Sigh. The problem with your request is that you have to go all the way back to the 1930s to find a time when anything about the infrared absorption spectrum of CO2 was remotely publishable. Here, for example: https://journals.aps.org/pr/abstract/10.1103/PhysRev.43.716
To answer some of your other concerns:
The temperature of the CO2 is effectively irrelevant to its ability to block infrared radiation (within limits, of course: too cold and it would freeze; too hot and it would flood the detector with its own glow). Within +/- 20 degrees of room temperature, though? Nah.
Pressure in the cylinder before and after? One atmosphere. Look closely at the end of the tube: the only thing covering it is a sheet of cling wrap. Polyethylene is one of the few solids that is (mostly) transparent to infrared, so this makes sense.
CO2 concentration before and after? Irrelevant. You asked for an experimental demonstration that CO2 absorbs infrared. I gave you that.
Your request to flood the tube with argon is also nonsensical. What information would that provide that isn’t provided by the existing control (the starting state of the tube, filled with ambient air)?
Scaling the CO2 concentration down to .04% would only make sense if you also scale the length of the tube up to the height of the atmosphere (or at least the height that the atmosphere would be if it were all at 1 atm pressure). If you want to scale the experiment down to see the effect in a lab setting, you need to scale the CO2 concentration up to match.
