In a sequence of recent posts on DLR I have decoded the spectrum understanding that it is a fabricated "product" of the team behind AERI from temperature measurements by the interferometer: The sensitive interferometer thermometer measures the temperature of a tiny fraction of CO2 around wave number 667 and the AERI team then fabricates a major warming effect of the atmosphere from the presence of CO2 as the red part of the curve associated with CO2.
Seeking a history of AERI leads back to the project SPECTRE Experiment shaped by ICRCCM sponsored by the US Department of Energy DOE and and the World Meteorological Organization, with ICRCCM having a "role as lead agency for investigating the CO2-climate problem". The starting point of SPECTRE was identification by ICRCCM (1988) that measurements of DLR could vary with 30-70 W/m2 out of a total of 200 - 400 W/m2, while the estimated impact of CO2 could be at most 4 W/m2.
To prove that the "CO2-climate problem" was a real problem, better instruments were obviously needed, and so the SPECTRE Experiment got started and eventually produced radiance spectra like that above with a major role given to CO2. As with AERI the SPECTRE team measured temperatures but fabricated spectra, according to the wish of the contractor: Undeniable instrumental evidence of the reality of the "CO2-climate problem", marked in red to emphasize the alarm.