for pure liquid samples

What is a thin film cell?
 a thin film cell
 is a drop of pure liquid sample
 sandwiched between salt (NaCl) discs

Thin film IR cells

Salt (NaCl) discs are used

To hold the sample

So the holder won’t absorb infrared light
 and only sample absorption is detected

Sample preparation
 so only dry (anhydrous) samples are used
 because even traces of water etch the IR discs
 affecting the path length of light
 and the optical quality of discs

use clean gloves to work with salt discs
 put on an extra pair of gloves
 to protect cells
 from anything aqueous on your regular gloves

Preparing salt discs

Slide off

The top of the

Desiccator

Remove

Salt discs

 replace
 desiccator cover
 immediately
 remove discs
 from sleeves and
 rest on kim wipe

to clean discs


 add a few drops of chloroform to each disc



 rub gently to clean off all traces of sample
…

adding sample








 add one or two drops of sample in the middle of the 1 st disc lower the 2 nd disc on top as shown to spread sample evenly

placing discs in cell holder
 use your finger
 to make a platform
 in the cell holder
 lower in
 the NaCl discs

do not wedge them

 gently
 place lid
 on top
 slide into position
 in light beam

 close
 sample
 compartment
 remove gloves
 before using
 keyboard

to clean discs


 add a few drops of chloroform to each disc



 rub gently to clean off all traces of sample
…

Keep discs dry



 replace in desiccator after cleaning
…