1st Try at FT-IR Spectroscopy

I’ll explain the idea of these new experiments in more detail later, but I had this data from today and wanted to get the information in my notebook. There is an Ft-IR spectrometer at CHTM (actually 2) and we were granted permission to use it by Dr. Sanjay Krishna courtesy of Stephen Myers and my buddy John Montoya.

The purpose is to figure out a way to accurately measure the amounts of D2O in H2O or H2O in D2O. Today was just about seeing whether we could conduct these experiments with the equipment we have (plastic macro cuvettes). The answer is no, but the experiments are still worthwhile.

We ran 3 experiments: (1) nothing in the sample chamber but air, (2) an empty cuvette in the beam path, and (3) a cuvette with pure H2O (deuterium depleted water). The spectrometer has the capability of subtracting (dividing) out the background, sort of like blanking a solution when dealing with a nanodrop. So we used the empty chamber and the empty cuvette experiments as background readings to test the H2O. Here is the data:

The following graphs are % Transmittance (y) vs Wavenumber (x).

 This is the empty chamber sample.

This is the blank cuvette experiment.

This is the same experiment, except that in this graph the air background reading has been divided out.

This is the DDW sample with the cuvette reading divided out.

The data isn’t reliable because you can see in the last data set that there are transmittance numbers above 100%. Right now I can’t explain the how’s and why’s because I don’t know all that much about the equipment or the process, but in this range we were getting rather low transmittance anyway so I wouldn’t expect to get accurate results.