nujol are then added,
and the two are mixed together to create a paste.
The sample is then transferred to potassium bromide discs.
These are very moisture sensitive so are stored with a drying agent.
[They have] to be handled with great care to make sure they don't come into contact with moisture or water,
otherwise the discs would dissolve.
The samples transfer to one of the discs using the flexible end of a small spatula.
Again care is taken with a spatula,
to ensure that you don't scratch the surface of the discs.
The two discs are then pressed together to create a film.
To support the discs in the spectrometer, plate holders are used.
They all have slightly different designs.
This one consists two separate plates held together by three screws.
The screws are tightened one-by-one,
to ensure the pressure is applied evenly across the plates.
This sample is now ready to go into the spectrometer.
You may come across other types of plate holder.
This is a different design, this one consists of a spring inside a central cylinder,
but they all have the same principle of simply holding the sample tightly in place,
ready for when it goes into the IR spectrometer.
Another way to prepare your sample for use in an IR spectrometer,
is to make a solution.
A small amount of your compound is added to a sample vial,
and solvent is then added to prepare a solution of approximately five percent concentration.
At undergraduate level, you'll generally be told which solvent to use.
The solution cell is used to contain the sample in the spectrometer.
Again this is stored in a dry environment.
The solution cell consists of two potassium bromide plates clamped together.
Any contact with moisture would damage the plates.
Having first carried out a spectrum of your solvent,
you can then transfer your solution to the cells.
Solution is added until all the air is expelled from the solution cell.
Small plastic plugs are then used to make sure none of your solution escapes.
You can see that all plate holders have a groove on either side
to ensure they fit snugly into the spectrometer.
They then fit directly into the path of the infrared radiation
to enable the spectrum to be recorded.