Our latest video helps to explain why we use a diamond compression cell for IR microscopy.
Firstly, and most obviously, the optical pathlength through the sample is reduced by squeezing it between two windows, just like in a regular transmission cell. A flatter sample also reduces scattered light and increases throughput. But we also have to take a step back and examine the workings of the microscope.
The total energy through an infrared microscope is limited by the size of the aperture, while signal-to-noise depends on how much of the aperture is masked by the sample. So to get best results we need to flatten and spread the sample out, to fill more of the aperture and avoid reducing it further than we have to.
Microplastics and textile fibres are a perfect example of relatively compressible materials that benefit from using a diamond compression cell.
Should I use the cell assembled or disassembled?
After compression, many samples will strongly adhere to one window or the other. We can separate the two windows in this case and analyse the sample through only one window. This automatically gives us a throughput benefit, as well as avoiding any fringing patterns that occur due to the relatively high-refractive index of diamond windows.
If the sample does not adhere strongly to one window or springs back to its original size when the load is removed, it will have to be analysed between the two windows of the assembled cell.
Learn more about the Diamond Compression Cell HERE
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