Question

Help please <3 Air molecules can also absorb IR radiation. So, when we analyze any sample with IR light that light must travel through both air and our sample for the analysis. How might you expect we could correct for this during our sample collection to obtain the spectrum of just our sample and not the sample + air? (Hint: it will require taking two IR readings).

Answer 1

To correct for the interference of air molecules in the IR spectrum, we can take two IR readings - one with the sample in place and the other with no sample but with air in the sample chamber. By taking the difference between the two readings, we can obtain the spectrum of the sample alone, without interference from the air. This technique is known as background subtraction. The first reading with the sample in place will be the test variable, while the second reading with air in the sample chamber will be the control variable. The outcome variable will be the resulting spectrum after subtracting the control from the test variable.