Question

Hi everybody,

I need help! I've got a negative absorbance in my IR spectrum. Anyone knows the reason behind such results?

Answer 1

lots of things might account for this. The instrument might not have been fully warmed up, so the intensity is (slowly) but constantly increasing as you run samples. The solution might be so dilute that it's past the useful range of the machine. Contamination of some kind might also do it. It wouldn't be fingerprints or smudges on the glass, that would give absorbances that are too high, not too low.