CO2 peaks in the middle, water lines on either side. I get that. But what about those lines in the CH-stretch region? They are obviously very normal for an FT-IR background- everyone sees them, they're all over the internet. But WHAT ARE THEY???? No one knows- not even the IR spectroscopy veterans I've talked to. They're some kind of hydrocarbon, I guess, and they're not a gas because they are unaffected by purging. This is a spectrometer looking at no sample, with no windows, nothing, and fwiw this is using an MCT/A detector. I feel like I should know this, but maybe I'm not using the right resources?
Thanks for any help!