Infrared transmittance spectra of haze samples from the six experiments. (a) Transmittance spectra (3600–1000 cm⁻¹) of haze particles formed with CH₄ as the carbon source. (b) Transmittance spectra (3600–1000 cm⁻¹) of haze particles formed with CO as the carbon source. The blue, green, and red lines represent the H₂O-rich, N₂-rich, and CO₂-rich conditions, respectively. The spectra are vertically offset and rescaled for clarity, with all peaks within each spectrum multiplied by the same constant factor so that relative peak intensities and peak positions are preserved.